The 0 Antigenicity of Lymphoid Organs of Mice Bearing the Ehrlich Ascites Tumor1

Murine lymph node and thymus cells were tested for their sensitivity to the cytotoxic effect of 0 antibodies at various intervals after i.p. implantation of the Ehrlich ascites tumor. Within 16 days after tumor inoculation, both thymus and lymph node cells of RIII mice became almost completely refractory to 0-AKR antibodies. In C57BL mice, thymus cells lost their sensitivity to 0-C3H antibodies within 15 days after tumor implantation, while lymph node cells retained their sensitivity to 0 antibodies even after pro longed periods of tumor growth. Thymus cells of Ehrlich ascites tumor-bearing (RIII X C57BL) Ft hybrid mice lost their sensitivity simultaneously to 0-AKR and 0-C3H anti bodies, while lymph node cells of these hybrids showed no change in their sensitivity to 0 antibodies. The disappearance of cells sensitive to the cytotoxic effect of 0 antibodies from lymph nodes of tumor-bearing RIII mice seems to indicate that tumor growth may lead to depletion of thymus-dependent lymphocytes.