Identification of soluble Fc receptors in mouse serum and the conditioned medium of stimulated B cells.
We have evaluated the expression of surface Fc gamma 2b/gamma 1R by lipopolysaccharide (LPS)-activated murine spleen cells, the release of soluble Fc gamma 2b/gamma 1R by activated spleen cells, and the presence of circulating Fc gamma 2b/gamma 1R in mouse serum. LPS activation of murine spleen cells and a cloned B cell line, BCL-1 CW 13.20-3B3, resulted in a 5-10-fold increase in surface Fc gamma 2b/gamma 1R and the concominant appearance in the culture medium of a soluble molecule that is antigenically related to the Fc gamma 2b/gamma 1R. The increase in cell-associated and soluble Fc gamma 2b/gamma 1R after LPS activation is attributable primarily to B cells. Circulating Fc gamma 2b/gamma 1R was also detected in normal mouse serum at a concentration of 10(-9) to 10(-8) M. Levels of circulating Fc gamma 2b/gamma 1R increase with the age of the animals, and were low in adult germ-free mice and elevated in young mice with certain autoimmune diseases. The circulating Fc gamma 2b/gamma 1R bound to IgG-Sepharose, and was partially purified by affinity chromatography on 2.4G2 Fab-Sepharose. After radiolabeling and immunoprecipitation with rabbit anti-Fc gamma 2b/gamma 1R serum, one component of Mr 48,000, was detected.
D000818:Animals; D001402:B-Lymphocytes / Q000032:analysis*; D003470:Culture Media / Q000032:analysis; D005260:Female; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D011863:Radioimmunoassay / Q000379:methods; D011961:Receptors, Fc / Q000032:analysis*; D017452:Receptors, IgG; D013154:Spleen / Q000032:analysis / Q000187:drug effects
D003470:Culture Media; D008070:Lipopolysaccharides; D011961:Receptors, Fc; D017452:Receptors, IgG