CD4 and HIV infectious disease: In fact, Blanche et al. 22 showed that, after a mean of 17 years of HIV infection (meaning patients 10 years younger than ours), thymic activity (measured as CD4+ CD45RA+ CD31+ recent thymic emigrants or RTE) and naïve CD4+ cells number were conserved, while RTE positively correlated with CD4+ cells current number.