Immune responses to mouse neuroblastoma C1300. II. Cell-mediated kinetics and specificity studies

A 51Cr microcytotoxicity assay was used to study the kinetics of lymph-node- and spleen-cell-mediated cytotoxicity of A/JAX hosts following a single inoculum of the in vivo grown syngeneic neuroblastoma C1300. Lymph node cells (LNCs) demonstrated cytotoxicity which peaked at day 9, decreased as the tumor approached the 0.5-gram weight and increased again as the tumors grew. The increase in cytotoxicity following the depressed state was significantly greater than the initial peak, particularly in those mice bearing large tumors. Three groups of A/JAX mice were evaluated: mice receiving tumor cells alone; mice that were either thymectomized or splenectomized prior to inoculation, and mice that rejected the tumor. The C57Bl/6 served as an allogeneic comparison. Significant cytotoxicity was detected earlier with allogeneic LNCs than with spleen cells. Thymectomy and splenectomy elicited syngeneic LNC immune responses below or equal to the level found in nonimmune A/JAX hosts.