The importance of B cells in collagen-induced arthritis led us to investigate whether particular B cell subsets participate in the autoimmune response to collagen type II. We show here that MZB cells in the spleen are naturally self-reactive to collagen type II and are the first cells to expand after collagen type II immunization. In contrast, the autoimmune collagen type II response in lymph nodes develops one week later. Due to this time lapse we hypothesized that the MZB cells may be involved in initiating the autoimmune response in the lymph nodes. We did indeed find a small MZB-like B cell population in the lymph nodes that expressed B220+CD23loCD1dhi, thereby being distinguishable from FOB cells. The MZB-like cells expanded almost two-fold after immunization with collagen type II but not the control antigen ovalbumin, making this phenomenon specific to the autoimmune response. The MZB-like cells displayed an antigen activated phenotype with increased cell surface expression of MHCII, FcγRIIb and CD70. Moreover, after immunization the MZB-like cells increased their expression of CXCR5, implying that they are migrating cells. Further investigation of the specific function of the MZB-like cells is warranted. In conclusion, MZB cells in the spleen trigger the autoimmune collagen type II response in collagen-induced arthritis, and a MZB-like population in the lymph nodes is specific for the autoimmune reaction and may be of importance for disease pathogenesis in this model.
- Copyright © 2013 by The American Association of Immunologists, Inc.