The clearance of tubercle bacilli and mycobacterial antigen vis a vis the granuloma in different organs of guineapigs.

Shakila, H.; Jayasankar, K.; Ramanathan, V.D.

Indian Journal of Medical Research; 1999; 110; 4-10.     

In the present study, an attempt was made to define the relationship of intact tubercle bacilli and/or their antigenic fragments to a granuloma in the guineapig in order to distinguish an active from a resolving granuloma. In one set of animals, granuloma was induced in the skin by injecting heat-killed Mycobacterium tuberculosis intradermally and in another set, granuloma was produced in the lung and spleen by injecting live M. tuberculosis intramuscularly. The animals were sacrificed at various time points and skin, lung and spleen from the two groups were subjected to histological examination for the presence of granuloma, bacilli and antigenic fragments. In the dermal lesion, intact acid fast bacilli were cleared first by day 42 followed by the removal of their antigenic fragments by day 63 and finally by day 84, the granuloma had resolved completely. Ina the guineapigs infected with live M. tuberculosis , removal of the bacilli followed by the clearance of antigen was observed. Though the granuloma itself did not subside completely in these animals, it was found that there was a reduction in congestion and oedema of the granulomatous area. It is concluded from the results that the demonstration of antigen at the site of lesion may be potentially useful to discriminate between a persisting and a resolving tuberculous granuloma.

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