Immune Correlates of Disseminated BCG Infection in IL12RB1-Deficient Mice.

Interleukin-12 receptor β1 (IL12RB1)-deficient individuals show increased susceptibilities to local or disseminated BCG infection and environmental mycobacteria infection. However, the low clinical penetrance of IL12RB1 deficiency and low recurrence rate of mycobacteria infection suggest that protective immunity still exists in this population. In this study, we investigated the mechanism of tuberculosis suppression using the IL12RB1-deficient mouse model. Our results manifested that mice had significantly increased CFU counts in spleens and lungs, especially when BCG (Danish strain) was inoculated subcutaneously. The innate TNF-a and IFN-γ responses decreased, while the IL-17 responses increased significantly in the lungs of mice. We also found that PPD-specific IFN-γ release was impaired in mice, but the specific TNF-a release was not compromised, and the antibody responses were significantly enhanced. Moreover, correlation analyses revealed that both the innate and PPD-specific IFN-γ responses positively correlated with CFU counts, whereas the innate IL-12a levels negatively correlated with CFU counts in mice lungs. Collectively, these findings proved that the adaptive immunities against mycobacteria are not completely nullified in mice. Additionally, our results imply that IFN-γ responses alone might not be able to contain BCGitis in the setting of IL12RB1 deficiency.