Subpopulations of human T lymphocytes. II. Effect of thymopoietin, corticosteroids, and irradiation.

Lymphoid cells from normal SJL/J mice gave high proliferative responses but failed to develop cytotoxic activity to γ-irradiated cells from syngeneic transplantable reticulum cell sarcomas (X-RCS). In spite of a vigorous in vivo proliferative response to X-RCS, cytotoxic activity was never generated to detectable levels in vivo. After repeated injections of X-RCS, spleen and, to a lesser degree, lymph node cells acquired the ability to give moderate secondary cytotoxic responses in vitro upon co-culture with X-RCS. This immunity was T-cell mediated and specific for RCS although it did not distinguish between different transplantable RCS lines. SJL/J mice also developed resistance to RCS growth after injection of X-RCS, which showed a transient RCS-line-specific component. (SJL/J × C₅₇B1/6)F₁ mice showed 60% less RCS growth than did SJL/J mice, and their lymphoid cells gave slightly lower proliferative responses than did cells from SJL/J mice, whereas (SJL/J × BALB/c)F₁ mice showed little tumor growth, and their spleen cells proliferated only minimally to X-RCS. B10.S mice allowed moderate RCS growth. Cytotoxic activity was generated in co-cultures with X-RCS of immunized F₁ spleen cells even after a single immunization in vivo but not in cultures of normal F₁ cells with X-RCS.