Monoclonal antibody against human interleukin 2 (IL 2). I. Purification of IL 2 for the production of monoclonal antibodies.

Human interleukin 2 (IL 2) was produced under serum-free conditions by stimulating mononuclear cells with concanavalin A (Con A) in the presence of phorbol myristate acetate (PMA) and hydroxyurea. The IL 2 was partially purified by sequential chromatography by using phenyl-Sepharose, DEAE Sephacel, and AcA 54 gel filtration. This partially purified material was used to immunize BALB/c mice. After immunization with a total of 48,000 U (spec. act. approximately 10(5) units/mg protein), the spleen cells were adoptively transferred into x-irradiated syngeneic mice and the animals were boosted with another 12,000 U of IL 2. Four days later their spleen cells were hybridized with plasmacytoma cells. Supernatants of the hybridoma cultures were screened for their capacity to inhibit the IL 2-induced proliferation of the CT6 cell line. After expansion and cloning eight different lines were selected for ascitic antibody production. The monoclonal antibodies inhibited the proliferation of the IL 2-dependent cell line in response to either human crude or purified IL 2, as well as rat and mouse IL 2. However, these anti-IL 2 antibodies did not inhibit the proliferation of human T cell lines capable of producing IL 2. Monoclonal antibodies coupled to Sepharose 4B absorbed IL 2 crude culture supernatant, confirming that they react directly with IL 2. The absorbed IL 2 could, for the most part, be eluted by using sodium dodecyl sulfate, thus providing a means for further immunoaffinity purification of IL 2.