MONDAY, Aug. 1 (HealthDay News) -- A subset of regulatory Foxp3+ T cells (T-reg), which express CXCR5 and Bcl-6, localizes to the germinal center in mice and humans and may inhibit germinal center reactions, according to an experimental study published online July 24 in Nature Medicine.
Yeonseok Chung, Ph.D., from the University of Texas M.D. Anderson Cancer Center in Houston, and colleagues investigated a subset of T-reg cells that express CXCR5 and Bcl-6 in mice and humans. Using immunohistochemical analysis of the draining lymph nodes from mice, the location of Foxp3+ T cells was investigated. Adoptive transfer studies were performed to identify the role of these cells in the germinal B center. In humans, immunohistochemical analysis of tonsils was performed.
The investigators found that CXCR5+Bcl-6+ T-reg cells localized to the B cell germinal center in both mice and humans. T-reg cells expressing Bcl-6 and CXCR5 resembled follicular helper T cells. CXCR5+Bcl-6+ T-reg cells were not found in the thymus but were differentiated upon antigenic stimulation from Foxp3-expressing T cell precursor cells, in a Bcl-6-dependent process. Compared with wild type T-reg cells, CXCR5−/− and Bcl-6−/− T-reg cells were less efficient at suppressing the generation of germinal center B cells, affinity maturation of antibodies, and differentiation of plasma cells.
"Our study has unveiled the Bcl-6-CXCR5 axis in T-reg cells as a new mechanism for controlling germinal center responses," the authors write.
Abstract
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