The role of accessory cells and T cell-growth factor in induction of cytotoxic T lymphocytes against herpes simplex virus antigens.

The roles of accessory cells and T cell-growth factor (TCGF) in the in vivo induction of herpes simplex type 1 (HSV) specific cytotoxic lymphocytes (CTL) were evaluated. Spleen cells from animals infected with HSV 4-6 weeks previously were depleted of adherent cells by passage over Sephadex G10. Unlike intact cells, such depleted spleen cells failed to respond by producing H-2 restricted virus-specific CTL upon culture for 5 days with infectious HSV. The CTL response could be restored either by adding normal genetically compatible peritoneal cells as accessory cells or by the addition of TCGF. To obtain optimum restoration accessory cells needed to be added soon after culture initiation but with TCGF addition, partial restoration was evident when added as late as 72 hr after culture. TCGF also permitted intact spleen cells to respond to heat-inactivated virus. The results are interpreted to indicate that accessory cells are essentially required for the presentation of virus to specific helper cells with such cells responding by the production of TCGF. The results also indicate that certain forms of virus may trigger the response of CTL precursors but not the response of helper cells.