CD4 and infection: It has been postulated that thrombocytopenia, which is a very common finding in patients suffering from HIV disease, may be due to infection of megakaryocytes; however, in the absence of productive infection, HIV-1 has been shown to negatively affect the survival and maturation of HPCs towards megakaryocytes, and it has been suggested that gp120–CD4 interaction may be mediating the observed effect [31].