Effect of platelet-activating factor on monocyte activation and production of tumor necrosis factor.
The effect of platelet-activating factor (PAF) or human peripheral-blood-derived monocytes (PBM) was examined. The addition of PAF to monocyte cultures did not activate the cells to mediate cytotoxicity activity against 51Cr-labeled target cells. Furthermore, supernatants derived from the treated cultures were not cytotoxic. However, these supernatants contained tumor necrosis factor (TNF) when assayed by a sensitive radioimmunoassay. Further kinetic studies indicated that cytotoxic supernatant is detected at 2-4 h following PAF treatment but not overnight treatment, suggesting, perhaps, the presence of inhibitors interfering with the cytotoxic activity. Cells pretreated with PAF responded poorly to a second stimulation with phorbol myristate acetate whereas a secondary response was seen with cells pretreated with interferon-gamma. These results suggest that PAF is involved in regulating cytokine production by monocytes and thus plays a role in the immune response to foreign antigens.
Bonavida
B
B
Department of Microbiology and Immunology, University of California, UCLA School of Medicine.
Mencia-Huerta
J M
JM
Braquet
P
P
D002460:Cell Line; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000502:physiology*; D009000:Monocytes / Q000187:drug effects* / Q000502:physiology; D010972:Platelet Activating Factor / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D010972:Platelet Activating Factor; D014409:Tumor Necrosis Factor-alpha; D013755:Tetradecanoylphorbol Acetate