Biomarkers included low numbers and proportions of B cells, high numbers and proportions of late-stage differentiated CD8+ T cells (i.e., CD27−CD28−), poor T cell proliferation in response to mitogens, a CD4:CD8 ratio of <1.0, infection with Cytomegalovirus and high plasma IL-6, which together, predicted greater all-cause mortality at 2-, 4-, and 6-year follow-up (195, 197–200). This evidence concerns the gene CD4 and infection.