The biochemical and biological characterization of lymphocyte regulatory molecules. VI. Generation of a B cell hybridoma whose antibody product inhibits interleukin 2 activity.

In attempts to generate monoclonal antibodies with reactivity directed against the lymphokine Interleukin 2 (IL-2, T cell growth factor), spleen cells harvested from BALB/c mice previously immunized with rat IL-2 were fused with the BALB/c myeloma SP2. Several of the resultant hybrid cell lines secreted a product that significantly neutralized (greater than 50%) IL-2--dependent T cell proliferation. Several lines of evidence suggested that the inhibitory activity was associated with a monoclonal IgG antibody directed against IL-2 determinants. First, passage of cloned hybrid cell culture supernatants through a protein A-coupled Sepharose column yielded purified immunoglobulin G fractions that inhibited mouse, rat, and human IL-2 activity. Secondly, hybridoma-derived IgG, in concert with lyophilized Staphylococcus aureus, was capable of precipitating both "cold" and intrinsically labeled IL-2 activity. Finally, Sepharose conjugated with purified IgG fractions provided on extremely reactive IL-2 absorption matrix. These results suggest that monoclonal antibodies directed against IL-2 determinants may eventually provide new detection assays for IL-2 and allow affinity chromatography to be employed for the isolation of this lymphokine.