Differences in the sensitivities of murine metastatic lymphoma/lymphosarcoma variants to macrophage-mediated cytolysis and/or cytostasis.

A metastasizing animal tumor model for large cell lymphoma or lymphosarcoma has been established by sequential selection in vivo of the RAW117 parental cell line in BALB/c mice for enhanced colonization of liver or lung and in vitro for lack of binding to immobilized lectins. The parental RAW117 and selected sublines and clones derived from these were compared for their sensitivities in vitro to polyinosinic:polycytidylic acid-activated syngeneic macrophages in cytolysis and cytostasis assays. Activated but not unactivated macrophages had differing effects on RAW117 sublines and clones. The least metastatic (parental) cell line was the most sensitive to activated macrophage-mediated cytolysis and cytostasis, while the most metastatic subline was the least sensitive in these assays. Intermediate metastatic sublines or cones were usually less sensitive in one or both of the assays. These antitumor activities were negligible at 24 hr in the continuous presence of polyinosinic:polycytidylic acid but were clearly apparent by 48 to 72 hr. The results suggest that differential sensitivity to host macrophage surveillance mechanisms can occur in malignant cell subpopulations.