Heterogeneity in interleukin (IL)-1 receptors expressed on human B cell lines. Differences in the molecular properties of IL-1 alpha and IL-1 beta binding sites.
IL-1 alpha and IL-1 beta although distantly related at the primary sequence level, bind to the same Mr 80,000 IL-1 receptor on various cell types. Several lines of evidence indicate, however, that the IL-1 receptor on B cells and T cells differ. By binding experiments with 125I-IL-1, marked heterogeneity in IL-1 receptor binding was observed in 13 of 24 B cell lines studied. This was classified into three categories: (I) in nine cell lines, 125I-IL-1 alpha binding revealed high (kD = 10(-10) M) and low affinity (kD = 10(-8) M) IL-1 alpha receptors, whereas 125I-IL-1 beta binding showed one class only with intermediate affinity (kD = 10(-9) M); (II) in three cell lines selective binding with 125I-IL-1 beta was observed; (III) in one cell line only, 125IL-1 alpha and 125I-IL-1 beta bind to a single class of IL-1 receptors as has been described for most cell types. Cross-linking with 125I-IL-1 alpha or 125I-IL-1 beta demonstrated their specific binding to Mr 80,000 and to Mr 68,000 in cell lines in categories I and III, whereas for those in category II, binding to the IL-1 receptor was confined to 125I-IL-1 beta. The expression of two subsets of IL-1 alpha receptors but only one class of IL-1 beta receptors was further confirmed in kinetic studies. Internalization at 37 degrees C demonstrated that only 19% of IL-1 beta was internalized and that binding with IL-1 alpha was entirely cell surface. Flow cytometry studies showed that IL-1 alpha and IL-1 beta do not influence B cell surface antigen expression, suggesting that the ability of IL-1 to influence B cell proliferation is not mediated via direct binding to the IL-1 receptor only.
Benjamin
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D
Saint Francis Research Institute, University of Oklahoma, Health Sciences Center, Oklahoma City 73190.
Wormsley
S
S
Dower
S K
SK
D015703:Antigens, CD / Q000235:genetics; D000954:Antigens, Surface / Q000235:genetics; D001402:B-Lymphocytes / Q000276:immunology; D002051:Burkitt Lymphoma; D002460:Cell Line; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000378:metabolism*; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000276:immunology*
D015703:Antigens, CD; D000954:Antigens, Surface; D007375:Interleukin-1; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins