Two distinct affinity binding sites for IL-1 on human cell lines.
We used two human cell lines, NK-like YT-C3 and an EBV-containing B cell line, 3B6, as models to study the receptor(s) for IL-1. Two distinct types of saturable binding sites were found on both cell lines at 37 degrees C. Between 1 pM and 100 pM of 125I-IL-1-alpha concentration, saturable binding sites were detected on the YT-C3 cells with a K of 4 x 10(-11) M. The K found for the IL-1-alpha binding sites on 3B6 cells was 7.5 x 10(-11) M. An additional binding curve was detected above 100 pM on YT-C3 cells with a K of 7 x 10(-9) M and on 3B6 cells with a K of 5 x 10(-9) M. Scatchard plot analysis revealed 600 sites/cell with high affinity binding and 7000 sites/cell with low affinity for YT-C3 cells and 300 sites/cell with high affinity binding and 6000 sites/cell with low affinity for 3B6 cells. At 37 degrees C, the internalization of 125I-labeled IL-1 occurred via both high and low affinity IL-1R on both YT-C3 and 3B6 cells, whereas the rates of internalization for high affinity binding sites on YT-C3 cells were predominant in comparison to that of low affinity binding sites. In chemical cross-linking studies of 125I-IL-1-alpha to 3B6 and YT-C3 cells, two protein bands were immunoprecipitated with Mr around 85 to 90 kDa leading to an estimation of the Mr of the IL-1R around 68 to 72 kDa. In similar experiments, the Mr found for the IL-1R expressed on the murine T cell line EL4 was slightly higher (around 80 kDa). Whether these distinct affinity binding sites are shared by a single molecule or by various chains remains to be elucidated.
Bensimon
C
C
UA1156 CNRS, Institut Gustave Roussy, Villejuif, France.
Wakasugi
N
N
Tagaya
Y
Y
Takakura
K
K
Yodoi
J
J
Tursz
T
T
Wakasugi
H
H
D000293:Adolescent; D000818:Animals; D001667:Binding, Competitive; D003432:Cross-Linking Reagents; D004705:Endocytosis; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism* / Q000502:physiology; D007457:Iodine Radioisotopes / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism; D011971:Receptors, Immunologic / Q000032:analysis* / Q000502:physiology; D017472:Receptors, Interleukin-1; D013696:Temperature; D013945:Thymoma / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000378:metabolism
D003432:Cross-Linking Reagents; D007375:Interleukin-1; D007457:Iodine Radioisotopes; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1