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[Experimental study on prevention of pneumoconiosis complicating with tuberculosis by Mycobacterium vaccae].

OBJECTIVE
To explore the role of Mycobacterium vaccae in prevention of pneumoconiosis complicating with tuberculosis.


METHOD
Mycobacterium vaccae was injected into rats which had been exposed to quartz for 2 weeks, and H37Rv was injected into their tail veins 1 month later. All the rats were killed 3 months later. Indexes for evaluation in the study included tuberculous lesion pathological change index, Mycobacterium tuberculosis culture in a fixed amount in lung tissues, count of Mycobacterium tuberculosis and histopathological changes in alveolar macrophages.


RESULT
Tuberculous lesion pathological change index, Mycobacterium tuberculosis culture in a fixed amount in lung tissues and count of Mycobacterium tuberculosis in alveolar macrophages were 2.6 +/- 0.5, (4.40 +/- 4.00) x 10(4) CFU and 7.2 +/- 3.2 respectively in pneumoconiosis complicated with tuberculosis and injecting Mycobacterium vaccae group, while 3.1 +/- 0.3, (18.9 +/- 18.2) x 10(4) CFU and 12.5 +/- 6.3 respectively in the control group. And statistically significant differences were found between the two groups (P < 0.05, 0.01, 0.05 respectively). The histopathological analysis revealed that proliferative and lymphoid nodules were predominant in the pneumoconiosis complicated with tuberculosis and injecting Mycobacterium vaccae group, while necrotic nodules in the control group.


CONCLUSION
Mycobacterium vaccae might play a role in prevention of pneumoconiosis complicating with tuberculosis.