Background
The role of B cells in human host response to Mycobacterium tuberculosis (Mtb) infection is still controversial, but recent evidence suggest that B cell follicle like structures within the lung may influence host responses through regulation of the local cytokine environment. A candidate for such regulation could be the chemokine CXCL10. CXCL10 is mainly produced by human monocytes, but a few reports have also found CXCL10 production by human B cells. The objective of this study was to investigate CXCL10 production by human B cells in response to in vitro stimulation with Mtb antigens.

Methodology/principal findings
We analyzed human blood samples from 30 volunteer donors using multiparameter flow cytometry, and identified a subgroup of B cells producing CXCL10 in response to in vitro stimulation with antigens. T cells did not produce CXCL10, but CXCL10 production by B cells appeared to be mediated via IFN-γ and dependent on contact with antigen-specific T cells recognizing the antigen.

Conclusion
Human B cells are able to produce CXCL10 in an IFN-γ and T cell contact-dependent manner. The present findings suggest a possible mechanism through which B cells in part may influence granuloma formation in human tuberculosis (TB) and participate in infection control.