The role of immunoglobulins in lymphocyte-mediated cell damage, in vitro. I. Comparison of the effects of target cell specific antibody and normal serum factors on cellular damage by immune and non-immune lymphocytes.

Rats were immunized by intraperitoneal injection of target cells (Chang cells). Five days after immunization antibody, lytic to Chang cells in the presence of complement, which separated in Peak I on Sephadex G-150 was detectable. At the same time antibody lytic to Chang cells in the presence of lymphoid cells from unimmunized animals and separating in Peak II on Sephadex G-150 was found. Both antibodies reached a maximum titre between 2 and 4 weeks after immunization. At that time the antibody dependent upon normal lymphoid effector cells was active at more than 1000 times the maximal dilution of complement dependent antibody activity. The Peak II antibody affected both im-immune and non-immune Black Hooded (BH) rat spleen cells in a similar way. Normal rat serum markedly enhanced target cell survival. This effect did not require heat labile components of complement. The enhancing capacity of immune serum appears to be greater than that of normal serum; the reason for this is discussed, but the problem is not resolved.