CD4 and cytomegalovirus infection: Thus, these results confirm the better ability of CD4+ than CD8+ T cell measurements to identify patients with protective immunity, mostly because a long-term protection from HCMV infection is achieved when the CD4+ T cell response is restored [11,25,32,33,34,35,36]; moreover, CD8+ T cells seem to be not protective in the absence of their CD4+ T cell counterpart [11,32,37].