CD4 and cytomegalovirus infection: This modulation of the CD4+ T cell function also extends to HCMV-specific CD4+ T cells which have a regulatory cell phenotype or secrete cIL-10 [14,26,27,28,29,30,31], and have been observed to play an important role in resolving the complications from HCMV infection in hematopoietic stem cell transplant patients [32].