Susceptibility to Mycobacterium avium of Various Inbred Strains of Mice

Intraperitoneal and subcutaneous infections with M. avium, strain Kirchberg, were made in BALB/c-nu/nu mice and hybrid-nu/nu mice of C3H origin to see the relation between development of the lesions and cell-mediated immunity in the hosts. Mice of KK, BALB/c and C3H strains were also infected, as controls.There were no differences in the development of visceral lesions and average survival time between BALB/c-nu/nu and BALB/c mice infected intraperitoneally with 0.5mg of M. avium, because the inoculum size was so large. On the other hand, 4 of 8 infected hybrid-nu/nu mice of C3H origin were highly resistant to M, avium infection, such as observed in C3H mice, under the same situation.In BALB/c-nu/nu mice subcutaneously infected with 0.025mg of M, avium, subcutaneous lesion at the inoculation site reached to a large flattened granuloma, whereas very small, hard and sharply defined nodule was found in conventional mice of C3H and BALB/c strains. On the contray, no palpable lesion was observed in roughly half of hybrid-nu/nu mice of C3H origin, although the remaining nude mice showed the similar susceptibility to that of BALB/c-nu/nu mice.These results reveal that the high resistance to M. avium shown in C3H mice has no connection with developing cell-mediated immunity in the hosts.