In addition, Con A, complex mycobacterial antigens and peptides of RD1 were used as controls. In a previous study, peptide pools covering the sequence of all ORFS of each RD deleted in all strains of M. bovis BCG, i.e. RD1, RD4–RD7, RD9–RD13 and RD15, have been tested in the above assays using PBMC obtained from culture-proven pulmonary TB patients (Al-Attiyah & Mustafa, 2008). The results showed differential effects of peptide pools of various RDs on the secretion of IFN-γ and IL-10 by PBMC, with low IFN-γ : IL-10 ratios (<1.0) in response

to RD12, RD13 and RD15, suggesting that these RDs may be involved in the pathogenesis of TB (Al-Attiyah & Mustafa, 2008). However, the focus of this study check details was RD15 because this region contains genes that encode Mce3 proteins, which may contribute to the pathogenesis of TB by facilitating the entry and survival of M. tuberculosis in host cells (Gioffréet al., 2005; El-Shazly et al., 2007; Senaratne et al., 2008). Therefore, analyses of the cellular immune responses to peptides of RD15 in TB patients and healthy subjects, with respect to

the target molecules recognized and the type of immune response induced, could be important to the understanding of protective and pathological immune mechanisms AZD1208 in TB. Furthermore, such analyses may also help in the identification of antigens suitable for the diagnosis and development of new vaccines against TB (Flynn, 2004; Mustafa,

2005a). To our knowledge, this is the first study to evaluate the cellular immune responses in TB patients and healthy subjects Liothyronine Sodium to the ORFs of RD15 of M. tuberculosis. Similar studies have previously been performed with peptides of RD1, which have shown that RD1 peptides are strong and moderate stimulators of cellular immune responses in TB patients and healthy subjects, respectively (Hanif et al., 2008; Mustafa et al., 2008). Therefore, RD1 peptides were included in this study as a reference with which to compare the cellular responses induced by peptides of RD15. The results showed that PBMC from both TB patients and healthy subjects mounted strong cellular immune responses to Con A and complex mycobacterial antigens, as indicated by strong lymphocyte proliferation and IFN-γ secretion by PBMC. These results indicate that both groups of subjects were immunocompetent, and therefore suitable for studying the cellular immune responses to peptides of RD15. Furthermore, RD1 peptides induced strong proliferation and IFN-γ responses in TB patients and moderate responses in healthy subjects, confirming our previous findings in different groups of donors (Hanif et al., 2008; Mustafa et al., 2008). Although RD1 is deleted in all strains of M. bovis BCG vaccines (Behr et al., 1999), the moderate responses to RD1 in M.