Specific receptor binding of staphylococcal enterotoxins by murine splenic lymphocytes.
We describe a reliable assay to measure the specific binding of 125I-labeled staphylococcal enterotoxin A (SEA) by murine spleen cells. Toxin binding by lymphocytes was specific in that it was inhibited by unlabeled SEA but not by unrelated proteins. The biological activity of SEA (T-lymphocyte mitogenesis) correlated with toxin binding to splenic lymphocytes. In the presence of high concentrations of [125I]SEA, specific binding increased rapidly and approached saturation after 2 h. Toxin binding was sensitive to temperature and pH and was directly proportional to the concentration of spleen cells in the incubation mixture. We estimated that there was a single class of toxin-binding sites, which had an apparent equilibrium dissociation constant (Kd) of 8 x 10(-7) M and numbered 3,600 sites per cell. SEA and the antigenically distinct compounds staphylococcal enterotoxins B and E in excess competitively inhibited binding of [125I]SEA to mouse spleen cells. Our data suggest a common class of binding sites for the three staphylococcal enterotoxins.
D000818:Animals; D004768:Enterotoxins / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D006162:Guanylate Cyclase; D008214:Lymphocytes / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008934:Mitogens; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; D011971:Receptors, Immunologic / Q000378:metabolism*; D018000:Receptors, Peptide; D013154:Spleen / Q000166:cytology
D004768:Enterotoxins; D008934:Mitogens; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; C019368:enterotoxin D, Staphylococcal; C026066:enterotoxin A, Staphylococcal; C031818:enterotoxin B, staphylococcal; D006162:Guanylate Cyclase; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled