Pathogenetic mechanisms in experimental immune fever.

When rabbits sensitized to human serum albumin (HSA) are challenged intravenously with specific antigen, fever develops and two transferable pyrogens can be demonstrated in the circulation. The first appears prior to the development of fever and has properties consistent with soluble antigen-antibody complexes. These have been shown to be pyrogenic when prepared in vitro and to produce a state of febrile tolerance when repeatedly administered. The second pyrogen, demonstrable during fever in donor rabbits, appears to be similar to endogenous pyrogen described in other experimental fevers. It is postulated that the formation of antigen-antibody complexes constitutes an important initial phase of the febrile reaction in this type of immune fever.

Hydrogen peroxide release from mouse peritoneal macrophages: dependence on sequential activation and triggering.

Using a specific and sensitive fluorometric assay, the H2O2 release from as few as 2 X 10(5) mouse peritoneal macrophages could be detected continuously and quantitated. It is emphasized that the assay measured H2O2 release, not production. Induction of H2O2 release required sequential application of two stimuli: the administration of an activating agent to the mice from 4 days to 10 wk before all harvest, and the exposure of the cells in vitro to a triggering agent. BCG was most effective as an activating agent, resulting in peritoneal macrophages which could be triggered to release H2O2 almost as copiously (8 nmol/10(6) macrophages per 5 min) as mouse peritoneal PMN (9 NMOL/10(6) PMN per 5 min). Casein and C. parvum could also serve as activators, but thioglycollate and FCS were ineffective after single injections. PMA was a potent triggering agent, resulting in a maximal rate of H2O2 release after a latency of about 40 s for cells in suspension. Other triggering agents included the ionophore A23187, concanavalin A in the presence of cytochalasin B, and phagocytosis. H2O2 release could be attributed to macrophages and PMN in peritoneal cell suspensions or in preparations of adherent peritoneal cells, but not to lymphocytes. Indirect evidence suggested that the H2O2 detected was formed from superoxide anion. These observations appear to justify renewed interest in the idea that H2O2 may be important in macrohpage antimicrobial and antitumor mechanisms.

Studies on the effect of experimental nonketotic diabetes mellitus on antibacterial defense. I. Demonstration of a defect in phagocytosis.

Chronically diabetic nonketotic rats were shown to be more susceptible to experimental Type 25 pneumococcal pneumonia than nondiabetic rats. The cumulative mortality in the diabetic group was significantly higher at infecting doses of 10(3), 10(4), 10(5), and 10(6) organisms, and the LD(50) was less than one twentieth of that for the nondiabetic group. More than ten times as many viable pneumococci were found in the pneumonic lesions of the diabetic animals at 24 and 36 hr as were present in the lesions of the nondiabetic controls, and serial histologic studies revealed that phagocytosis was strikingly depressed in the alveolar exudates of the diabetic animals. The diabetic state was also found to cause a similar depression of in vivo phagocytosis in preformed peritoneal exudates. The results of in vitro experiments indicated that the principal defect in the diabetic animals resided in their serum rather than in their polymorphonuclear leukocytes. The depressive factor in the serum was identified as the abnormally high concentration of glucose. Since equivalent molar concentrations of unmetabolized sugars added to normal serum caused a similar depression of phagocytosis, it was tentatively concluded that the action of the glucose on the leukocytes was primarily osmotic. The sensitivity of the granulocytes to the glucose effect, however, depended upon the conditions of the phagocytic test. Only when the pneumococci were encapsulated and the leukocytes derived from inflammatory exudates were crowded together, as in vivo, was the depressive action of the glucose clearly demonstrable.

Studies on the origin of human leukocytic pyrogen.

Release of the protein molecule, leukocytic pyrogen, is one of the many reactions exhibited by leukocytes after phagocytosis. After the ingestion of heat-killed S. albus, a 3-4 hr latent period exists, during which human peripheral leukocytes release no pyrogen, yet cellular metabolism is altered in such a way that pyrogen output may subsequently occur in the absence of further phagocytosis. Transcription of messenger RNA and translation of new protein are initial events in the. activation process, since addition of the inhibitors, actinomycin D, and cycloheximide or puromycin, during this period markedly depressed or abolished subsequent pyrogen release. These effects were noted to be dependent upon the time of addition of the inhibitors. None of the inhibitor drugs interfered with cell viability as measured by phagocytosis and hexose monophosphate shunt activity, nor did they alter the pyrogenicity of preformed leukocytic pyrogen. Vincristine did not inhibit pyrogen formation, consistent with its reported failure to alter RNA synthesis in mature human granulocytes. The glycolytic inhibitor, sodium fluoride, blocked pyrogen release both when added prior to particle ingestion or 1 hr after the initiation of phagocytosis. Whereas inhibition of phagocytosis would explain the sodium fluoride effect prior to 1 hr, this was not observed in leukocyte preparations incubated for 1 hr with S. albus before adding sodium fluoride. When sodium fluoride was added to preparations 2 hr after the start of incubation, the LP production was unimpaired. Potassium cyanide had no effect on cell activation or pyrogen release. These findings suggest that the primary energy supply for the activation process is derived from high energy phosphate bonds provided by anaerobic glycolysis. Since the major amount of cell activation appears to occur in the 1st hr after phagocytosis, this energy might be involved in the induction of a genome leading to the transcription of m-RNA and its translation into new protein or is required for polysome integrity during protein synthesis. It is suggested that this new protein may be leukocytic pyrogen itself, or an enzyme responsible for cleaving it from an inactive precursor.

Structural analysis of human neutrophil migration. Centriole, microtubule, and microfilament orientation and function during chemotaxis.

Orientation of nucleus, centriole, microtubules, and microfilaments within human neutrophils in a gradient of chemoattractant (5 percent Escherichia coli endotoxin-activated serum) was evaluated by electron microscopy. Purified neutropils (hypaque-Ficoll) were placed in the upper compartment of chemotactic chambers. Use of small pore (0.45 mum) micropore filters permitted pseudopod penetration, but impeded migration. Under conditions of chemotaxis with activated serum beneath the filter, the neutrophil population oriented at the filter surface with nuclei located away from the stimulus, centrioles and associated radial array of microtubules beneath the nuclei, and microfilament-rich pseudopods penetrating the filter pores. Reversal of the direction of the gradient of the stimulus (activated serum above cells) resulted in a reorientation of internal structure which preceded pseudopod formation toward the activated serum and migration off the filter. Coordinated orientation of the entire neutrophil population did not occur in buffer (random migration) or in a uniform concentration of activated serum (activated random migration). Conditions of activated random migration resulted in increased numbers of cells with locomotory morphology, i.e. cellular asymmetry with linear alignment of nucleus, centriole, microtubule array, and pseudopods. Thus, activated serum increased the number of neutrophils exhibiting locomotory morphology, and a gradient of activated serum induced the alignment of neutrophils such that this locomotory morphology was uniform in the observed neutrophil populayion. In related studies, cytochalasin B and colchicines were used to explore the role of microfilaments and microtubules in the neutrophil orientation and migration response to activated serum. Cytochalasin B (3.0 mug/ml) prevented migration and decreased the microfilaments seen, but allowed normal orientation of neutrophil structures. In an activated serum gradient, colchicines, but not lumicolchicine, decreased the orientation of nuclei and centrioles, and caused a decrease in centriole-associated microtubules in concentrations as low as 10(-8) to 10(-7) M. These colchicines effects were associated with the rounding of cells and impairment of pseudopod formation. The impaired pseudopod formation was characterized by an inability to form pseudopods in the absence of a solid substrate, a formation of narrow pseudopods within a substrate, and a defect in pseudopod orientation in an activated serum gradient. Functional studies of migration showed that colchicines, but not lumicolchicine, minimally decreased activated random migration and markedly inhibited directed migration, but had not effect on random migration. These studies show that, although functioning microfilaments are probably necessary for neutrophil migration, intact microtubules are essential for normal pseudopod formation and orientation, and maximal unidirectional migration during chemotaxis.

Myeloperoxidase-mediated iodination by granulocytes. Intracellular site of operation and some regulating factors.

The intracellular site of operation of the myeloperoxidase-H(2)O(2)-halide antibacterial system of granulocytes has been determined by utilizing measurements of the fixation of iodide to trichloracetic acid (TCA) precipitates of subcellular fractions, including intact phagocytic vesicles. Na(125)I was added to suspensions of guinea pig granulocytes in Krebs-Ringer phosphate buffer, and they were then permitted to phagocytize different particles. Phagocytic vesicles were formed by allowing cells to ingest a paraffin oil emulsion (POE) and collected by flotation on sucrose after homogenization. Measurement of (125)I bound to TCA precipitates of the different fractions and the homogenates disclosed that the lysosome-rich fraction obtained by centrifugation from control (nonphagocytizing) cells accounted for a mean 93.1% of the total cellular activity. With phagocytosis of POE, TCA-precipitable iodination increased two- to sevenfold, and the lysosomal contribution fell to a mean 36.9% of the total. The appearance of activity within phagocytic vesicles accounted for almost the entire increase seen with phagocytosis (a mean 75.7%), and iodide was bound within these structures with high specific activity. More iodide was taken up by cells than fixed, regardless of iodide concentration, and was distributed widely throughout the cell rather than selectively trapped within the vesicles. The amount of iodide taken up and fixed varied considerably with the phagocytic particle employed. Yeast particles were found to stimulate iodination to a far greater degree than the ingestion of POE or latex. Such observations are consistent with the concept that the ingested particle is a major recipient of the iodination process. Measurements of metabolic activities related to the formation and utilization of peroxide by cells phagocytizing different particles were made and correlated with iodination. The findings suggest that mechanisms must exist within granulocytes to collect or perhaps even synthesize H(2)O(2) within phagocytic vesicles to serve as substrate for myeloperoxidase. The simultaneous stimulation of other metabolic pathways for peroxide disposal and its release into the medium by phagocytizing cells is consistent with the high diffusability of this important bactericidal substance.

H2O2 release from human granulocytes during phagocytosis. Relationship to superoxide anion formation and cellular catabolism of H2O2: studies with normal and cytochalasin B-treated cells.

Normal and cytochalasin B-treated human granulocytes have been studied to determine some of the interrelationships between phagocytosis-induced respiration and superoxide and hydrogen peroxide formation and release into the extracellular medium by intact cells. By using the scopoletin fluorescent assay to continuously monitor extracellular hydrogen peroxide concentrations during contact of cells with opsonized staphylococci, it was demonstrated that the superoxide scavengers ferricytochrome c and nitroblue tetrazolium significantly reduced the amount of H(2)O(2) released with time from normal cells but did not abolish it. This inhibitory effect was reversed by the simultaneous addition of superoxide dismutase (SOD), whereas the addition of SOD alone increased the amount of detectable H(2)O(2) in the medium. The addition of sodium azide markedly inhibited myeloperoxidase-H(2)O(2)-dependent protein iodination and more than doubled H(2)O(2) release, including the residual amount remaining after exposure of the cells to ferricytochrome c, suggesting its origin from an intracellular pool shared by several pathways for H(2)O(2) catabolism. When cells were pretreated with cytochalasin B and opsonized bacteria added, reduced oxygen consumption was observed, but this was in parallel to a reduction in specific binding of organisms to the cells when compared to normal. Under the influence of inhibited phagosome formation by cytochalasin B, the cells released an increased amount of superoxide and peroxide into the extracellular medium relative to oxygen consumption, and all detectable peroxide release could be inhibited by the addition of ferricytochrome c. Decreased H(2)O(2) production in the presence of this compound could not be ascribed to diminished bacterial binding, decreased oxidase activity, or increased H(2)O(2) catabolism and was reversed by the simultaneous addition of SOD. Furthermore, SOD and ferricytochrome c had similar effects on another H(2)O(2)-dependent reaction, protein iodination, in both normal and cytochalasin B cells. When oxygen consumption, O(2.) (-), and H(2)O(2) release were compared in the presence of azide under identical incubation conditions, the molar relationships for normal cells were 1.00:0.34:0.51 and for cytochalasin B-treated cells 1.00:0.99:0.40, respectively. Nonopsonized, or opsonized but disrupted, bacteria did not stimulate any of these metabolic functions. The results indicate that with normal cells approximately 50% of H(2)O(2) released during phagocytosis is derived directly from O(2.) (-) by dismutation, the remainder appearing from an (intra)cellular source shared by azide-inhibitable heme enzymes. With cytochalasin B treatment the evidence is consistent with the derivation of all H(2)O(2) from an O(2.) (-) precursor which is released from the cell surface. Furthermore, when activated by phagocytic particle binding, the neutrophil O(2.) (-) generating system appears to make more of this compound than can be accounted for by dismutation to H(2)O(2). This establishes conditions for the direct participation of both compounds in the microbicidal and cytocidal activity of these cells.

H2O2 release from human granulocytes during phagocytosis. I. Documentation, quantitation, and some regulating factors.

The extinction of fluorescence of scopoletin during its oxidation by horseradish peroxidase (HPO) provides a highly sensitive and specific assay for small quantities of peroxide in solution. With this assay, the release of free H2O2 into the extracellular medium by phagocytizing human granulocytes has been documented and quantitated, and some of the regulating factors have been determined. Under basal conditions granulocytes released less than 0.01 nmol/ml of H2O2 (2.5 X 10-6 polymorphonuclear leukocytes/ml). Upon the addition of phagocyte particles (latex, opsonized yeast, or staphylococci), an abrupt increase in extracellular peroxide concentration was observed (greater than 50-fold above basal levels) after latencies as short as 10 s. Release reflected increased intracellular H2O2 production during phagocytosis in that it paralleled the respiratory burst and was absent when phagocytosis was prevented or when cells from patients with chronic granulomatous disease were utilized. Evidence that scpoletin oxidation occurred predominantly in the extracellular medium was obtained by demonstrating a marked inhibition when HPO was omitted from the reaction mixture or when exogenous catalase was added. Similarly, it was found that exogenous serum also inhibited scopoletin oxidation, apparently because of the presence of competing hydrogen donors. H2O2 formation and release were observed at rates which closely paralleled those of phagocytosis. With O2 consumption as an approximate index of H2O2 formation, the fractions released during maximal rates of particle uptake were calculated as follows: for latex, 15.7%; for staphylococci, 10.3%; and for yeast, 4.9%. It is postulated that release is due to diffusion of free H2O2 from an expanded intracellular pool of this substance that develops during phagocytosis. This poos represents tha net of increased synthesis versus catabolism by various enxymatic pathways for H2O2 disposal within the cells. The close relationship between rates of H2O2 formation and rates of phagocytosis by human granulocytes suggests a role for specialized areas of the cell membrane, involved in particle ingestion, in the trigger mechanism for H2O2 synthesis. The consequences of H2O2 release to other cells or organisms in the immediate environment of phagocytizing granulocytes remain to be determined.

Biochemical and immunologic analysis of hereditary myeloperoxidase deficiency.

Myeloperoxidase (MPO), a heme enzyme present in the azurophilic granules of human polymorphonuclear neutrophils (PMN), is important in the oxygen-dependent microbicidal activity of PMN. MPO deficiency, defined as the lack of PMN peroxidative activity, is a common genetic defect of human PMN. The purpose of our study was to characterize the structural basis for this loss of enzymatic activity, using protein biochemical and immunochemical techniques to examine PMN from three subjects with partial MPO deficiency and from five subjects with complete MPO deficiency.We purified MPO from normal PMN and defined its electrophoretic mobility after two-dimensional electrophoretic separation, using nondenaturing acidic polyacrylamide gel electrophoresis (PAGE) followed by sodium dodecyl sulfate (SDS) denaturation and SDS-PAGE separation of MPO subunit peptides. In agreement with previous studies, we found that normal MPO had subunits of 59,000 and 13,500 mol wt when subjected to SDS-PAGE under reducing conditions. Granule protein extracts of normal PMN, partially MPO-deficient PMN, and completely MPO-deficient PMN were analyzed with two-dimensional PAGE. Partially MPO-deficient PMN granules contained electrophoretically normal MPO in less than normal amounts, whereas completely MPO-deficient PMN granules contain no protein with the electrophoretic mobility of normal MPO. Using rabbit antiserum against purified MPO, we used immunoautoradiographic analysis to examine whole PMN for peptides immunochemically related to MPO. PMN from normal, partially MPO-deficient, and completely MPO-deficient subjects were solubilized in SDS and component peptides separated by SDS-PAGE. The peptides were electroblotted onto nitrocellulose paper that was exposed sequentially to rabbit anti-MPO and (125)I-protein A before autoradiography. Radiolabeled bands were identical when partially purified MPO or normal PMN were compared except that whole PMN contained a small amount of an immunologically cross-reactive membrane associated material of 75,000-90,000 mol wt. Using a modification of this immunoautoradiographic analysis, we quantitated the relative amounts of MPO peptides in PMN. PMN from MPO-deficient subjects contain 41.0-52.3% the amount of MPO peptides present in normal PMN. Similar analysis showed that completely MPO-deficient PMN lacked any peptides corresponding to MPO peptides.We conclude that partial MPO deficiency is characterized by the presence of electrophoretically and immunologically normal MPO in amounts approximately one-half that seen in PMN from normal subjects. Completely MPO-deficient PMN lack any normal MPO peptides. No MPO-deficient subject studied had an immunologically cross-reacting variant of MPO. Since this deficiency is associated with the absence of more than one peptide, it is possible that the underlying genetic defect may involve: (a) failure to synthesize a single precursor peptide; (b) abnormal regulation of the synthesis of two separate peptides; or (c) an aberration in postsynthetic processing or packaging into azurophilic granules.

Leukocytic function in hypogammaglobulinemia.

The phagocytic, bactericidal, and metabolic capabilities of circulating blood leukocytes from three adults (two males, one female) with hypogammaglobulinemia and recurrent pneumonia, chronic sinusitis, and intestinal giardiasis were studied. These functions were found to be normal when leukocytes from the patients were incubated in media containing normal human serum. Phagocytosis of Staphylococcus albus and polystyrene balls by both patient and normal leukocytes was diminished when the cells were incubated in hypogammaglobulinemic plasma. A similar defect in opsonization by patient plasma was also noted for pneumococci, Escherichia coli and variably with Staphylococcus aureus. Both patient and normal sera had equivalent levels of heat-labile S. albus opsonins; normal serum, however, contained heat-stable S. albus-specific absorbable opsonins in significantly greater quantities to account for its superior opsonic capacity. The addition of commercial gamma globulin or purified IgG to hypogammaglobulinemic sera restored full S. albus opsonic activity. The relevancy of these observations to the impaired host defenses in these patients will be discussed.

Abnormal bactericidal, metabolic, and lysosomal functions of Chediak-Higashi Syndrome leukocytes.

Phagocytic, antimicrobial, and metabolic functions were studied in leukocytes obtained from three patients with the Chediak-Higashi syndrome (CHS) and compared to normals, individuals, heterozygous for Chediak-Higashi syndrome, and two subjects with chronic granulomatous disease of childhood (CGD). Chediak-Higashi syndrome leukocytes showed normal ingestion of a variety of bacteria, Candida albicans, and polystyrene latex particles. Intracellular destruction was significantly impaired for Staphylococcus aureus, Group D streptococci, and a rough strain of Type II pneumococci over a 2 hr incubation. Killing of Serattia marcescens was consistently delayed at 1 hr whereas that of Escherichia coli and C. albicans appeared normal, unless the incubations were shortened to 20 min. Examination of the rates of killing indicated that the greatest defect occurred in the first 20 min of contact between Chediak-Higashi syndrome cells and bacteria. Separation of Chediak-Higashi syndrome granulocytes from monocytes revealed that the former were most defective in bactericidal activity. After phagocytosis, Chediak-Higashi syndrome granulocytes displayed a normal burst in oxygen consumption and oxidation of glucose-1-(14)C and glucose-6-(14)C and formate-(14)C. Oxidation of glucose-1-(14)C by non-phagocytizing Chediak-Higashi syndrome granulocytes and monocytes averaged 2-3 times normal, whereas glucose-6-(14)C and formate-(14)C oxidation were not significantly increased by resting cells. Iodination of intracellular protein by Chediak-Higashi syndrome leukocytes was significantly increased above normal in both the resting and phagocytizing state. Electron microscopic histochemistry revealed that almost all peroxidase activity was localized to the giant granules in Chediak-Higashi granulocytes, and after bacterial ingestion there was a failure of delivery of peroxidase to many phagosomes. Upon longer incubation more phagosomes acquired peroxidase activity, presumably through a fusion process, although many giant granules remained intact. The contrasting patterns and kinetics of the killing defects and the differing metabolic properties of Chediak-Higashi syndrome and chronic granulomatous disease leukocytes emphasize the pleiomorphic nature of inherited disorders of leukocyte function.

Effects of oxygen exposure on it vitro function of pulmonary alveolar macrophages.

Bacterial infection may complicate pulmonary oxygen (O2) toxicity, and animals exposed to high O2 concentrations show depressed in vivo pulmonary bacterial inactivation. Therefore, in vitro studies were undertaken to define the mechanism by which O2 alters pulmonary antibacterial activity. Normal and BCG pretreated rabbits were exposed to 100% O2 for 24, 48, and 72-h periods. Pulmonary alveolar macrophages (PAM) were obtained from the experimental animals and from nonoxygen exposed controls by bronchopulmonary lavage. O2 exposure did not alter cell yield or morphology. PAMs were suspended in 10% serum-buffer, and phagocytosis of (14C)Staphylococcus aureus 502A and (14C)Pseudomonas aeruginosa was measured. Comparison of the precent uptake of the 14C-labeled S. aureus after a 60-min incubation period demonstrated that normal PAMs exposed to O2 for 48 h showed a statistically significant increase in phagocytosis when compared to their controls (43.5 vs. 29.2%). A similar, but smaller increase was seen after 24-h O2 exposures. 48 and 72-h O2 exposures produced no significant changes in phagocytosis in PAMs from BCG-stimulated rabbits. Normal PAMs also showed an increased phagocytosis of Ps. aeruginosa after 48-h oxygen exposure. No impairment of in vitro bactericidal activity against either S. aureus 502A or Ps. aeruginosa could be demonstrated in PAMs from normal rabbits exposed to O2 for 48 h. These results indicate that the in vitrophagocytic and bactericidal capacity of the rabbit PAM is relatively resistant to the toxic effects of oxygen, and that imparied in vivo activity may possibly be mediated by effects other than irreversible metabolic damage to these cells. The mechanism for the observed stimulation of phagocytosis remains to be determined.

Interactions between antibiotics and human neutrophils in the killing of staphylococci.

Normal and antibiotic-pretreated staphylococci were incubated with human neutrophils to determine the interactions between cells and antimicrobials in the killing of the organisms. Staphylococcus aureus 502A pretreated during log-phase growth with subinhibitory ((1/4) minimum inhibiting concentration) (MIC) concentrations of penicillin G were more susceptible to killing by normal neutrophils than untreated bacteria (intracellular survival 0.17+/-0.04 vs. 1.5+/-0.38%, mean+/-SEM, respectively, at 35 min in 14 experiments; P < 0.01 by t test). Furthermore, this enhanced susceptibility to killing was observed even when phagosome formation was inhibited by cytochalasin B (65.6+/-4.6% pencillintreated vs. 30.5+/-4.5% untreated killed at 30 min in 14 experiments, P < 0.001). Pretreatment of S. aureus with vancomycin similarly enhanced susceptibility to killing by cytochalasin B-treated polymorphonuclear leukocytes (PMN), whereas pretreatment with gentamicin did not. The enchancement of killing by pretreatment with cell wall-active antibiotics was present in a dose-response fashion to 1/16th the MIC. It required specific antimicrobial activity; i.e., penicillin activity was inhibited by penicillinase or by incubation with bacteria at 4 degrees C. It also required active cellular metabolism and intact neutrophils. For antibiotic-pretreated bacteria to be killed by normal and cytochalasin B-treated cells, phagocytosis or binding to the cells was essential via a serum opsonindependent mechanism. In experiments with the cytochalasin B-treated cells, all bound penicillin-treated bacteria were killed vs. only a fraction (70%) of the bound untreated bacteria. Penicillin in 10 times the MIC had no direct effects on PMN phagocytic, metabolic, or microbicidal functions against a nonsusceptible organism, Candida albicans. The results indicate a cooperative effect between cell wall-active antibiotics at low concentrations and human PMN in the killing of staphylococci. The model establishes conditions for the study of the mechanisms involved in the cooperation of these bactericidal systems.

Inhibition of human granulocyte function by methotrexate.

Patients receiving cytotoxic drugs are at an increased risk of bacterial infection. Drug-induced leukopenia may be responsible for depression of host defenses; however, there is little information concerning the qualitative effects, if any, of cytotoxic agents on granulocyte antibacterial activity. Since methotrexate is now being used in massive doses in vivo, we investigated the effects of this drug on antibacterial and metabolic functions of normal polymorphonuclear leukocytes in vitro. Phagocytosis, quantitative protein iodination, and staphylococcal killing of normal polymorphonuclear leukocytes were found to decrease with exposure to increasing concentrations of methotrexate. The effects of methotrexate on these cell functions were rapid in onset and readily reversed by washing the cells, suggesting a locus of action on the cell membrane rather than at the level of nucleic acid synthesis. Exposure of cells to similar concentrations of folic acid or folinic acid produced no impairment of bacterial phagocytosis, suggesting that the observed effects are specific for methotrexate. The concentrations of methotrexate that produced these impairments are readily achieved in vivo and may alter antibacterial defenses in patients receiving this therapy.

Respiratory syncytial virus infections on an adult medical ward.

Eleven cases of respiratory syncytial virus (RSV) infection occurred in acutely ill hospitalized adults over a 7-week period. Nosocomial illness was suspected in two patients. Because RSV can cause serious infections in immunocompromised adults with the potential for nosocomial spread, the following recommendations are indicated: (1) during the winter months, early recognition and diagnosis of RSV infections both in hospital staff and in patients should be encouraged; (2) infected hospital personnel should avoid patient contact when possible; (3) during outbreaks, careful attention must be paid to hand washing and gloving; and (4) a high level of vigilance for RSV infection should be maintained on units with immunocompromised patients. Increased awareness of the potential risks of RSV infection is needed on adult medical units.

Enterococcal meningitis: combined vancomycin and rifampin therapy.

Intrathecal vancomycin and oral rifampin have been used together to successfully treat a patient with enterococcal meningitis who was allergic to penicillin and who had failed a course of treatment with chloramphenicol. This therapy was tolerated very well and represents an alternate mode of therapy which should be considered in penicillin allergic patients with enterococcal meningitis.

Fungal infection in chronic granulomatous disease. The importance of the phagocyte in defense against fungi.

Among 245 cases of chronic granulomatous disease which were evaluated, fungal infection occurred in 20.4 percent. Fungi encountered include Aspergillus, Torulopsis and Candida. In 18 percent of the patients with fungal infection, the disease was limited to soft tissue or bone; all did well. Most of the patients had fungal pneumonia and/or widely disseminated disease; diagnosis was usually confirmed by open lung biopsy. Patients with pneumonia or disseminated disease who received no therapy succumbed to infection, whereas more than half the patients who received antifungal therapy were cured. Modalities of treatment included antifungal chemotherapy, surgical removal of infected tissue and granulocyte transfusion. Although several patients showed dramatic improvement during granulocyte transfusions given in combination with antifungal chemotherapy, the improvement achieved was not statistically significant when compared with that achieved with chemotherapy alone. These results emphasized the importance of phagocytic cells in defense against fungi and the need for further evaluation of granulocyte transfusion therapy in compromised hosts in whom fungal infections develop.

Indium-111-labeled human polymorphonuclear leukocytes: viability, random migration, chemotaxis, bacterial capacity, and ultrastructure.

Human polymorphonuclear leukocytes (PMNs) were labeled with indium-111 oxine in ethanol, and the effects of the labeling procedure, radioactivity, and concentrations of oxine and ethanol on PMN function and structure were studied in vitro. The standard labeling procedure did not alter the viability, random migration, chemotaxis, bactericidal capacity, or the ultrastructure of PMNs. Exposure to higher doses of radioactivity, or to higher concentrations of ethanol, had no appreciable effects on random migration and chemotaxis of PMNs. A dose-dependent reduction in their random migration and chemotaxis was observed when higher concentrations of oxine were used. These results indicate that In-111-labeled PMNs are structurally intact and have normal in vitro locomotion and bactericidal activity. Indium-111-labeled PMNs should be suitable for studying the kinetics and distribution of these cells in health and disease.

Host-defense mechanisms in hidradenitis suppurativa.

Host-defense mechanisms were studied in seven patients with active hidradenitis suppurativa (HS). Granulocyte phagocytic function was measured by ingestion of Staphylococcus aureus labeled with radioactive carbon 14 and intracellular killing was determined by bactericidal pour plate method. Chemotaxis was measured by radioactive counting of sodium chromate Cr 51 granulocytes migrating in modified Boyden chambers. Granulocyte adherence was estimated in vitro by filtering blood samples through nylon fiber columns. Cell-mediated immunity was measured by intradermal delayed hypersensitivity responses to Candida, mumps. streptokinase/streptodornase, and purified protein derivative antigens. No abnormality was demonstrated in any granulocyte or cell-mediated immune function tests. Moreover, all patients had normal immunoglobulin levels and elevated total hemolytic complement. Therefore, we conclude that HS is a localized chronic infection of apocrine glands without a generalized defect in host defense.

Leukocyte adhesion proteins: their role in neutrophil function.

In conclusion, the leukocyte proteins of the CD11/18 complex are highly conserved members of the integrin family in mammalian species. They play a key role in phagocytic and adherence mediated activities of neutrophils and appear to be centrally involved in adhesion to endothelial cells as well as transendothelial migration. Their importance in these processes has been documented by the occurrence of the disease now called leukocyte adhesion deficiency and the functional effects of a variety of monoclonal antibodies directed at different epitopes on the heterodimeric glycoprotein chains. These antibodies, as well as those directed at endothelial cell ligands for leukocyte adhesion proteins or peptides which mimic the functional epitopes, offer opportunities to manipulate or modify the inflammatory response in vivo where neutrophil accumulation or action can be harmful. They can also be employed to dissect out the role of PMNs in various repair processes such as wound healing. While bone marrow transplantation can ameliorate the deleterious consequences of severe LAD, continued elucidation of the multiple molecular mechanisms responsible for this disease will pave the way for its future genetic correction.