Fibroblast lysis by lymphocytes from normal persons and SLE patients on short-term cultures

Lymphocytes from thirty-six normal individuals of both sexes with ages ranging from 4-89 years were tested for their cytotoxic activity against short term cluters of fibroblasts from nine foetal umbilical cords and nine adult skin samples. Wide variability in the amount of fibroblast lysis was observed. Adult male lymphocytes caused significantly higher lytic activity than lymphocytes of adult females against both types of targets. Cell-mediated target cell reduction was not confined to allogeneic target cells. There was also killing of autochthonous cultured fibroblasts. Some individuals' sera inhibited the fibroblast lytic activity of their own lymphocytes. These cell-mediated reactions are directed against unknown antigenic specifications, probably not histocompatibility antigens, and give evidence of the problem of how to measure normal controls in the microcytotoxicity test in allogeneic human testing. Both autochthonous and allogeneic target cell lysis were also observed in SLE patients.