Evaluation of the immune response in mice infected with Mycobacterium marinum.

Foot pad infection of mice with Mycobacterium marinum carried out with a view to comparing the immune response on the humoral level of such mice, with that observed previously in mice infected with M. leprae, indicated that there was a similarity in terms of the first appearance and proliferation of immunocytes and the time at which the peak and decline in the antibody-producing cells occurred. The significant difference appeared to be in the immunoglobulin G response, which was absent in the M. leprae infected mice, but occurred simultaneously with the immunoglobulin M response at a high level, both during a primary and after a secondary challenge administered 15 days post-primary infection in the M. marinum infected mice. Further confirmation was obtained through additional studies on the specific immunoglobulin levels and determination of both immunoglobulin M and immunoglobulin G antibodies by hemagglutination. Although the growth temperature requirement of the two organisms and their ability to initiate infection in areas of the body with lower temperatures are similar, it is suggested that the type of infection induced by each one of these species in the mouse may disallow the serious consideration of the M. marinum infection model as a possible alternative experimental model for studying the role of host immunity to M. leprae infections in mice.