Reversibility of the Immunodepression Due to Ehrlich Ascites Carcinoma

Earlier studies from our laboratory indicated that mice bearing Ehrlich ascites carcinoma cells (EAC) 2 produce far fewer plaque-forming cells (PFC) after immunization with sheep erythrocytes (SRBC) than do normal animals. The immunodepression develops shortly after a low dose of EAC, before wasting, and does not result from lymphocyte depletion of peripheral organs, as ascertained by cytometric and histologic studies (1, 2). The failure to produce PFC may be due to lymphocyte malfunction or to some other mechanism such as antigen processing in tumorbearing animals. In the present study we demonstrate that thymus- and bone marrow-derived lymphocytes, and spleen cells from tumor-bearing and normal donors, transferred to x-irradiated syngeneic mice, produce the same numbers of PFC to SRBC. Materials and Methods. Animals . C57BL inbred mice, 8 to 12 weeks old, were used. Tumor . Inocula of 10 7 cells of a half-diploid and half-tetraploid strain of EAC were injected intraperitoneally (i.p.) into prospective donors of thymus, bone marrow and spleen cells (3).