AUGMENTATION OF MACROPHAGE PHAGOCYTIC-ACTIVITY BY CELL-FREE-EXTRACTS OF SELECTED LACTIC ACID-PRODUCING BACTERIA

Oral and intraperitoneal administration of lactic acid-producing bacte ria can significantly augment the immune response in murine models; ho wever, the immunopotentiating effects in these studies differ signific antly. Murine macrophagelike cell line J774 was cultured in the presen ce of cell-free extracts of Lactobacillus acidophilus and Bifidobacter ium longum, and the effect on macrophage function was evaluated by mea surement of synthesis of selected enzymes and their ability to take up either acrylamide particles or live Salmonella typhimurium. Lysozyme activity of J774 cells was significantly decreased by cell-free extrac ts of B. longum, but not of L. acidophilus, whereas extracts of both s trains induced morphological changes and significantly enhanced phagoc ytosis of inert particles or viable Salmonella. Whole cell extracts of lactic acid-producing bacteria are therefore capable of altering macr ophage function in a strain-dependent manner.