Immune response against vaccinia virus in rhesus monkeys: no evidence for primary MHC-restricted cytolytic T cells.

Rhesus monkeys were tested in vitro for their cellular immune response after infection with vaccinia virus, employing lymphocyte preparations from various lymphoid tissues. Although virus-infected target cells were lysed by lymphoid cells from immunized, but not from uninfected, rhesus monkeys, we could neither find evidence for MHC-restricted T cells nor for antibody-dependent cellular cytotoxicity. Kinetics of target cell lysis, the killing patterns of immune lymphocytes measured on syngeneic, allogeneic, and xenogeneic target cells, and the influence of protein A on cytotoxic activity in vitro suggest induction predominantly of natural killer cells in vivo which exhibit lytic activity on virus-infected target cells in vitro.