T-lymphocytes and macrophages in primary murine fibrosarcomas at different stages in their progression.

The relative contribution of lymphocytes, macrophages, and granulocytes to the cell content of primary 3-methyl-cholanthrene-induced murine fibrosarcomas was determined at different stages in their progression by differential cell analysis on enzyme-derived single-cell suspensions. Furthermore, immunohistological analyses were performed on the tumors to detect, quantitate, and determine the distribution of T-lymphocytes and macrophages. The T-lymphocyte content of small tumors was very high, and the T-cells were distributed throughout the tumor mass. As the tumor increased in size, there was a marked decrease in the relative T-cell content; most were located at the tumor periphery. Macrophages were present in significant numers in all tumors and appeared to increase in number as the tumors increased in size. Macrophages were distributed throughout the tumor mass, but generally they were more densely distributed near the tumor periphery. Granulocytes were present in low numbers in all tumors. Yeast phagocytosis was used to assess the functional capacity of the macrophage population. The phagocytic capacity of the macrophages was low in the small tumors, increased significantly as the tumors progressed, but dropped to relatively low levels in large tumors. The results represent a preliminary attempt to characterize the dynamics of host cell infiltration of primary immunogenic tumors.