Immune responses in Mycoplasma pneumoniae infection of infant mouse and of man.
Infant mice (2 to 4 days old) were exposed to living Mycoplasma pneumoniae. The organisms were isolated in the order of 10(3) to 10(4) colony-forming units from the lungs of mice for 2 weeks after infection. Mononuclear cell infiltration was present in the lungs of infected mice. The specific IgG antibodies to membrane proteins of M. pneumoniae in the sera of infected mice were detected by enzyme-linked immunosorbent assay for about 800 days. In immunoblotting analysis, a 160-kilodalton (kDa) protein strongly reacted with the infected mouse sera. The dams immunized with membrane proteins conferred passive immunity on their offspring via colostrum. Specific IgG antibody appeared in the serum of infant mice that were given mouse anti-M. pneumoniae serum or convalescent human patient serum orally. These mice were also protected from challenge with M. pneumoniae. The immunoblotting patterns of patient sera were similar to those of infected mouse sera. The infant mouse model may be useful to investigate the host immune responses to M. pneumoniae.