[Susceptibility and immune responses to Pneumocystis carinii infection in different strains of mice by contagious transmission].
OBJECTIVE
To explore the susceptibility of different strains of mice to P. carinii infection and the host immune response to the organism.


METHODS
C57BL/6 and BALB/c strains of mice (15 each) were exposed to SCID mice infected with P. carinii by co-housing. Observations were made on the number of parasites in the lungs, level of CD4+ T cell and CD8+ T cell in BALF, and serum IgG at 4, 5 and 6 wk after contagion.


RESULTS
The number of P. carinii grew in the lungs of BALB/c mice was found much greater than those in C57BL/6 mice. A few number of P. carinii cysts were detected in the lungs of both strains of mice by 4 wk after co-housing, the number of cysts increased at 5 wk in the lungs of BALB/c mice but not in that of C57BL/6 mice. P. carinii-specific IgG in the sera and high level of CD62low CD4- and CD8-positive T cells in the lungs were found at 5 wk. The parasites were cleared from the lungs at 6 wk in all infected mice, shortly after acquired immune response was initiated.


CONCLUSIONS
BALB/c mice are more susceptible to P. carinii than the C57BL/6 mice by natural transmission, and all the immunocompetent mice can clear the infection of P. carinii by cellular and humoral immune responses.
An
Chun-li
CL
Department of Pathogenic Biology, China Medical University, Shenyang 110001.
Su
Xiao-ping
XP
Harmsen
A G
AG
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D004198:Disease Susceptibility; D005260:Female; D007074:Immunoglobulin G / Q000097:blood; D008168:Lung / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D045363:Pneumocystis carinii / Q000472:pathogenicity*; D011020:Pneumonia, Pneumocystis / Q000276:immunology* / Q000382:microbiology
D007074:Immunoglobulin G