T-CELLS AS ANTIGEN-PRESENTING CELLS

Human T cells express major histocompatibility complex (MHC) class II antigens and adhesion molecules characteristic of antigen-presenting c ells (APCs), and recent in vitro and in vivo evidence supports an anti gen-presenting function for T cells. In this guise, T cells provide do wnregulatory signals for the immune response by inducing anergy in T c ells that have already been activated and cytotoxicity in resting T ce lls. Here, Werner Pichler and Tony Wyss-Coray suggest that this may re present art important negative mechanism for T-cell homeostasis.