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Glucocorticoid induced suppression of phagocytosis and altered lipid metabolism in murine resident peritoneal macrophage cultures
380
GLUCOCORTICOID INDUCED SUPPRESSION OF PHAGOCYTOSIS AND ALTERED LIPID METABOLISM IN MURINE RESIDENT PERITONEAL MACROPHAGE CULTURES. J. Becker, R.J. Grasso and J.S. Davis. Univ. So. Fla. Coll. Med., Tampa, Florida, U.S.A. Treatment of maerophages for 3 days with I ~M dexamethasone (DEX) inhibits the ingestion of heat-killed Saccharomyces cerevisiae. Glucocorticoids also induce phospholipase (PL) inhibitory proteins which suppress arachidonate (AA) release from phosphatidylcholine (PC). Thus, we explored whether the inhibition of PL suppresses phagocytosis and if DEX alters the phospholipid (PPL) content of the macrophages. Control and DEX treated cultures were exposed to bromophenacyl bromide, a specific PL inhibitor, and to nonspecific PL inhibitors quinacrine and tetracaine. The inhibitors suppressed phagocytosis in control and DEX treated cultures. To detect alterations in lipid content, cultures were labeled with 14C-AA and the percentages of the label associated wSth PPL and neutral lipids (NL) were determined. Before phagocytosis, the percentages of I4C-AA associated with PL versus NL were the same from control and DEX treated cells. However, after 15 min of phagocytosis, the control macrophages showed increased incorporation of label into NL with a corresponding decrease in PPL. This shift was associated with a decreased percentage of label in PC. In contrast, DEX treated cells showed little change after phagocytosis in the percentages of label present in PPL and NL. Hence, the ability of PL inhibitors to suppress yeast ingestion suggests that phagocytosis depends on functional PL activity. Since DEX treated cells showed little exchange of label from PPL to NL after yeast ingestion, the DEX induced suppression of phagocytosis may be associated with the inhibition of PL.
87
BENOXAPROFEN MEDIATED INDUCTION OF NON-SPECIFIC SUPPRESSOR ACTIVITY IN HUMANMONONUCLEAR LEUCOCYTES IN VITRO BY PRO-OXIDATIVE MECHANISMS. H. EFTYCHIS AND R. ANDERSON. Pathology I ~ , University of Pretoria, Pretoria, South Africa. We have previously reported the non-steroidal anti-inflammatory drug (NSAID) benoxaprofen (B x P) possesses pro-oxidative properties i . e . stimulates leucocyte membrane associated oxidative metabolism. In this study the relationship between the pro-oxidative properties of the drug and i t s immunosuppressive effects in v i t r o were investigated. Mononuclear leucocytes (MNL~ were obtained from normal adult volunteers and exposed to B x P at concentrations I0 -~ - I0-6Mo Lymphocyte transformation mediated by the mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A), induction of spontaneous and Con A-induced suppressor a c t i v i t y were assayed on MNL and MNL depleted of adherent c e l l s . Anti-oxidant effects of ascorbate or cysteine were also assessed. B x P stimulatory effects on MNL oxidative metabolism were confirmed by chemiluminescence, sulfhydryl oxidation and autoiodination. B x P at pro-oxidative concentrations inhibited lymphocyte transformations (=m10-5M) and induced non-specific suppressor a c t i v i t y in MNL. Inclusion of anti-oxidants and depletion of adherent cells from MNL eliminated these effects. B x P induces immunosuppression in v i t r o by an adherent cell-dependent pro-oxidative mechanism.
88
SYNERGISM OF 3-DEAZAADENOSINE (3-DAA) OF ANTIBODY-DEPENDENT PHAGOCYTOSIS
89
WITH
SOLUBLE
IMMUNE COMPLEXES
IN THE
INHIBITION
J.L. Medzihradsky The Wellcome Research Laboratories, Research Triangle Park, NC, U.S.A. It has been shown previously that modulation of phagocytosis by the S-adenosyl-L-homocysteine hydrolase inhibitor, 3-DAA, was dependent on the degree of target cell opsonization by antibody (J. Immunol. 133:946, 1984). We now present further evidence on the existence of a regulatory control by antigen-antibody complexes over the effects of 3-DAA. Soluble immune complexes have been known to inhibit antibody-dependent phagocytosis (AD~) in vitro. In an AD~ assay system based on 51CR-labeled chromium retention in phagocytized sheep erythrocytes by mouse resident peritoneal macrophages, soluble antigen-antibody complexes of ovalbumin (OVA)-anti-OVA antibodies and sera from autoimmune MRL/Mp-lpr/Ipr mice were tested in combination with 3-DAA. When present during the assay, 3-DAA acted synergistically with these biological materials in the inhibition of AD~. Using OVA-anti-OVA complexes, the effect was evident at high (i0 ~g/ml) anti-OVA antibody concentrations. The synergistic effect measured by the reduction of 50% inhibitory concentrations of 3-DAA correlated with auto-immune serum concentrations. Data indicate that this regulatory interaction may represent a mechanism by which 3-DAA can enhance the clearance of circulating immune complexes.
GLUCOCORTICOID INDUCED SUPPRESSION OF PHAGOCYTOSIS AND ALTERED LIPID METABOLISM IN MURINE RESIDENT PERITONEAL MACROPHAGE CULTURES. J. Becker, R.J. Grasso and J.S. Davis. Univ. So. Fla. Coll. Med., Tampa, Florida, U.S.A. Treatment of maerophages for 3 days with I ~M dexamethasone (DEX) inhibits the ingestion of heat-killed Saccharomyces cerevisiae. Glucocorticoids also induce phospholipase (PL) inhibitory proteins which suppress arachidonate (AA) release from phosphatidylcholine (PC). Thus, we explored whether the inhibition of PL suppresses phagocytosis and if DEX alters the phospholipid (PPL) content of the macrophages. Control and DEX treated cultures were exposed to bromophenacyl bromide, a specific PL inhibitor, and to nonspecific PL inhibitors quinacrine and tetracaine. The inhibitors suppressed phagocytosis in control and DEX treated cultures. To detect alterations in lipid content, cultures were labeled with 14C-AA and the percentages of the label associated wSth PPL and neutral lipids (NL) were determined. Before phagocytosis, the percentages of I4C-AA associated with PL versus NL were the same from control and DEX treated cells. However, after 15 min of phagocytosis, the control macrophages showed increased incorporation of label into NL with a corresponding decrease in PPL. This shift was associated with a decreased percentage of label in PC. In contrast, DEX treated cells showed little change after phagocytosis in the percentages of label present in PPL and NL. Hence, the ability of PL inhibitors to suppress yeast ingestion suggests that phagocytosis depends on functional PL activity. Since DEX treated cells showed little exchange of label from PPL to NL after yeast ingestion, the DEX induced suppression of phagocytosis may be associated with the inhibition of PL.
87
BENOXAPROFEN MEDIATED INDUCTION OF NON-SPECIFIC SUPPRESSOR ACTIVITY IN HUMANMONONUCLEAR LEUCOCYTES IN VITRO BY PRO-OXIDATIVE MECHANISMS. H. EFTYCHIS AND R. ANDERSON. Pathology I ~ , University of Pretoria, Pretoria, South Africa. We have previously reported the non-steroidal anti-inflammatory drug (NSAID) benoxaprofen (B x P) possesses pro-oxidative properties i . e . stimulates leucocyte membrane associated oxidative metabolism. In this study the relationship between the pro-oxidative properties of the drug and i t s immunosuppressive effects in v i t r o were investigated. Mononuclear leucocytes (MNL~ were obtained from normal adult volunteers and exposed to B x P at concentrations I0 -~ - I0-6Mo Lymphocyte transformation mediated by the mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A), induction of spontaneous and Con A-induced suppressor a c t i v i t y were assayed on MNL and MNL depleted of adherent c e l l s . Anti-oxidant effects of ascorbate or cysteine were also assessed. B x P stimulatory effects on MNL oxidative metabolism were confirmed by chemiluminescence, sulfhydryl oxidation and autoiodination. B x P at pro-oxidative concentrations inhibited lymphocyte transformations (=m10-5M) and induced non-specific suppressor a c t i v i t y in MNL. Inclusion of anti-oxidants and depletion of adherent cells from MNL eliminated these effects. B x P induces immunosuppression in v i t r o by an adherent cell-dependent pro-oxidative mechanism.
88
SYNERGISM OF 3-DEAZAADENOSINE (3-DAA) OF ANTIBODY-DEPENDENT PHAGOCYTOSIS
89
WITH
SOLUBLE
IMMUNE COMPLEXES
IN THE
INHIBITION
J.L. Medzihradsky The Wellcome Research Laboratories, Research Triangle Park, NC, U.S.A. It has been shown previously that modulation of phagocytosis by the S-adenosyl-L-homocysteine hydrolase inhibitor, 3-DAA, was dependent on the degree of target cell opsonization by antibody (J. Immunol. 133:946, 1984). We now present further evidence on the existence of a regulatory control by antigen-antibody complexes over the effects of 3-DAA. Soluble immune complexes have been known to inhibit antibody-dependent phagocytosis (AD~) in vitro. In an AD~ assay system based on 51CR-labeled chromium retention in phagocytized sheep erythrocytes by mouse resident peritoneal macrophages, soluble antigen-antibody complexes of ovalbumin (OVA)-anti-OVA antibodies and sera from autoimmune MRL/Mp-lpr/Ipr mice were tested in combination with 3-DAA. When present during the assay, 3-DAA acted synergistically with these biological materials in the inhibition of AD~. Using OVA-anti-OVA complexes, the effect was evident at high (i0 ~g/ml) anti-OVA antibody concentrations. The synergistic effect measured by the reduction of 50% inhibitory concentrations of 3-DAA correlated with auto-immune serum concentrations. Data indicate that this regulatory interaction may represent a mechanism by which 3-DAA can enhance the clearance of circulating immune complexes.