Macrophage activities in sarcoma 180-bearing mice and EL4-bearing mice.

Four types of macrophage activities were studied in sarcoma 180-bearing ICR mice and EL4-bearing C57BL mice. Sarcoma 180 cells grow very slowly and do not metastasize, while EL4 cells grow very rapidly and metastasize rapidly to the liver. Chemotactic activity of macrophages was significantly reduced from an early stage in both sarcoma 180-bearing ICR mice and EL4-bearing C57BL mice as compared with that in normal mice. Digestive activity, which was determined by following O2- production by chemiluminescence measurements was also reduced from an early stage in tumor-bearing mice, whereas no reduction of engulfment activity of microorganisms was observed until an advanced stage in both sarcoma 180-bearing mice and EL4-bearing mice. In contrast enhancement activity of macrophages in the blastogenic response of spleen lymphocytes to bacterial lipopolysaccharide was retained at the normal level at the early stage of the tumor graft and was reduced in later stages. These results suggest that activities of Ia-negative macrophages were at first depressed generally in tumor-bearing hosts and later the activities of Ia-positive macrophages were depressed by factor(s) which might be produced by tumor cells.