Negative control of T_FH cells

Migratory dendritic cells (DCs) deliver antigen to draining lymph nodes for the priming of naive T cells, including follicular helper T cells (T_FH cells). In eLife, Kumamoto et al. describe a subset of migratory DCs that express the transmembrane protein CD301b and negatively regulate the priming of T_FH cells, which diminishes their ability to provide help to germinal center B cells. CD301b⁺ DCs are found in the skin and submucosa of barrier tissues. CD301b⁺ DCs have abundant expression of PD-L1 and PD-L2, ligands for the inhibitory receptor PD-1 that is expressed on T_FH cells. Conditional deletion of CD301b⁺ DCs in mice increases the frequency of antigen-specific T_FH cells and B cells. Transient loss of CD301b⁺ cells enhances antibody responses to protein immunogens; however, increased generation of autoantibodies also occurs. These findings suggest that CD301b⁺ DCs act early in the immune response to limit humoral immunity.

eLife (22 September 2016) 10:7554/eLife.17979.001