CD4 and infection: More recently, a handful of studies have identified substantial changes in adipose tissue T cell density and cellular characteristics in human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV; a non-human primate virus similar to HIV) infection, including shifts in total CD4+ and CD8+ T cells and subsets, cytokine production, antigen specificity, interactions with adipocytes and other SVF cells, and capacity for latent infection with HIV or SIV proviruses (1–6).