B-cells with a FasL expressing regulatory phenotype are induced following successful anti-tuberculosis treatment:

Abstract

Introduction: Studies show that B-cells, in addition to producing antibodies and antigen-presentation, are able to produce cytokines as well. These include regulatory cytokines such as IL-10 by regulatory B-cells. Furthermore, a rare regulatory subset of B-cells have the potential to express FasL, which is a death-inducing ligand. This subset of B-cells have a positive role during autoimmune disease, but has not yet been studied during tuberculosis. These FasL-expressing B-cells are induced by bacterial LPS and CpG, thus we hypothesized that this phenotype might be induced during tuberculosis as well. Methods: B-cells from participants with TB (at diagnosis and during treatment) and controls were collected, and analyzed by means of real-time PCR and flow cytometry. In addition to this, BAL was collected from TB participants as well and analyzed by means of MAGPix (multi-cytokine) technology. Results: Gene expression analysis show that FASL transcript levels increase by the end of treatment. Similarly, phenotypic analysis show that there is a higher frequency of FasL-expressing B-cells by the end of treatment. Conclusion: Collectively, these results indicate that these FasL-expressing B-cells are being induced during anti-TB treatment, and thus may play a positive role. Further studies are required to elucidate this. Successful Tuberculosis treatment induces B-lymphocytes expressing the FasL receptor that may be important for protection. Regulatory (killer) B cells may have an important role as part of restoration of the immune system.