Autoantibodies produced spontaneously by young 1pr mice carry transforming growth factor beta and suppress cytotoxic T lymphocyte responses

Young MRL/MPJ-lpr (lpr) mice 8-12 wk old challenged with alloantigen had significantly lower specific cytolytic T lymphocyte (CTL) responses than control MRL/MPJ +/+ mice. Serum from lpr mice compared with serum from ++ or normal C3H mice powerfully suppressed CTL responses in mixed lymphocyte cultures (MLC); absorbing lpr serum on protein G, adding antibody against transforming growth factor beta (TGF-beta) to cultures or dissociating immunoglobulin G (IgG) and TGF-beta before additions to cultures prevented suppression. Apparently autoantibody, similar to IgG produced by normal mice in response to immunization, carries TGF-beta which suppresses CTL responses in vivo and in vitro.