CD4 and cytomegalovirus infection: Among the assays measuring the absolute number of HCMV-specific CD4+ T cells, the CD4+ CFC-iDC assay showed the best sensitivity in detecting the HCMV-specific T cell recovery after transplantation, while the CD4+ CFC-pp65 pool assay had better specificity in predicting self-resolving HCMV infections.