An assessment of intratumor phagocytic and surface marker-bearing cells in a series of autochthonous and early passaged chemically induced murine sarcomas.

Single cell suspensions from five different 3-methylcholanthrene-induced tumors in CBA mice were examined in the autochthonous host and sequentially for 5-11 passages. They were also examined for Fc receptor-bearing, phagocytic, theta antigen-positive, and surface immunoglobulin-bearing cells. The preparations contained a high proportion of phagocytic and marker-bearing cells both in the original host and during early passage. This proportion was consistent for any particular tumor and passage. Between different tumors, however, the proportions were sufficiently different to allow the tumor to be identified on this basis; this suggested that various chemically induced tumors may be unique in their tumor-host relationship as measured by the type of cells which infiltrate them. With on-going early passage of the tumors, the proportion of marker-bearing cells decreased to a constant level in most instances, mainly because of a reduction in the percentage of phagocytic cells. The tumor with the least macrophages (MBQA, less than 5%) consistently appeared more rapidly and killed the host more rapidly than did the tumor with the most macrophages (MBQD, 15-30%), but was not significantly different in its growth rate. The theta antigen- and Fc receptor-positive cells within these tumors were derived from the animal receiving the tumor inoculum, and thus represented host cell infiltration of the tumor. The results were discussed with reference to fundamental concepts of the immunology of chemically induced tumors and the importance of host cell infiltration within these tumors.