[Mycobacterium vaccae influences the kinetics of Th1/Th2 cells and expression of iNOS in a marine model of experimental tuberculosis].

OBJECTIVE

To investigate the immunoregulative mechanism of Mycobacterium vaccae by way of molecular pathology.

METHODS

BALB/C mice were randomly divided into three groups: tuberculosis model (A); mice were challenged with H37Rv by their tail veins and then immunized by M. vaccae (B); control mice (N). Immunohistochemistry and pathological slices stained with HE were evaluated to investigate the correlation between the expression of IFN-gamma, IL-4 and iNOS and the type and magnitude of tissue injury.

RESULTS

A predominance of Th1 cells was observed manifested by a high percentage of IFN-gamma positive cells in the inflammatory infiltrate and granulomas demonstrated by immunohistology peaked 6 weeks after infection (0.058 +/- 0.010), and there was a significant increase compared with N group (0.005 +/- 0.020, P < 0.01). This was followed by a chronic advanced phase characterized by pneumonia local necrosis with a Tho balance due to an equivalent proportion of IFN-gamma and IL-4 positive cells in the lung lesions. The iNOS expression was increased in acute phase and decreased in chronic phase. B group had localized lung lesions, proliferate and lymphoid nodules were predominant, there was less necrostic change. A predominance of Th1 cells was observed during the infection changed over time and there was no Tho balance phase occurred. iNOS expression had a higher level during the wholecourse of infection.

CONCLUSION

M. vaccae can enhance the protective immunological response by inducing Th1 response and inhibiting Th2 response.