Dispensability of surfactant proteins A and D in immune control of Mycobacterium tuberculosis infection following aerosol challenge of mice.

Surfactant proteins A and D (SP-A and -D) play a role in many acute bacterial, viral, and fungal infections and in acute allergic responses. In vitro, human SPs bind Mycobacterium tuberculosis and alter human and rat macrophage-mediated functions. Here we report the roles of SP-A and SP-D in M. tuberculosis infection following aerosol challenge of SP-A-, SP-D-, and SP-A/-D-deficient mice. These studies surprisingly identified no gross defects in uptake or immune control of M. tuberculosis in SP-A-, SP-D-, and SP-A/-D-deficient mice. While both SP-A- and SP-D-deficient mice exhibited evidence of immunopathologic defects, the CD11b(high) CD11c(high) dendritic cell populations and the gamma interferon (IFN-γ)-dependent CD4(+) T cell response to M. tuberculosis were unaltered in all genotypes tested. Together, these data indicate that SP-A and SP-D are dispensable for immune control of M. tuberculosis in a low-dose, aerosol challenge, murine model of tuberculosis (TB).