MONOCLONAL-ANTIBODIES AGAINST RECOMBINANT HUMAN GROWTH-HORMONE AS PROBES TO STUDY IMMUNE FUNCTION

Monoclonal antibodies were raised against human recombinant growth hor mone (rhGH) and those that did not cross-react with other human recomb inant proteins like prolactin (PRL), interleukin 2 (IL-2), insulin, or bovine pituitary growth hormone were selected, The selected hybridoma supernatants were studied for their ability to influence T lymphocyte proliferation when induced either by a mitogen, such as phytohemagglu tinin (PHA), or by alloantigen, All supernatants inhibited proliferati on, Three MAbs were then purified by several passages on antimouse IgG (or IgM)-agarose columns, and characterized, These MAbs recognized th ree different epitopes, as revealed by competition study, although the ir inhibitory effect on PHA-induced T cell proliferation was quite sim ilar, The data demonstrate that the MAbs were not cytolytic, that they did not interfere with the PHA binding to T cell membranes, and, as r evealed by FAGS analysis, did not bind to the membrane, Finally, these MAbs immunoprecipitated a 44-kDa molecule from PHA-activated T cell-c oncentrated supernatants. These data indicate that the MAbs recognized a soluble factor that plays a central role in T cell proliferation an d that is probably the immune growth hormone.