CD4 and AIDS: Immune activation is also associated with chronic inflammation and activation of the coagulation system that increase the risk of ‘serious non-AIDS events' such as atherosclerotic vascular disease, osteoporosis, osteonecrosis and chronic kidney disease.1 Inflammation also affects lymphoid tissue where the resultant tissue fibrosis is a cause of impaired homoeostasis of CD4+ T cells2 and probably memory B cells.