Investigation of the component of Propionibacterium acnes (Corynebacterium parvum) responsible for macrophage activation.

Mouse peritoneal macrophages, activated with Propionibacterium acnes (Corynebacterium parvum) in vivo, exhibited altered morphological characteristics, increased acid phosphatase activity, and release of [EH]thymidine-labeled DNA from tumor cells in vitro. Comparison with macrophages from mice injected with a control organism, P. jensenii, showed that the morphological changes, but not acid phosphatase, correlated with the development of tumoricidal activity. Investigation of the microbial component responsible for this activity indicated it was heat stable and refractory to extraction by methanol-chloroform, dilute acid, butanol, or a serial combination of extraction procedures. When the cells were disrupted by mechanical breakage, no activity could be found in the cell wall, soluble cytoplasm, or particulate cytoplasm. These results suggest that intact organisms are required for macrophage activation, and they may resolve conflicting reports on the nature of the immunostimulating activity of P. acnes.