Comparative effects of different strains of Corynebacterium parvum on natural cell-mediated cytotoxicity

Because there are conflicting reports regarding the effects of Corynebacterium parvum (CP) on natural killer (NK) cell activity, several different strains of CP were compared. In replicate experiments, age- and sex-matched mice received 0.25-mg i.p. injections of one of four types of CP; formalin-killed strain 6134; heat-killed strain 6134; formalin-killed strain 5888 (actually Corynebacterium granulosum); or formalin-killed CP from the Pasteur Institute. At various days thereafter, two to three mice from each group were sacrificed to determine spleen weight, cellularity, and NK cell activity versus YAC-1 lymphoma cells. The CP from the Pasteur Institute augmented NK cell activity 3 days following injections; however, the activity returned to normal by Day 7 and remained at that level. On the other hand, strain 5888 did not cause as great an increase in lytic activity as did the Pasteur Institute CP at Day 3; but by Day 10 after injection, NK cell levels were above control, and they remained elevated through Day 21. Both the heat-killed and formalin-killed preparations of strain 6134 stimulated NK cell activity initially but resulted in a loss of activity at the later times tested. Experiments done with different doses and routes of injection yielded similar results. Thus, we were able to demonstrate that different types of CP have different effects on NK cell activity in mice and that the general kinetics of these effects were independent of dose or route of administration.