BCG vaccination in South India does not enhance antimycobacterial activity in peripheral blood monocytes - direct contrast with results in Britain

Lowrie, D B and Cheng, S H and Swamy, Raji and Narayanan, P R and Sharma, V S N and Walker, K B and Aber, V R and Mitchison, D A (1989) BCG vaccination in South India does not enhance antimycobacterial activity in peripheral blood monocytes - direct contrast with results in Britain. Journal of Medical Microbiology, 28. xi. ISSN Print: 0022-2615; Online: 1473-5644

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Abstract

Blood was taken immediately before vaccination of skin-test-negative individuals in South India and Britain (mean age 16.1 years in India, 13.5 in Britain) and again 8 weeks after vaccination. Tests of monocyte antimycobacterial activity were done by the same operator (S.H.C.) in London and Madras. Monocytes were infected with Mycobacterium microti, exposed to autologous lymphocytes reacting with whole dead (y irradiated) M . tuberculosis H37Rv antigen and bacterial growth rates (cfu) were assessed. With British subjects, growth rates were significantly higher before than after vaccination (mean log,, cfu/day was 0.33 before and 0.18 after; p < 0.001, n = 8 ) ; with Indian subjects vaccination had no effect (0- 10 before and 0.19 after; p < 0.16, n = 7). Prevaccination growth rates were significantly higher with British than with Indian subjects (p < 0.001). The Indian subjects were all skin-test-negative to 4 IU PPDs before vaccination (48-h reaction diameter < 8 mm, mean 4.9 f 0.2 mm). However, Indian subjects differed from British in being skin-test-positive to 10 IU PPD-B before vaccination (12.7 f 0.7 mm), presumably reflecting exposure to the common environmental mycobacteria in South India. It appears that the failure of BCG vaccination to confer protection against tuberculosis in a major clinical trial in South India can be ascribed to the presence of a pre-existing anti-mycobacterial immunity which might be due to sensitsation by environmental mycobacteria.

Item Type:	Article
Subjects:	Tuberculosis > Clinical Research
Divisions:	Clinical Research
Depositing User:	Dr. Rathinasabapati R
Date Deposited:	27 Aug 2013 11:28
Last Modified:	14 Mar 2016 10:11
URI:	http://eprints.nirt.res.in/id/eprint/256

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