Abstract
Spleen cells collected from DBA/2 (H‐2~d~) mice inoculated with the polycythemic variant of Friend‐Leukemia Virus Complex (FLV‐P) were tested for T‐dependent immune functions, such as the in vitro generation of cytotoxic T lymphocytes (CTL) and of non‐specific T suppressor lymphocytes (STL). CTL were generated against H‐2~b~ splenocytes, and STL were obtained following a 5‐day lymphocyte culture without stimulator cells. A progressive and severe impairment of the generation of both CLT and STL was found from 2 weeks onward after infection, being almost totally abolished 3–4 weeks after virus challenge. Suppressor cells (SC) capable of inhibiting CTL generation was detected in FLV‐P bearing mice. Suppressor activity was unaffected by anti‐Thy 1.2 serum and complement but was removed following iron‐magnet depletion or passage through nylon‐wool column. Moreover complete recovery of the competence of CTL generation was attained when FLV‐P infected splenocytes were passed through nylon‐wool column. It is concluded that FLV‐P infection depresses T‐dependent cytotoxic and suppressor responses in mice, by the appearance of non‐T adherent phagocytic cells, capable of impairing CTL generation in vitro.