In Vivo Activity of a Nonspecific T Cell-Replacing Factor

Abstract
Nonspecific T cell-replacing factors prepared as supernatants from mixed lymphocyte cultures or concanavalin A-stimulated spleen cells are active in vivo if injected into nude mice at least 3 days before antigen. The supernatants appear to act by enhancing the weak IgM responses that occur in untreated nudes. Secondary responses and IgG antibody were not found.