Effect of cyclophosphamide treatment on the course of Mycobacterium lepraemurium infection and development of delayed-type hypersensitivity reactions in C57B1 and BALB/c mice.

Pre-treatment of Mycobacterium lepraemurium susceptible, BALB/c, and resistant, C57Bl, mice with cyclophosphamide markedly altered the development of delayed hypersensitivity during footpad infections with this organism. A tuberculin-type response demonstrated by untreated C57Bl mice was significantly intensified after week 3 in cyclophosphamide-pre-treated mice although this response had returned to normal levels by week 8. A Jones-Mote-type response demonstrated throughout experiments by untreated BALB/c mice was considerably increased in magnitude by week 3 in cyclophosphamide-pre-treated mice. By week 6 this response had become considerably protracted and was of the tuberculin-type. By week 8 however this response had started to diminish and by week 12 cyclophosphamide-treated and untreated BALB/c mice produced similar Jones-Mote-type responses when skin-tested. Cyclophosphamide pre-treatment had no effect on the growth of M. lepraemurium in C57Bl mice over 12 weeks. In BALB/c mice however cyclophosphamide-pre-treated mice demonstrated considerable resistance to infection at weeks 8 and 10 after infection but not thereafter. Whereas the magnitude of the delayed hypersensitivity response in C57Bl mice could not be correlated with resistance such a relationship could be demonstrated in BALB/c mice.