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

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.