Human leukocyte antigen-G (HLA-G) is an anti-inflammatory and immunosuppressive molecule that can modulate immune cell activation. The role of HLA-G in tuberculosis, an immune-mediated and chronic bacterial disease remains to be elucidated. We investigated the expression profile of soluble and membrane bound HLA-G in pulmonary TB (PTB), TB pleural effusion (TB-PE, localized disease) and Miliary TB (disseminated form). The expression of HLA-G receptor, ILT-2 was also determined on the immune cells. We observed that the plasma sHLA-G levels were significantly increased in Miliary TB than in TB-PE patients. In contrast, immunophenotyping revealed that the percent frequency of CD3+ T cells expressing HLA-G was significantly reduced in Miliary TB as compared to TB-PE, whereas frequency of CD14+ monocytes expressing HLA-G was significantly higher in TB-PE patients. Strikingly in the TB-PE cases, comparison of disease site, i.e. pleural effusion with peripheral blood showed increased expression of both soluble and surface HLA-G, whereas ILT-2 expressing cells were reduced at the local disease site. Furthermore, we demonstrated that in TB-PE cases, HLA-G expression on CD3+ T cells was influenced by broad spectrum MMP inhibitor. Thus, differential expression of HLA-G could potentially be a useful biomarker to distinguish different states of TB disease.
Bibliographical noteFunding Information:
The authors sincerely wish to acknowledge the financial support provided by the Indian Council of Medical Research – India (ICMR letter No. 5/8/5/7/2012-ECD-I, dated 11th June, 2012) and Dr. Manjula Singh for coordinating the project related activities at ICMR. The study was approved by the Ethics committee of the All India Institute of Medical Sciences (letter No. IEC/NP-85/2012 & RP-09/2012) and the Rajan Babu Tuberculosis & Chest Hospital (2048/RBIPMT/2014).
© 2016 American Society for Histocompatibility and Immunogenetics
- Miliary tuberculosis
- Tuberculosis-pleural effusion