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Platelet Activating Factor Increases Expression of Complement Receptors on Human Neutrophils
Author(s) -
Shalit Meir,
Von Allmen Carolyn,
Atkins Paul C.,
Zweiman Burton
Publication year - 1988
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.44.3.212
Subject(s) - biology , platelet , receptor , microbiology and biotechnology , platelet activating factor , complement (music) , immunology , complement system , factor h , complement receptor , immune system , biochemistry , gene , phenotype , complementation
The phospholipid inflammatory mediator platelet activating factor (PAF) has been shown to stimulate certain functions of polymorphonuclear leukocytes (PMN). However, the effect of PAF on surface complement receptors of PMN has not been described. Using monoclonal antibodies and flow cytometry, we have assessed the effects of PAF on surface expression of membrane receptors for C3bi (CR3) and C3b (CR1) in human PMN. PAF (optimal concentration of 1 × 10 ‐8 M) increased CR3 190% and CR1 174% compared with unstimulated cells at 37°, while the PAF analogue lyso‐PAF had no stimulatory effect. Both CR3 and CR1 responses to PAF reached maximum levels at 15‐30 min. PAF effects were comparable to peak effects induced by LTB 4 but less than induced by FMLP. A PAF receptor antagonist, SRI 63‐441, blocked the increased complement receptor expression in a dose‐dependent manner with maximal inhibition of 80‐95% at 5 × 10 ‐6 M. Extracellular calcium had no effect on CR1 expression but slightly enhanced and EGTA partially inhibited the PAF‐induced increase in CR3 expression. Simultaneous incubation with PAF and LTB 4 enhanced CR3 and CR1 expression more than either agent alone. These findings indicate that PAF, alone and in combination with LTB 4 , can induce altered expression of complement receptors on the surface of PMN. This effect may enhance adhesion and phagocytosis by PMN at inflammatory reaction sites.