Enhancement of Host Resistance to Bacterial and Viral Infections by Lactobacillus casei

Microorganisms such as Mycobacterium, Corynebacterium, and Streptococcus and their components enhance resistance to bacterial and viral infections (6, 7, 16, 1823) ; this effect being caused by the direct activation of macrophage functions or T or B cell-mediated macrophage activation (3, 9, 16) . Bloksma et al (4) reported that some lactobacilli, especially Lactobacillus plantarum, have a strong adjuvanticity on the antibody production to sheep erythrocyte and on delayed-type hypersensitivity. Kato et al (8) reported that Lactobacillus casei may induce macrophages that have potent antitumor activity against sarcoma 180 and L1210 leukemia. The objective of the present study was to determine if Lactobacillus, especially L. casei would enhance the host resistance to bacterial and viral infections induced in mice.