Considering we found that BTLA-/- mice were protected from lymphoid cell apoptosis, it is also possible that many of the BTLA+CD4+ T cells in Boomer and colleagues’ study had already undergone apoptosis and were lost by the time these patients had succumbed to sepsis (compared with our data, in which we see a high level of circulating BTLA+CD4+ lymphocytes in septic patients). This evidence concerns the gene CD4 and Sepsis.