The effect of in vivo modulation of macrophage activities on Mycobacterium lepraemurium infection.

During the early stage of Mycobacterium lepraemurium (MLM) infection in mice, the mononuclear phagocyte system (MPS) was activated non-specifically as demonstrated by enhanced listericidal activity. Such listericidal activity could be further increased by Corynebacterium parvum treatment, indicating that MLM was not a good MPS stimulant. Corynebacterium parvum treatment conferred only marginal protection upon mice during MLM infection, as shown by the slight but significant prolongation of survival time and decreased bacillary load. In contrast, mice could not control splenic Listeria growth in the later stage of infection regardless of C. parvum treatment. Adoptive transfer of Listeria-immune spleen lymphocytes, however, did significantly suppress splenic Listeria growth. The significance of these findings is discussed.