Immunologic defects and vaccination in patients with chronic renal failure.

Patients with chronic renal failure suffer from defective host defenses which are directly the result of the renal impairment, in addition to those dependent on the primary illness leading to the renal failure. The mechanisms underlying the defective responses in phagocytic cells, lymphocytes and antigen processing are likely due to either failure to adequately eliminate suppressive compounds by the defective kidneys or to improper metabolic processing of the factors by the damaged renal parynchema. That some of the defects are reversed by transplantation and not dialysis suggests that renal parenchymal metabolic activities may be involved, although it is also possible that functioning glomerular cells are capable of filtering substances that membranes are not currently capable of eliminating. The current strategy for dealing with the immunodeficiency appears to be totally based on developing means to circumvent the defective function. The other approach, correction of the impaired function, cannot be even considered until the mechanisms underlying the defective function of the cells involved in defenses are better delineated. It seems possible that one or a few compounds are pivotal in altering the function of all the affected cell lines, since, with only a small amount of effort, it is possible to relate the dysfunction to abnormal cell membrane functions in phagocytic cells, dendritic cells and lymphocytes. Until the biochemical basis of the dysfunction of all the cell types affected are better defined, such exercises cannot be translated into better management of patients with chronic renal failure. Proper function of host defenses requires that appropriate cells can properly respond to threats to host viability. For the cells of the immune system (phagocytes and lymphocytes) this means that their response to regulatory molecules be appropriate, that their mobility be normal, that their adherence to substrates be preserved, and that they can generate the appropriate response to the challenge. For neutrophils, for example, it is necessary that they recognize and mobilize appropriately to chemotactic stimuli, that they be able to adhere to and migrate through endothelial lining, that their phagocytic activity be sufficient, and that they can kill and degrade endocytosed particles and generate appropriate secretions. Similar lists of requirements for good function can be generated for any cell type in the immune defense system. Uremia, as well as currently available treatments for uremia, directly or indirectly alters the function of all phases of appropriate immune cell function. Defective host responses in uremia have been recognized for decades and there has been considerable effort in the past decade to better define the extent and mechanisms of impaired defenses. Despite the multitude of major defects in humoral, cellular, and inflammatory processes, uremic patients who are cared for today, although they remain at higher risk of serious infectious complications, can and do maintain a good quality of life, with most remaining free of major infections for years and decades.

Osteoclasts and effects of interleukin 4 in development of chronic osteomyelitis.

The cellular response to trauma and infection was studied in a murine model of posttraumatic osteomyelitis. Osteoclast response differed markedly depending on whether infection with Staphylococcus aureus accompanied the bone trauma. In animals recovering from sterile trauma, osteoclastic activity that was limited to the damaged or dead bone fragments caused rapid elimination of all recognizable dead bone within 1 week. New bone was laid down in an orderly fashion. Animals with superimposed infection had an intense polymorphonuclear leukocyte response develop. Additionally, osteoclasts behaved as acute inflammatory responders with substantial activity at the margins of the infected site and at previously uninjured tibial cortex adjacent to the infection. Despite the exuberant osteoclast response, bony fragments were not resorbed (for at least 4 weeks after the trauma), that is, sequestra developed, and new bone was laid down over morphologically dead bone and on the cortex (involucrum). When the inhibitory cytokine, interleukin 4 was given in a single dose with the bacterial inoculum, the osteoclast response was moderated with almost complete elimination of osteoclast activity at normal tibial cortex adjacent to the infected site. The limitation of osteoclastic activity did not impair the host's containment of bacterial growth.

Mantle-cell lymphoma in a patient with human immunodeficiency viral infection.

Rare cases of low-grade lymphomas have been described in patients with human immunodeficiency virus (HIV) infection. However, this is the first reported case of mantle-cell lymphoma, a type of low-grade lymphoma, in a patient who also had HIV infection. Salient clinical features included lymphocytosis, lymphadenopathy, splenomegaly, and involvement of the bone marrow and meninges. The disease proved to be unusually aggressive and response to chemotherapy was insignificant. The patient survived only 4 months.

Intravenous immunoglobulin therapy for toxic shock syndrome.

Staphylococcus aureus and group A Streptococcus pyogenes produce toxic shock syndrome characterized by hypotension and multisystem organ failure. While conventional therapy has consisted of antibiotics and intensive supportive care, some experimental evidence suggests that immunoglobulins directed against the toxins may be effective additional therapy. We report a case of "toxic strep syndrome" in which intravenous immunoglobulin was administered when signs and symptoms were worsening while the patient was receiving conventional therapy. Within hours of administration of the intravenous immunoglobulin, the patient experienced dramatic clinical improvement. This response suggests a possible therapeutic benefit of intravenous immunoglobulin in toxic shock syndrome.

Binding of 125I-labelled tumor necrosis factor to Pneumocystis carinii and an insoluble cell wall fraction.

We have previously shown that tumor necrosis factor-alpha (TNF-alpha) causes loss of viability of Pneumocystis carinii. In this study, we demonstrate that TNF-alpha irreversibly binds to P. carinii in vitro. The avidity of binding is orders of magnitude greater than that by which it binds to a known sensitive target, L929 cells. A detergent-insoluble fraction of P. carinii, which consists primarily of cyst walls, bound ten times more TNF-alpha per microgram protein as did whole P. carinii.

Interaction of cytokines and alveolar cells with Pneumocystis carinii in vitro.

Although deficient cellular immune function is a major predisposing factor in the development of Pneumocystis carinii pneumonia, the mechanisms involved in cellular immune surveillance against P. carinii have not been defined. When P. carinii were separated from rat cells by a semipermeable membrane, alveolar macrophages secreted substances lethal to P. carinii only when the macrophages were activated by interferon-gamma; normal macrophages were ineffective. Type II alveolar epithelial cells caused death of P. carinii whether or not interferon-gamma was present. The effects of soluble mediators also were tested; recombinant human tumor necrosis factor-alpha (TNF) but not recombinant rat interferon-gamma or endotoxin was directly lethal to P. carinii. These lethal effects were prevented when antiserum to TNF or antioxidants (catalase and superoxide dismutase) were included. These data suggest that TNF may be a major mediator involved in the killing activity of activated macrophages against P. carinii and that TNF's activity against P. carinii is related to induction of oxidative stresses.

Glycoproteins of Pneumocystis carinii: characterization by electrophoresis and microscopy.

Glycoproteins are integral components of cell-surface structure and participate in adherence of pathogenic microbes to host cells. We have initiated studies of the glycoproteins of Pneumocystis carinii. Biotin-conjugated lectins, followed by reaction with avidin-peroxidase, were used to detect glycoproteins in electrophoretically separated proteins of P. carinii and on whole organisms when using light microscopy. Glycoproteins of P. carinii were clearly different from rat cell glycoproteins. Multiple glycoproteins were present in P. carinii and exhibited intense reactivity to both concanavalin A and wheat-germ agglutinin. Those lectins that reacted with the electrophoretically separated proteins also stained both alcohol-fixed P. carinii and the extracellular granular material present only in P. carinii preparations. In electron micrographs of P. carinii, which were stained with colloidal-gold-labeled concanavalin A, we found that the lectin bound to the outer surface of the organisms and to the tubular extensions emanating from the exterior surface.

Rapid separation of Pneumocystis carinii from lung lavage fluids.

A simple, rapid procedure to separate Pneumocystis carinii obtained by lavage of lungs of steroid-treated rats from rat leukocytes is described. Commercially available monoclonal antibody to rat common leukocyte determinants is used to sediment the leukocytes, resulting in supernatant fluid containing P. carinii cells virtually free of intact rat cells.

Intrapulmonary growth of Staphylococcus aureus in rats during induced atelectasis.

Intrinsic pulmonary antibacterial defenses are mediated by alveolar macrophages and by noncellular factors. Mechanical ventilation in the resting tidal volume range leads to alterations in the physical characteristics of alveolar surfactant, alveolar instability, regional hypoxia, and systemic hypoxemia. While a number of experimental manipulations diminish the activity of the intrinsic antibacterial defense system, the effects of mechanical ventilation per se have not been systematically evaluated previously. We found that normal rats ventilated without sighing (periodic large breaths) manifested severe defects in pulmonary clearance of Staphylococcus aureus during 6-h experiments, such that growth of the inoculum occurred. Addition of a timer-controlled mechanism to cause the animals to sigh every 2 min, without other modifications in the experimental conditions, caused significant improvement in clearance. Analysis of cellular response, compartmentalization of viable bacteria, surfactant quantities and sedimentation characteristics, and protein influx indicated that the defect in clearance paralleled alterations in the physical state of surfactant and alveolar stability but was not strongly correlated with alterations in the other parameters we measured. The data show that defective pulmonary bacterial clearance is rapidly induced by measures which alter alveolar stability and suggest that intrinsic pulmonary defenses require maintenance of normal air-liquid interfaces for optimal function.

Phospholipid profile of Pneumocystis carinii and its interaction with alveolar type II epithelial cells.

Pneumocystis carinii is an obligate parasite of mammalian lungs, attaching to but not invading the alveolar epithelium. The alveolar air spaces are rich in phospholipids, which are secreted by steroid-responsive alveolar type II epithelial cells. P. carinii isolated from rat lungs was found to contain the expected structural phospholipids as well as a large amount of firmly attached disaturated phosphatidylcholine, the characteristic phospholipid of alveolar surfactant. In vitro, P. carinii cells synthesized phospholipids from simple radiolabeled precursors; disaturated phosphatidylcholine was not formed. However, washed P. carinii cells avidly adsorbed radiolabeled rat surfactant, a process that appeared to be saturable, not dependent on viability of the organisms, and abolished by incubation at 4 degrees C. The surfactant was neither harmful nor beneficial to in vitro survival of the organisms. With the exception of high concentrations of arachidonic acid, fatty acids found in rat alveolar lining material were also not toxic. In addition, cultures consisting primarily of rat type II alveolar epithelial cells were toxic to P. carinii when the organisms were added to monolayers of type II cells at less than or equal to 10:1 multiplicity. At higher multiplicities, the parasite survived (but did not increase in numbers), and the type II cells deteriorated. The mechanism for this effect has not been determined.

Murine cytomegalovirus adrenalitis in athymic nude mice.

During studies of the pathogenesis of murine cytomegalovirus (MCMV) infection in athymic nude mice, we noted striking virus involvement of the adrenal glands. Because patients with the acquired immunodeficiency syndrome (AIDS) have recently been reported to have adrenal necrosis and evidence of infection of the adrenal gland with human cytomegalovirus (HCMV), we have further evaluated adrenal gland involvement during MCMV infection. Following virus inoculation, MCMV replicated to high titer in the adrenal glands of T-cell deficient, homozygous nude mice, but not heterozygous littermates with intact T-cell function. Concomitant with the high titers of virus, there appeared overt histological evidence of herpes-virus virus infection accompanied by patchy necrosis of adrenal cortical and medullary tissues. Acyclovir, which inhibits growth of MCMV, reduced virus replication in the adrenal gland. Similarly, virus replication was diminished in homozygous nude mice immunologically reconstituted by infusion of normal spleen cells three weeks prior to infection. Thus, in the absence of functioning T lymphocytes, MCMV can infect and replicate in adrenal tissues causing a progressive destructive adrenalitis.

Modulation of pulmonary clearance of bacteria by antioxidants.

To further delineate the mechanisms underlying murine pulmonary defenses against bacterial infection, we studied the effects of antioxidant enzymes and hydroxyl radical scavengers on pulmonary clearance processes. Intratracheal injection of catalase and superoxide dismutase resulted in prolonged intraalveolar residence of the enzymes, but caused no decrease in rates of clearance of either Staphylococcus aureus 502A or Pseudomonas aeruginosa PAO1. In contrast, dimethylsulfoxide and dimethylthiourea caused significant depression of clearance of P. aeruginosa without altering clearance of S. aureus. These results provide further differentiation between clearance processes affecting gram-negative and gram-positive bacteria and suggest that murine clearance of gram-negative organisms may be in part mediated by reactions which generate hydroxyl anion. In vivo administration of agents which inhibit hydrogen peroxide-, superoxide-, or hydroxyl anion-mediated reactions do not alter normal clearance of S. aureus.

The relation of viral replication to interstitial pneumonitis in murine cytomegalovirus lung infection.

Using a murine model of murine cytomegalovirus (MCMV) interstitial pneumonitis, we examined the relation between the virus content of the lung and lung disease. While MCMV alone does not cause lung disease, interstitial pneumonitis was present in all mice receiving both MCMV and a single dose of cyclophosphamide. In this case the severity of disease, judged by increases in wet weight of the lung, was proportional to the virus content of the lung. Although both acyclovir (50 mg/kg per day) and passive antibody administration reduced the MCMV titers in lung tissues by greater than 90%, histological evidence of interstitial pneumonitis was present in all animals. However, both virus inhibitors reduced the severity of interstitial pneumonitis in treated mice. While transient alterations in host immunity are necessary to induce interstitial pneumonitis after MCMV infection, the severity of interstitial pneumonitis seems to reflect the burden of virus replication. Reduction of virus growth does not prevent, but may moderate, MCMV interstitial pneumonitis.

Murine cytomegalovirus-induced macrophage dysfunction.

Macrophages infected in vitro with murine cytomegalovirus (MCMV) manifest depressed phagocytic uptake of a variety of particles within hours after the initiation of infection. Analysis of kinetics of uptake of radiolabeled Staphylococcus aureus by MCMV-infected macrophages indicates that the diminished uptake results from a depression in the calculated maximum velocity of uptake (Vmax) with the apparent Michaelis constant (KM) remaining unaltered. This pattern of altered uptake is typical of that seen after manipulations that affect the surface interactions of macrophages with ingestible particles. Coincubation of macrophages and radiolabeled Staphylococcus with opsonizing antibody resulted in normalization of the phagocytic rates. The surface localization of the defective phagocytosis was further confirmed by light and scanning electron microscopy of the macrophages incubated with Staphylococcus or latex spherules. These data indicate that defective macrophage surface that interferes with the initial macrophage-particle interactions that initiate nonimmune phagocytosis.