Susceptibility to Fas and tumor necrosis factor-alpha receptor mediated apoptosis of anti-CD3/anti-CD28-activated umbilical cord blood T cells

Antigen-Specific Priming is Dispensable in Depletion of Apoptosis-Sensitive T Cells for GvHD Prophylaxis

Prophylactic approaches to graft versus host disease (GvHD) have employed both phenotypic reduction of T cells and selective elimination of host-primed donor T cells in vitro and in vivo. An additional approach to GvHD prophylaxis by functional depletion of apoptosis-sensitive donor T cells without host-specific sensitization ex vivo showed remarkable reduction in GHD incidence and severity. We address the role and significance of antigen-specific sensitization of donor T cells and discuss the mechanisms of functional T cell purging by apoptosis for GvHD prevention. Host-specific sensitization is dispensable because migration is antigen-independent and donor T cell sensitization is mediated by multiple and redundant mechanisms of presentation of major and minor histocompatibility complex and tissue antigens by donor and host antigen-presenting cells. Our data suggest that potential murine and human GvH effectors reside within subsets of preactivated T cells susceptible to negative regulation by apoptosis prior to encounter of and sensitization to specific antigens.

Effect of influenza A infection on maturation and function of neonatal monocyte-derived dendritic cells

Dendritic cells (DC) are essential for the first-line innate defense against influenza infection. The greater susceptibility to severe influenza infection in young infants and neonates may be attributed in part to their defective DC function. We sought to investigate the effect of influenza A virus (IAV) infection on the maturation, apoptosis, and function of monocyte-derived dendritic cells (MoDCs) from umbilical cord blood (UCB) and compared this with responses from adult peripheral blood (APB). Our findings were as follows. First, MoDCs derived from UCB showed deficient CD40, CD80, CD86, and HLA-DR upregulation following IAV infection compared to APB MoDCs. Second, IAV induced a multiplicity of infection (MOI)-dependent increase of apoptosis in UCB MoDCs, similar to that observed with APB. Third, the ability of UCB MoDCs to uptake dextran is decreased following IAV infection. Fourth, deficient TNF-α, but not IL-6, IFN-α response was induced by IAV infection of UCB MoDCs. Fifth, the ability of UCB MoDCs to promote allogeneic CD3 T-cell proliferation is inhibited by IAV infection. Taken together, we demonstrated a differential response of UCB and APB MoDCs following IAV infection, which may contribute in part to the increased susceptibility to severe influenza infection observed in young infants and neonates.