Direct cytotoxicity against chicken erythrocytes in mice. I. Fundamental nature of T cell-mediated cytotoxicity

Immune responses were examined after immunization with chicken erythrocytes (CRBC) in mice. Cytotoxicity of spleen cells was assessed by the release of ⁵¹Cr from labelled cells. (1) At early stages (day 4-7) after primary intraperitoneal immunization, direct cytotoxicity of spleen cells was raised efficiently in C57BL/6 and AKR mice, but not in C3H/He, SL and DDD mice. Delayed hypersensitivity and antibody production were raised to almost the same extent in all the strains at such periods. (2) Effector cells in direct cytotoxicity were θ-positive and IgG-positive, and glass-nonadherent and Nylon wool column-adherent. Effector cells in antibody-dependent cell-mediated cytotoxicity in the presence of antibody to CRBC were elmininated by treatment with anti-IgG serum but not by treatment with anti-θ serum. (3) Cytotoxicity and antibody production were raised efficiently after intraperitoneal or intravenous immunization, but not after footpad immunization. On the other hand, delayed hypersensitivity developed most efficiently after footpad immunization.