PD-1 is a novel regulator of human B-cell activation

Int Immunol. 2013 Feb;25(2):129-37. doi: 10.1093/intimm/dxs098. Epub 2012 Oct 18.


The outcome of the adaptive immune response is determined by the integration of both positive and negative signals, respectively, induced upon the triggering of co-signaling receptors. One of them, programmed cell death 1 (PDCD1/PD-1) has largely been shown to be involved in the negative regulation of T-cell activation. However, PD-1 is also expressed on human B cells, and its role(s) in the process of human B-cell activation remains uncertain thus far. In this study, we describe the expression of PD-1 on the major human B-cells subsets isolated from peripheral blood and lymph nodes. We showed that PD-1 was expressed on naive B cells, was differentially expressed on peripheral IgM memory as compared with memory B cells and was lost on germinal center B cells. Expression of PD-1 ligands (PD-Ls) was induced by TLR9 activation. Finally, we showed that PD-1 was recruited to the B-cell receptor upon triggering. We determined that during TLR9 activation, blockade of PD-1/PD-Ls pathways indeed increased B-cell activation, proliferation and the production of inflammatory cytokines. Altogether, our results show, that, as reported in T cells, PD-1/PD-Ls complexes acted as inhibitors of the B-cell activation cascade and highlight the importance of devising future therapies able to modulate lymphocyte activation through the targeting of the PD-1/PD-Ls pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • B-Lymphocytes / cytology*
  • B-Lymphocytes / immunology*
  • Humans
  • Lymphocyte Activation*
  • Programmed Cell Death 1 Receptor / biosynthesis
  • Programmed Cell Death 1 Receptor / immunology*


  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor