Monoclonal antibodies to distinct functional epitopes of the murine IL-2 receptor

R. G. Ortega, R. J. Robb, E. M. Shevach, T. R. Malek

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Abstract

The properties of three distinct rat monoclonal antibodies designated 3C7, 7D4, and 2E4, to the murine interleukin (IL-2) receptor have been compared. 3C7 appears to define an epitope near or identical to the IL-2 binding site of the receptor because 3C7 inhibited the binding of radiolabeled IL-2 to CTL-L cells and because unlabeled IL-2 inhibited the binding of 3C7 to CTL-L cells. 7D4 and 2E4 had no effect on IL-2 binding. Competitive antibody binding studies confirmed that the epitope seen by 3C7 was distinct from the epitope(s) seen by 7D4 and 2E4. Sequential immunoprecipitation studies demonstrated that all three antibodies were reactive with the same molecular species and each precipitated identical components of 20,000-25,000 daltons, 50,000-60,000 daltons, and 100,000-120,000 daltons from the surface of CTL-L. FACS studies demonstrated a quantitatively identical cell distribution for the antigen defined by each antibody. They failed to stain >95% of resting lymphocytes but were strongly reactive with T blasts and substantially less reactive with B blasts. Each antibody inhibited IL-2 driven proliferation of HT2 or CTL-L cells. 3C7 and 7D4 were more potent inhibitors of proliferation than 2E4 and the combined use of 3C7 and 7D4 resulted in synergistic inhibition of proliferation. Collectively, the results support the hypothesis that these antibodies detect two distinct functional regions of the IL-2 receptor.

Original languageEnglish (US)
Pages (from-to)no. 2922
JournalFederation Proceedings
Volume43
Issue number7
StatePublished - Jan 1 1984

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ASJC Scopus subject areas

  • Medicine(all)

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