Antibody response to phenolic glycolipid I and Mycobacterium w antigens and its relation to bacterial load in M. leprae -infected mice and leprosy patients.

Moudgil, K.D.; Gupta, S.K.; Narayanan, P.R.; Srivastava, L.M.; Mishra, R.S.; Talwar, G.P.

Clinical and Experimental Immunology; 1989; 78; 214-218.

Twenty six inbred BALB/cBy mice were infected with live Mycobacterium leprae by injecting 6 x 10 3 bacilli in the hind footpad. Bleeds were collected at monthly intervals. After 6 months, acid-fast bacilli (AFB) were harvested monthly from the footpad of mice. The sera were analysed in enzyme immunoassay for antibodies against phenolic glycoipid-I (PGL-I) of M. leprae and antigens of Mycobacterium w (M-W); 21 out of 26 (80.7%) mice demonstrated the presence of antibodies against PGL-I and M-w, Anti-M-w antibodies appeared slightly earlier than did anti-PGL-I antibodies. The titre of anti-M-w antibodies was higher than of anti-PGL-I antibodies. The mice giving a positive antibody response had more than 7x10 3 AFB/footpad. The coefficient of correlation (r) between the number of AFB and antibody titres at the time of harvest was 0.556 for PGL-I and 0.628 for M-w. The value of r for bacterial index and antibody titres in 188 leprosy patients was 0.510 for PGL-I and 0.418 for M-w; these values were statistically significant (p < 0.001). The decrease in bacterial index and antibody titres in treated lepromatous leprosy patients correlated with increase in the duration of chemotherapy. The measurement of anti-PGL-I antibodies of IgM class may serve as an adjunct to skin biopsy and skin-slit smear for serial monitoring of the bacterial load in the course of chemotherapy in leprosy control programmes.


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