Phenotypic characterization of Peripheral B cells in Mycobacterium tuberculosis infection and disease in Addis Ababa, Ethiopia.

Background: Mortality and morbidity from tuberculosis (TB) remain one of the most important public health issues. Although cell-mediated immunity is the main immune response against Mycobacterium tuberculosis (MTB), the role of B-cells during MTB infection and disease is unclear.

Methods: Peripheral blood mononuclear cells (PBMC) were isolated from treatment naïve Pulmonary TB patients (TB, n = 16), latent TB-infected participants (LTBI, n = 17), and healthy controls (HC, n = 19). PBMCs were stained with various fluorescently labeled antibodies to define B-cell subsets using multicolor flow cytometry.

Results: Atypical memory B cells (CD19+CD27-CD21-) and circulating marginal zone B-cells (CD19+CD27+CD21+IgM+IgD+CD23-) were significantly higher in active TB when compared to LTBI and HC. CD5+ regulatory B cells (Breg, CD19+CD24hiCD38hiCD5+) and resting B-cells (CD19+CD27+CD21+) in Active TB patients were significantly lower compared to HC and LTBI. Overall, there were no differences in B cell percentages (CD19+), naïve B cells (CD19+CD27-CD21+), Breg (CD19+CD24hiCD38hi), and activated memory B cells (CD19+CD27+CD21-) among the three study groups.

Conclusions: These results indicated that multiple subsets of B cells were associated with TB infection and disease. It will be useful to examine these cell populations for their potential use as biomarkers for TB disease and LTBI.