Reconstitution of the intermediate-affinity interleukin-2 receptor by cell fusion.
Although IL-2 receptor beta chain (IL-2R beta) expressed in various lymphoid cell lines binds IL-2 with an intermediate affinity, IL-2R beta expressed in fibroblasts is unable to bind IL-2, suggesting that IL-2R beta is on its own not sufficient for generating the intermediate-affinity receptor and that lymphoid-specific regulatory control may be operated to allow IL-2R beta to bind IL-2. In the present study, we observed that human IL-2R beta expressed in a mouse myeloma X63-Ag8.653 (X63) by cDNA transfection did not bind IL-2, while the same IL-2R beta expressed in an IL-6-dependent mouse B cell hybridoma F12-28, which was obtained by cell fusion between X63 and lipopolysaccharide (LPS)-induced lymphoblasts, bound IL-2 with the intermediate affinity. Interestingly, when the human IL-2R beta cDNA-transfected X63 clone, which by itself manifests no IL-2 binding, was fused with LPS-induced lymphoblasts, the resultant hybridomas manifested intermediate-affinity IL-2 binding. The IL-2 binding was specifically inhibited by addition of antihuman IL-2R beta mAb (Mik-beta 1) but not by mAb against mouse IL-2R subunits, indicating that human IL-2R beta was responsible for the IL-2 binding, i.e. non-functional human IL-2R beta in X63 was converted to competent IL-2R beta by complementation with a mouse spleen cell-derived factor(s) through the cell fusion. Cross-linking experiments with [125I]IL-2 revealed the presence of a 61 kDa protein other than IL-2R beta in cells expressing the intermediate-affinity IL-2R.(ABSTRACT TRUNCATED AT 250 WORDS)
Kuida
K
K
Department of Immunology, Tokyo Metropolitan Institute of Medical Science, Japan.
Tanaka
T
T
Kitamura
F
F
Toyama-Sorimachi
N
N
Miyasaka
M
M
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001402:B-Lymphocytes / Q000378:metabolism; D002459:Cell Fusion; D006801:Humans; D006825:Hybridomas / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism*; D008213:Lymphocyte Activation; D051379:Mice; D008969:Molecular Sequence Data; D009101:Multiple Myeloma; D011485:Protein Binding; D015375:Receptors, Interleukin-2 / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011993:Recombinant Fusion Proteins