Cell Mediated Responses To The Mycobacterium tuberculosis Specific ESAT-6 Antigen in Egyptian Tuberculosis Patients

¹Maha S. Abd El-Maged, ²Sahar A. Shoman, ³Maged M. Al-Sherbieny, and ²Ahmed B. Barakat

¹Egyptian Organization for Biological Products and Vaccines (VACSERA Holding Company), ²Microbiology Department, Faculty of Science, Ain Shams University, and ³Zoology Department, Faculty of Science, Cairo University, Cairo, Egypt.

Human T cell responses and gamma interferon (IFN-g) secretion by peripheral blood mononuclear cells (PBMCs) in response to M. tuberculosis Early Secretory Antigen Target-6 (ESAT-6) eight synthetic overlapping peptides, were investigated in Egyptian tuberculosis patients as well as a control group. Three cell mediated immunoassays (lymphoproliferative, ELISPOT and intracellular flowcytometry) have been employed in this study to determine the ability of ESAT-6 to induce T-cell responses and IFN-g secretion, which play a critical role in protective cell-mediated immunity against tuberculosis (TB). The results revealed that all ESAT-6 peptides (P1-P8) were recognized by 85% of infected TB- patients, indicating that the molecule holds multiple epitopes. However, patients differed in the fine specificity of their peptide responses. Recognition of the N-terminal region of (P2-P7) was predominant. This study demonstrates that ESAT-6 is frequently recognized during infection and holds potential as a component of a future TB-vaccine.