[Effect of intratumor macrophages on the growth of a rat sarcoma]

The removal of active phagocytic cells (CFA) from suspensions of a rat sarcoma (S-E 100) caused a decrease in tumor development in "m" line rats; consequently, we postulated that the macrophage (M phi) population infiltrating the tumor might possess inhibitory functions. In the present paper we investigate whether the effect of CFA is a general one or whether it is dependent on the interaction between M phi infiltrating the tumor and the recipient. S-E 100 was inoculated in "m" line rats (S-E 100,m) and in "c" (S-E 100,c); CFA were depleted from both tumoral suspensions with carbonyl iron powder (FeC), inoculating the supernatant tumor sells denominated S.FeC-m and S.FeC-c, and the corresponding control suspensions, S Te-m and S Te-c. Inocula for both recipients were subcutaneous and contained 1 x 10(6) cells. The elimination of CFA induced a decrease in the development of the tumor in "m" recipients only when the inoculum was provided by S-E 100, m (Table 1). On the contrary no change in tumor growth was detected in the "C" recipients, whether the inoculum was provided by SE-100, m or by S-E 100, c (Table 1). An inhibitory effect on the immune response exerted by M phi infiltrating S-E 100, as a non general effect, is postulated. This effect was obtained only when intratumoral M phi were syngeneic with the recipient and specifically for "m" line.