Previous Article | Next Article ![]()
Infection and Immunity, September 2008, p. 4190-4198, Vol. 76, No. 9
0019-9567/08/$08.00+0 doi:10.1128/IAI.00199-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Department of Microbiology, Faculty of Medicine, Kuwait University, Safat 13110, Kuwait
Received 13 February 2008/ Returned for modification 28 March 2008/ Accepted 16 June 2008
Comparative genomics has identified several regions of differences (RDs) between the infectious Mycobacterium tuberculosis and the vaccine strains of Mycobacterium bovis BCG. We aimed to evaluate the cellular immune responses induced by antigens encoded by genes predicted in 11 RDs. Synthetic peptides covering the sequences of RD1, RD4 to RD7, RD9 to RD13, and RD15 were tested for antigen-induced proliferation and secretion of Th1 cytokine, gamma interferon (IFN-
), by peripheral blood mononuclear cells (PBMC) obtained from culture-proven pulmonary tuberculosis (TB) patients and M. bovis BCG-vaccinated healthy subjects. Among the peptide pools, RD1 induced the best responses in both donor groups and in both assays. In addition, testing of TB patients' PBMC for secretion of proinflammatory cytokines (tumor necrosis factor alpha [TNF-
], interleukin 6 [IL-6], IL-8, and IL-1β), Th1 cytokines (IFN-
, IL-2, and TNF-β), and Th2 cytokines (IL-4, IL-5, and IL-10) showed differential effects of RD peptides in the secretion of IFN-
and IL-10, with high IFN-
/IL-10 ratios (32 to 5.0) in response to RD1, RD5, RD7, RD9, and RD10 and low IFN-
/IL-10 ratios (<1.0) in response to RD12, RD13, and RD15. Peptide-mixing experiments with PBMC from healthy subjects showed that secretion of large quantities of IL-10 in response to RD12 and RD13 correlated with inhibition of Th1 responses induced by RD1 peptides. In conclusion, our results suggest that M. tuberculosis RDs can be divided into two major groups—one group that activates PBMC to preferentially secrete IFN-
and another group that activates preferential secretion of IL-10—and that these two groups of RDs may have roles in protection against and pathogenesis of TB, respectively.
Published ahead of print on 23 June 2008.
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»