Introduction B cells classically provide humoral immunity in the form of antibody production as part of the adaptive immune response. Regulatory and antigen presenting functions of B cells have been reported before and autoantibodies are associated with autoimmune liver diseases. B cell depletion in animal models of PBC has highlighted the regulatory roles of B cells in ameliorating disease. Some evidence of efficacy of anti-B cell therapy using rituximab in human autoimmune liver diseases further supports a role for B cells. Mature B cells (Bm) subpopulations had been described in Sjogren’s syndrome. However, little is known about the localisation, subsets, phenotype and function of B cells in human liver diseases.
Methods In this study we characterised the frequencies of B cell subsets in the blood and liver of patients with inflammatory and autoimmune liver diseases.
Results Frequencies of naïve mature BM1 cells were reduced in the liver compared to blood (7.5% ± 2.3 vs. 20.2% ±2.8 p = 0.0022) and IgDnegCD27neg subset was increased in diseased livers compared to diseased blood (22.9% ± 6.8 vs. 6.0% ± 1.1 p = 0.0013). B cells localise close to the bile ducts in PBC and reside around hepatocytes in AIH. Frequencies of regulatory B cells (CD19posCD24hiCD38hi) were significantly reduced in diseased blood vs. control blood (1.8% ± 0.4 vs. 3.6% ± 0.5 p = 0.01) similar to recent observation in acute rheumatoid arthritis. However this population is increased in the diseased liver compared with blood (6.2% ± 0.07 vs. 1.8% ± 0.4 p = 0.007), suggesting enrichment of regulatory B cells within the inflamed liver. Liver infiltrating B cells were capable of IL-10 production.
Conclusion We have characterised for the first time the heterogeneity of B cell subsets and presence of regulatory B cells and IL-10 secreting B cells in human diseased livers. We showed that B cells reside close to bile ducts along with other immune cells; thus B cells may play a role in biliary pathology.
Disclosure of Interest None Declared.
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