Similarly, DAP12 down-modulates the cytokine production by plasmacytoid dendritic cell in vivo during murine cytomegalovirus infection (40) and DAP12-deficient B cells are hyper-responsive after stimulation with anti-IgM or CpG, suggesting that DAP12-coupled receptors negatively regulate B cell-mediated adaptive immune responses (41). Here, CD40LG is linked to cytomegalovirus infection.