Heterogeneity of type-II interleukin-1 receptors. Heterogeneity of B-cell interleukin-1 binding created by dimerization of type-II interleukin-1 receptors.
The binding of IL-1 alpha and IL-1 beta to two human lymphoblastoid B-cell lines, Raji and RPMI 1788, was compared with binding to the murine T-cell line, EL4. Dramatic differences in IL-1 binding were observed. Both human B-cell lines bound much less IL-1 alpha than IL-1 beta, expressed 5-10 times more receptors per cell for IL-1 beta than did the EL4 cell line, and demonstrated a large difference in the ability of IL-1 alpha to compete with IL-1 beta for binding. The B-cell lines demonstrated a low number of high-affinity IL-1 alpha receptors and a large number of IL-1 alpha receptors with a much lower affinity. Inhibition studies demonstrated that only IL-1 beta could compete for the binding of radiolabeled IL-1 beta to the B-cell IL-1R. Furthermore, SDS-PAGE analyses of lysates of the B-cell lines that had been affinity cross-linked with 125I-IL-1 alpha revealed two bands corresponding to IL-1R structures of 60 and 110 kD. These results coupled with a nonequilibrium binding study suggested a dimerization of a common type-II IL-1R polypeptide, the dimer being responsible for the high-affinity IL-1 alpha-binding site of the B-cell lines.
Cronkhite
R I
RI
Department of Immunology, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado.
Lobick
J J
JJ
Plate
J M
JM
D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D001667:Binding, Competitive; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D051379:Mice; D017472:Receptors, Interleukin-1 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism; D014407:Tumor Cells, Cultured
D007375:Interleukin-1; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins