Distribution and survival of passively transferred lymphoblasts in normal and tumor‐bearing mice

Although most circulating lymphocytes are long-lived small lymphocytes, it is the recently-divided medium and large-sized lymphoblasts that most clearly migrate to sites of inflammation, and they do so without regard to immunologic commitment. The tumor-bearing state frequently suppresses macrophage accumulation at inflammatory sites but it is not known whether lymphocyte traffic is similarly affected. We addressed this issue using passively transferred radiolabelled lymphoblasts. Lymphoblasts readily entered s.c. fibrosarcomas transplanted to C57BL/6 mice. Large and small tumors acquired the same number of lymphoblasts per gram of tumor, indicating the absence of an anti-inflammatory reaction. However, the intra-tumoral survival of lymphoblasts was shorter in large than in small tumors. Shortened survival was noted also in spleen and whole body of animals bearing tumors. Shortened survival rather than impaired emigration may contribute to the increase in tumor:lymphocyte ratio observed with large tumors. The adverse effect of tumor bearing on lymphoblast survival may be limited to tumors which acquire a high percentage of passively transferred lymphocytes since intraperitoneal P-815 mastocytomas in DBA/2 mice acquired few labelled lymphoblasts and did not alter lymphoblast survival. These results are important for host resistance to tumor growth and therapeutically for the use of lymphocyte cytotoxic cells induced to proliferate in vitro.