Diverse activity of human secretory phospholipases A2 on the migration of human vascular smooth muscle cells.

OBJECTIVE: Investigation of the diversity of human secretory phospholipases A2 (sPLA2) on the migration of human vascular smooth muscle cells (VSMC). MATERIAL: We investigated the impact of sPLA2 IIA, V, and X and of oleic acid, linoleic acid and lysophosphatidylcholine on the migration of human VSMC. METHODS: Recombinant human sPLA2's and Boyden's chamber method were applied. RESULTS: sPLA2, IIA but not V or X enhanced migration of VSMC in a dose/time dependent manner. Oleic and linoleic acids, and lysophosphatidylcholine markedly enhanced migration. CONCLUSIONS: These results imply that sPLA2 IIA, which is known to be present in the arterial wall in the vicinity of VSMC, as well as products of lipid hydrolysis induced by sPLA2, enhance the migration of VSMC, and thus may contribute to atherogenic process.

Hydrolysis of minor glycerophospholipids of plasma lipoproteins by human group IIA, V and X secretory phospholipases A2.

We investigated the hydrolysis of the minor glycerophospholipids of human HDL(3), total HDL and LDL using human group IIA, V and X secretory phospholipases A(2) (sPLA(2)s). For this purpose we employed the enzyme and substrate concentrations and incubation times optimized for hydrolysis of phosphatidylcholine (PtdCho), the major glycerophospholipid of plasma lipoproteins. In contrast to PtdCho, which was readily hydrolyzed by group V and X sPLA(2)s, and to a lesser extent by group IIA sPLA(2), the minor ethanolamine, inositol and serine glycerophospholipids exhibited marked resistance to hydrolysis by all three sPLA(2)s. Thus, when PtdCho was hydrolyzed about 80%, the ethanolamine and inositol glycerophospholipids reached a maximum of 40% hydrolysis. The hydrolysis of phosphatidylserine (PtdSer), which was examined to a more limited extent, showed similar resistance to group IIA, V and X sPLA(2)s, although the group V sPLA(2) attacked it more readily than group X sPLA(2) (52% versus 39% hydrolysis, respectively). Surprisingly, the group IIA sPLA(2) hydrolysis remained minimal at 10-15% for all minor glycerophospholipids, and was of the order seen for the PtdCho hydrolysis by group IIA sPLA(2) at the 4-h digestion time. All three enzymes attacked the oligo- and polyenoic species in proportion to their mole percentage in the lipoproteins, although there were exceptions. There was evidence of a more rapid destruction of the palmitoyl compared to the stearoyl arachidonoyl glycerophospholipids. Overall, the characteristics of hydrolysis of the molecular species of the lipoprotein-bound diradyl GroPEtn, GroPIns and GroPSer by group V and X sPLA(2)s differed significantly from those observed with lipoprotein-bound PtdCho. As a result, the acidic inositol and serine glycerophospholipids accumulated in the digestion residues of both LDL and HDL, and presumably increased the acidity of the residual particles. An accumulation of the ethanolamine glycerophospholipids in the sPLA(2) digestion residues also had not been previously reported. These results further emphasize the diversity in the enzymatic activity of the group IIA, V and X sPLA(2)s. Since these sPLA(2)s possess comparable tissue distribution, their combined activity may exacerbate their known proinflammatory and proatherosclerotic function.

Serum and urinary proteins, lysozyme (muramidase), and renal dysfunction in mono- and myelomonocytic leukemia.

Serum levels, urinary excretion, and clearances of several proteins of different molecular weights were studied in 18 patients with mono- and myelomonocytic leukemia. Nine patients had normal renal function (group A) and nine had impaired renal function with azotemia (group B). The majority of patients in both groups had increased concentration of immunoglobulins, particularly IgG, IgA, and IgM; IgD level was normal. Serum transferrin and alpha(2)-macroglobulin were frequently reduced while the level of ceruloplasmin was often increased, especially in patients with azotemia. The activity of lysozyme in the serum was high in all patients, but was considerably higher in group B. Proteinuria was found in most patients but was more prominent in group B. Almost invariably albumin constituted less than 25% of the total protein excreted. Qualitative analysis of various urinary proteins by immunochemical techniques and clearance studies suggested the presence of glomerular as well as tubular dysfunction. Determination of urinary lysozyme frequently showed no direct correlation between the serum level of the enzyme and its concentration in the urine or its clearance by the kidney. In addition to glomerular filtration, impaired tubular reabsorption may account for the high level of lysozyme in the urine. It is postulated that the very high level of lysozyme in the glomerular filtrate and possibly hypergammaglobulinemia may play a role in the induction of tubular damage. Renal impairment has been correlated with histological changes in the kidneys. From a comparative study of various leukemias, it seems that the combined glomerular-tubular dysfunction is a manifestation unique to mono- and myelomonocytic leukemia.

Differential hydrolysis of molecular species of lipoprotein phosphatidylcholine by groups IIA, V and X secretory phospholipases A2.

Human groups IIA, V and X secretory phospholipases A2 (sPLA2s) were incubated with human HDL3, total HDL and LDL over a range of enzyme and substrate concentrations and exposure times. The residual phosphatidylcholines (PtdChos) were assayed by high performance liquid chromatography with electrospray ionization mass spectrometry (LC/ESI-MS). The enzymes varied markedly in their rates of hydrolysis of the different molecular species and in the production of lysoPtdCho. The sPLA2s were compared at a concentration of 1 microg/ml and an incubation time of 4 h, when all three enzymes showed significant activity. The groups V and X sPLA2 were up to 20 times more reactive than group IIA sPLA2. Group X sPLA2 hydrolyzed arachidonate and linoleate containing species preferentially, while group V hydrolyzed the linoleates in preference to polyunsaturates. In all instances, the arachidonoyl and linoleoyl palmitates were hydrolyzed in preference to the corresponding stearates by group X sPLA2. The group IIA enzyme appeared to hydrolyze randomly all diacyl molecular species. The minor alkylacyl and alkenylacyl glycerophosphocholines (GroPChos) were poor substrates for groups V and X sPLA2s and these phospholipids tended to accumulate. The present study demonstrates a preferential release of arachidonate from plasma lipoprotein PtdCho by group X sPLA2, as well as a relative resistance of polyunsaturated PtdChos to hydrolysis by group V enzyme, which had not been previously documented. The use of lipoprotein PtdCho as substrate with LC/ESI-MS identification of hydrolyzed molecular species eliminates much of the uncertainty about sPLA2 specificity arising from past analyses of fatty acid release from unknown or ill-defined sources.

Modulatory activity of chemotherapeutic agents on phagocytosis and intracellular bactericidal activity of human polymorphonuclear and mononuclear phagocytes.

Thirteen chemotherapeutic agents were tested for modulatory activity on phagocytosis by human granulocytes and monocytes. Phagocytosis, phagocytic index, and intracellular bactericidal activity were assessed using Staphylococcus aureus, smooth strain of Escherichia coli, and latex particles. Modulation of phagocytic activity depended on the type of particle used and the presence of serum in the medium. Testing granulocytes, only 1,3-bis(2-chloroethyl)-1-nitrosourea suppressed phagocytosis of all three types of particles used for ingestion. Other drugs suppressed either phagocytosis of E. coli and S. aureus or of one of the bacteria and latex particles. Three drugs enhanced ingestion of latex particles. The most pronounced modulation of phagocytosis was observed in conditions similar to those in vivo, namely, when serum was added to the medium and when the cells were exposed for longer time to the drugs. In the absence of serum, very little modulation of phagocytosis was observed, and only 1,3-bis(2-chloroethyl)-1-nitrosourea retained strong suppressive activity. Intracellular bactericidal activity was markedly suppressed by 7 of 13 drugs tested. Monocytes were less influenced by chemotherapeutic agents, their phagocytic activity being either suppressed or enhanced. The influence of chemotherapeutic agents on phagocytosis must be taken into consideration when assessing defense mechanisms and susceptibility to infection in patients with malignant diseases.

Regulation of the cellular expression of secretory and cytosolic phospholipases A2, and cyclooxygenase-2 by peptide growth factors.

Secretory group II (sPLA2) and cytosolic (cPLA2) phospholipases A2 and cyclooxygenase-2 (Cox-2) play a pivotal role in release of proinflammatory eicosanoids. Excessive activity of sPLA2 per se can also propagate inflammation. Endogenous control of the above enzymes has not been completely elucidated. We investigated the combined impact of promoting cytokines and inhibitory peptide growth factors on the expression of mRNA of the above enzymes, on protein content and extracellular release of sPLA2 and on PGE2 production in osteoblasts (FRCO). The synthesis and release of sPLA2 were enhanced by about 20-fold by 0.5 ng/ml IL-1beta or by 50 ng/ml of TNFalpha. Coaddition of both cytokines resulted in synergistic 150-fold increase in the release of sPLA2 implying the existence of two paths of induction. IL-1beta and TNFalpha markedly enhanced the transcription of sPLA2 mRNA. Kinetic study showed that IL-1/TNF initiated sPLA2 release after 12 h, reaching maximum at 48 h. IL-1alpha was a weak stimulator of sPLA2 release, whereas IL-6, IL-8, IGF, IFN-gamma, growth hormone, insulin and GM-CSF were not stimulatory. Peptide growth hormones TGFbeta, PDGF-BB, EGF and bFGF markedly inhibited the extracellular release of sPLA2. TGFbeta and PDGF-BB significantly reduced the level of sPLA2 mRNA, thus acting upon transcription whereas EGF and bFGF were not inhibitory, acting rather upon the translational or posttranslational steps. IL-1/TNF and growth factors had no significant effect on cPLA2 mRNA expression. Cox-2 mRNA expression was markedly enhanced by IL-1/TNF and suppressed by all growth factors tested. Cytokines enhanced the extracellular release of PGE2 and further enhancement was induced by growth factors with the exception of TGFbeta. Cycloheximide abolished completely the release of sPLA2 and markedly reduced the release of PGE2 from cytokine-stimulated FRCO, regardless of whether growth factors were present or not. NS-398, a specific inhibitor of Cox-2 abolished almost completely the release of PGE2 from cytokine-stimulated cells, regardless of the presence of growth factors. Thus, different signalling mechanisms are involved in the impact of growth factors on mRNA expression of sPLA2, cPLA2 and Cox-2. The differences between the impact on FRCO sPLA2 and that reported in other cells, imply that endogenous control of arachidonic acid cascade is cell-specific.

The effect of chemotherapeutic agents on chemotaxis and random migration of human leukocytes.

Chemotherapeutic agents (CTAs) used for treatment of neoplastic and other diseases may influence defense mechanisms of the patient, altering various humoral and cellular immunologic functions. Herein we report the influence of 16 CTAs on random migration and chemotaxis of human polymorphonuclear cells (PMNCs), using two methods, under-agarose migration and double-filter Boyden chambers with 51Cr-PMNCs. Random migration was inhibited by vinblastine only (P less than .01). BCNU and daunorubicin inhibited random migration only when used in high concentrations. In under-agarose migration, only BCNU and vinblastine inhibited chemotaxis (P less than .01) in therapeutic concentrations. Inhibition was also observed when higher concentrations of vincristine were tested. In the Boyden method, marked inhibition of chemotaxis (P less than .01) was caused by BCNU, vinblastine, vincristine, daunorubicin, and doxorubicin. Inhibition of chemotaxis could not be reversed by washing the cells after preincubation. CTAs per se did not have chemoattractant activity. This study shows that some chemotherapeutic agents inhibit random and directed migration of human PMNCs. It also supports the evidence that Boyden chamber method may detect chemotactic abnormalities that escape recognition by the under-agarose migration method. Suppression of locomotion of PMNCs should be taken into consideration in patients treated with CTAs.

Plasma cell neoplasia with osteosclerotic lesions. A study of five cases and a review of the literature.

Sixty-eight patients with plasmacytic neoplasia and osteosclerotic lesions were analyzed. Men predominated in this series. Mean age was 55.3 years and 26 patients were younger than 51 years at diagnosis. Early onset of disease was statistically different from multiple myeloma in general. Thirty patients had peripheral polyneuropathy and often neurological manifestations preceded other symptoms. Skeletal pain was less common, whereas hepatomegaly, splenomegaly, and lymphadenopathy were more common than in myeloma in general. Incidence of azotemia, hypercalcemia, high ESR, and anemia was lower than in myeloma. In one fourth of the patients, the number of skeletal lesions did not exceed three. Mean survival was less than 20 months from first symptom and 12 months from diagnosis. Mortality was related sometimes to polyneuropathy. Thus, in several aspects, plasmacytic neoplasia with osteosclerotic lesions is different from the classical multiple myeloma.

Treatment of plasma cell myeloma with cytotoxic agents.

Because cross-resistance between alkylating agents has not been observed, we attempt in a prospective trial to determine the advantages, if any, in administering three alkylating agents sequentially, alternately, or concurrently. A patient with myeloma, showing progressive shortening of M-protein doubling time from 98 to 15 days, developed an acute terminal phase, characterized by fever and pancytopenia. A similar acute terminal phase was observed in 17 of 50 deaths from myeloma. Since alkylating agents are only effective in controlling the chronic phase of myeloma, future improvements will require the discovery of agents that delay, prevent, or are effective in the treatment of the acute phase. Forty-five patients with kappa- and 36 with lambda-light-chain disease showed no differences in frequency of amyloidosis, renal failure, response to treatment, or survival after treatment with alkylating agents.

Multiple myeloma with discordant M components in the serum and CSF.

A patient with multiple myeloma was initially seen with Bence Jones-type kappa proteinemia and intermittent Bence Jones proteinuria. In the late stage of the disease, involvement of the CNS was observed, and abnormal plasma cells were found in the CSF. Chromosomal analysis of these plasma cells showed an accessory chromosome in the A2 group and an abnormal chromosome in the D13 group. In addition to Bence Jones-type kappa protein similar to that in the serum, the CSF contained IgA-kappa M component. Immunoquantitation detected 250 mg/dL of IgA in the CSF and only 33 mg/dL in the serum. T our knowledge, such discordance of M components has never been described before.

IgD multiple myeloma. Review of 133 cases.

One hundred thirty-three patients had IgD myeloma. The IgD comprises 0.8% of M-components in general and 2.1% of myelomas in particular. Males predominate and 65% of the patients are younger than 60 years at the diagnosis. More than half of the patients have lymphadenopathy, hepatomegaly, or splenomegaly. Extraosseous spread and amyloidosis are frequent. Severe anemia and azotemia are common. Total serum protein and IgD M-component levels are usually not high. LAMBDA-type light chains are found in 90% of IgD M-components. Bence Jones proteinimia is frequent and Bence Jones proteinuria appears in almost all patients. Mean survival is 13.7 months from diagnosis. The IgD is different from IgG and IgA myeloma, indicating that the clinical picture and course of multiple cyeloma may be related to the class and type of M-component.

Hyperviscosity syndrome in a patient with acquired immunodeficiency syndrome.

The hyperviscosity syndrome is most commonly seen in association with monoclonal gammopathies and has only rarely been described in association with polyclonal hypergammaglobulinemia. We have recently seen a patient with known acquired immunodeficiency syndrome who presented with the hyperviscosity syndrome in the setting of polyclonal hypergammaglobulinemia. To our knowledge, this is the first reported case of a patient with the acquired immunodeficiency syndrome and the hyperviscosity syndrome. The case is presented and the pathogenesis and implications of this diagnosis are discussed.

Interleukin-1 alpha stimulates the release of prostaglandin E2 and phospholipase A2 from fetal rat calvarial cells in vitro: relationship to bone nodule formation.

We have shown previously that interleukin-1 (IL-1) has biphasic effects on the formation of bone nodules in long-term cultures of fetal rat calvarial (RC) cells (Ellies and Aubin, Cytokine 2:430-437, 1990). To determine the role of arachidonic acid metabolism in this process, we have examined the release of prostaglandin E2 (PGE2) and phospholipase A2 (PLA2) from RC cells under conditions that allowed concomitant analysis of the formation of bone nodules. Recombinant human IL-1 alpha (rhIL-1 alpha) stimulated PGE2 and PLA2 release in a time- and dose-dependent manner. PGE2 release was highest in preconfluent cultures (days 1-6) and was stimulated up to 8.5-fold in response to 50 U/ml of rhIL-1 alpha. In contrast, extracellular PLA2 activity was maximal in postconfluent cultures, with 50 U/ml of rhIL-1 alpha causing a 20-fold increase by day 15. PLA2 release by RC cells was not significantly affected by PGE2, the glucocorticoid dexamethasone, or the cyclooxygenase inhibitor indomethacin. Indomethacin partially blocked the inhibition of bone nodule formation caused by rhIL-1 alpha, and exogenous PGE2 reversed this effect. Addition of group I PLA2 from Naja naja venom to RC cells had no effect on bone nodule development; however, group II PLA2 from Crotalus adamanteus venom inhibited the formation of bone nodules in a dose range similar to that induced by rhIL-1 alpha. These results indicate that PGE2 release does not have a direct temporal correlation with increases in PLA2 activity. In addition, the data show that only part of the inhibition of bone formation seen with rhIL-1 alpha is mediated by PGE2 and suggest that extracellular PLA2 also accounts for part of the inhibition.

Induction of circulating phospholipase A2 activity by intravenous infusion of endotoxin in patients with neoplasia.

The purpose of this study was to evaluate the impact of repeated intravenous infusions of endotoxin (EN) in patients with cancer on the systemic release of extracellular proinflammatory phospholipase A2 (PLA2) and its relationship to the release of tumor necrosis factor (TNF) and interleukin-6 (IL-6). Six patients received 15 infusion of EN isolated from Salmonella abortus equi at a dose of 4 ng/kg. Marked increase in the activity of circulating PLA2 was noted within 3 h after the first EN infusion and reached a maximal level of 20.4-fold greater than baseline 24 h after infusion. In five patients challenged with EN 2 weeks later, PLA2 reached peak levels 15.5-fold greater than baseline. In two patients who received three sequential daily infusions, the incremental increase in PLA2 activity after the second and third challenge reached maximum levels 6 h after EN infusion. PLA2 response followed those of TNF and IL-6 but was quantitatively different. Whereas maximal levels of TNF and IL-6 declined substantially after repeat EN challenges, no such decline occurred in PLA2 activity. Since, in the clinical setting of gram-negative sepsis, there is recurrent increase in circulating EN, our study approximates this clinical situation and shows that extracellular release of PLA2 follows temporally that of proximal cytokines such as TNF and IL-6. These cytokines may be related to PLA2 release and sustained high activity in the systemic circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Inflammatory effect of intradermal administration of soluble phospholipase A2 in rabbits.

Extracellular phospholipase A2 (PLA2) has been found in association with inflamed sites in experimental animals and in humans. The tissue effects of soluble PLA2 have not been defined. We studied the development of inflammatory changes in rabbit skin subsequent to intradermal injection of active and inactivated venom and pancreatic PLA2, over a broad concentration range. PLA2, at concentrations encountered in human disease, caused acute inflammatory changes characterized grossly by erythema and induration, and histologically by inflammatory cell infiltration, vascular and tissue damage, and abscess formation. Extracellular PLA2 may be considered as one of the pathogenic factors in inflammatory reaction.

Lymphadenopathy associated with dysgammaglobulinemia.

Conditions in which lymphadenopathy is associated with dysgammaglobulinemia may be divided into two groups: those in which etiologic factors and pathogenesis are well established, and those which are still a medical dilemma. Only a few belong to the former group: infections, immunizations, and drug-induced conditions being the best examples. Unfortunately, the great majority belong to the latter group. Interestingly enough, many conditions with lymphadenopathy and dysgammaglobulinemia share similar histologic features, such as infiltration with lymphocytes, immunoblasts, plasma cells, and histiocytes. This pleomorphic infiltration may appear together with prominent vascular proliferation. In animal experiments, angiogenesis was induced by administration of immunocompetent lymphocytes into the skin of unimmunized, irradiated mice. Therefore such lymphocyte-induced angiogenesis may be a manifestation of the graft-versus-host reaction. Recent developments in immunology, such as the discovery of many membranous markers and receptors on the lymphocyte membrane, the study of cytoplasmic structure and synthetic products, detection of enzymatic aberrations and chromosomal abnormalities, and refinement in histochemical techniques, have led to attempt to reclassify lymphoplasmacytic and leukemic disorders. Indeed, several classifications coming from different coutries and from various centers in the same country have been proposed, leading to a typical "Tower of Babel" phenomenon. It is obvious that more knowledge of etiologic factors and pathogenetic mechanisms is necessary to classify, cure, and eventually prevent the diseases described in this paper.

Plasma cell neoplasia with peripheral polyneuropathy. A study of five cases and a review of the literature.

Peripheral polyneuropathy (PPN) is a rare complication of plasma cell neoplasia (PCN), occurring in less than one percent of the patients. Fifty-four such patients (including our 5) were reviewed. There were 42 men (78%) and 12 women (22%) aged 28 to 72 years. Forty-nine percent of patients were younger than 51 years at the time of diagnosis. The initial complaints were different from those observed in multiple myeloma in general, and were related to polyneuropathy in 80% of the patients. PPN was usually of a mixed sensory-motor type and most often involved all four extremities. Skeletal pain was less common than in myeloma in general, occurring initially in 15% and at diagnosis in 45% of the patients. In 21 patients, reversibility of neuropathy was observed. These patients were compared to those with irreversible neuropathy and found to be relatively younger and more aggressively treated with irradiation and modern chemotherapy. Elevated sedimentation rate was uncommon. Less than half of the patients had anemia, and six patients, all with osteosclerotic lesions, had polycythemia. Azotemia was detected in 44% of the cases. No hypercalcemia was observed in 21 examined patients. M components were usually of IgG class, and when the light chains of M components were examined they were invariably of lambda type. Often the level of M component was below 2.0 g/dl. In all patients the bone marrow was infiltrated with immature, abnormal-looking plasma cells, but the infiltrate was often limited to one or a few foci. Solitary plasmacytoma was observed in 14 patients. No anemia, hypercalcemia or azotemia was recorded in this group. Eight patients had serum M components. Bone marrow aspirate was usually normal. In seven patients definite reversibility of PPN was observed after irradiation of plasmacytoma. Twelve patients presented with osteosclerotic lesions (22%), 18 with both osteosclerotic and osteolytic lesions (33%) and 13 with osteolytic lesions. Forty-two percent of the patients had less than three visible lesions in the skeleton. Eleven patients had either osteoporosis or radiologically normal skeleton. The mean survival from the first symptom was about 28 months and from the diagnosis 20 months. The five-year survival was 21% and 20%, respectively. These observations highlight the differences between PCN with PPN and multiple myeloma without PPN.

B-cell neoplasms with homogeneous cold-reacting antibodies (cold agglutinins).

Among 78 patients with persistent cold agglutinins, 31 had lymphoma, 13 had macroglobulinemia of Waldenstrom, six had chronic lymphocytic leukemia and 28 had chronic cold agglutinin disease. The average age was over 60 years. Patients wit chronic cold agglutinin disease had more hemolytic crises, bleeding and Raynaud's phenomena, and less frequently lymphadenopathy or hepatosplenomegaly. The frequency of anemia, positive Coombs test results, cryoglobulinemia and Bence Jones proteinuria was similar in the various groups. Survival time from diagnosis was on average two years in lymphoma, two and a half years in Waldenstrom's macroglobulinemia, more than six years in chronic lymphocytic leukemia and more than five years in chronic cold agglutinin disease. Anti-I were common in chronic cold agglutinin disease (74 percent) and rare in other groups (32 to 33 percent). Anti-I and other cold agglutinins were rare in chronic cold agglutinin disease and common in lymphoma and Waldenstrom's macroglobulinemia. In chronic cold agglutinin disease, and in Waldenstrom's macroglobulinemia, cold agglutinins usually had K light chains--92 percent and 71 percent, respectively--whereas in lymphoma, 71 percent of cold agglutinins had lambda light chains. The type of light chains related to the specifically of cold agglutinins: 58 percent of IgM/K were anti-I, 75 percent of IgM/lambda had other specificities. Cold agglutinins were cytotoxic to autologous and allogeneic cells were killed implying that the former may be precoated in vivo with the antibodies. In conclusion, conditions with persistent cold agglutinins are a spectrum that varies from "benign" autoimmune-like chronic cold agglutinin disease to malignant lymphoma. Marked differences in the light chain type of cold agglutinins, specificity toward membranous antigens and severity of clinical manifestations were noted in benign and malignant varieties.

Multiple myeloma (light chain disease) with rheumatoid-like amyloid arthropathy and mu-heavy chain fragment in the serum.

A 52 year old man presented with multiple myeloma and widespread amyloidosis involving joints, bursae- carpal tunnels, lymph nodes and subcutaneous tissue. Osteolytic bone lesions and pathologic fracture of the neck of the left femur were found. Bone marrow was infiltrated with both plasmacytes and lymphocytes. The majority of plasma cells contained large cytoplasmic vacuoles. Free kappa II type light chains and mu-heavy chain fragment were detected in the serum, and kappa II type Bence Jones protein was found in the urine. The molecular weight of the mu-heavy chain fragment was found to be approximately 50,000 daltons. An immunofluorescence study, using the double labelling technic, showed that the majority of plasmacytes in bone marrow contained both mu and kappa antigenic determinants in the cytoplasm. A review of the 12 previously described patients with mu-heavy chain fragment in the serum showed a variable clinical picture, thus their natural history and therapeutic response are difficult to evaluate at the present time. It seems that mu-heavy chain fragment can be found in a variety of clinical conditions and that mu-heavy chain disease cannot yet be accepted as a separate clinical entity.

Extracellular phospholipase A2 secretion is a common effector pathway of interleukin-1 and tumour necrosis factor action.

Inflammatory processes are characterized by increased levels of extracellular phospholipase A2 (PLA2) and cytokines such as interleukin 1 (IL-1) and tumour necrosis factor (TNF). IL-1, TNF and PLA2 share a number of proinflammatory, arthritogenic effects. The sequential induction, first of the cytokines followed by PLA2, suggests that these cytokines may regulate synthesis and secretion of PLA2. To test this postulate, foetal rat calvarial bone-forming cells (FRCC) were treated with recombinant human IL-1 and TNF and extracellular PLA2 release was quantitated. Both IL-1 and TNF induced the de novo synthesis of PLA2 in a concentration-dependent manner. Continuous exposure of FRCC in primary culture to IL-1 (50 units/ml) over 15 days resulted in as much as 100-fold increase in PLA2 secretion. IL-1 (50 units/ml) added to post-confluent cultures for a 48-h pulse increased PLA2 activity 9.4-fold. The combination of IL-1 (50 units/ml) and TNF (500 units/ml) was synergistic with an observed increase in extracellular PLA2 secretion of 146-fold following a 48-h pulse. Interleukin-6, alone or in combination with IL-1 or TNF, did not further enhance PLA2 synthesis of secretion. Cytokine-induced synthesis of PLA2 was inhibited 80% by 10 microM cycloheximide but not by dexamethasone over the range of 10(-6) to 10(-8) M. FRCC-derived PLA2 was neutral-active with a pH optimum of 6-7.5 and was calcium-dependent with optimal activity in the presence of 2-7 mM calcium. It had absolute 2-acyl specificity using micellar phosphatidylcholine.(ABSTRACT TRUNCATED AT 250 WORDS)