Comparative Studies on the Phagocytosis of Bacteria by Connective Tissue Cells

Abstract

Subcutaneous insertions of mica platelet smeared with dead bacteria were performed on mice. These were removed after lapse of a definite time. The reactions of the connective tissue cells were then examined by supravital staining and, after formalin fixation, by other staining methods. Fibrohistiocytes and histiocytes were strongly phagocytic on all of the bacteria. Monocytes, leucocytic cells and fibrocytes showed phagocytic activity in this respective order. Monocytes and fibrocytes showed somewhat stronger phagocytic activity on micobacterium tuberculosis compared with other bacteria. In a few days, giant cells which had engulfed the bacteria were seen. As for the size and number of vacuoles appearing in the cytplasm, in the case with bacillus typhosus this was especially notable; mycobact. tuberculosis, b. dysenteriae, b. paratyphosus A, b. coli and staphylococcus ranked in this respective order. In the case of monilia albicans (thrush-fungi) and b. subtilis, the vacuoles were small in number, but large in size. In the case of mycobact. tuberculosis, the vacuoles remained for a long period within the cell. About the time the cells began phagocytosis of the bacteria, the pH of vacuoles generally ranged from 7.2 to 7.8; as the digestion of the bacteria progressed, most of the pH dropped below 7.0. In regard to the speed of digestion of bacteria within the vacuoles, intestinal bacilli and streptococci ranked first with thrush-fungi following. Bacilli subtilis and mycobact. tuberculosis required much time. As to how the bacteria were digested, intestinal bacilli quickly changed their shape from rod to small round; staphylococcus was broken up into small pieces in about the same speed as the intestinal bacilli; thrush-fungus was reduced to pseudomorphous and gradually became smaller; b. subtilis generally became smaller by degree; most of the mycobact. tuberculosis of filiform shape were cut into rosary shapes or into rods and became thinner and smaller.