Allogeneic fibroblasts and endothelial cells support mitogen but not antigen responses of tetanus-responsive T-cell lines.

Recent studies suggest a role for endothelial cells (EC) and fibroblasts (FB) in performing certain accessory functions of monocytes in immune responses. We examined the ability of allogeneic adherent cells (AC), umbilical vein EC, and foreskin FB to support antigen and mitogen responses of tetanus toxoid-responsive human T-cell lines (TCTet). Syngeneic AC supported antigen and mitogen (phytohemagglutinin and pokeweed mitogen, PHA and PWM) responses of TCTet. Allogeneic AC, EC, and FB supported mitogen but not antigen responses of TCTet, in a dose-dependent manner. PHA-activated mononuclear cell supernates or EC or FB supernates could not replace accessory cells in mitogen responses. We provide further evidence that EC and FB can function as fully competent accessory cells, a function that may be of significance in in vivo initiation of immune responses.