CD4 and medical procedure: Apart from analyses of the immediate effector function of CMV-specific T cells, the proliferation of CD4 and CD8 T cells was evaluated in a subset of 15 CMV-seropositive individuals (10 kidney transplant recipients, 5 immunocompetent controls) after stimulation of PBMCs with saturating and low concentrations of CMV lysate (high and low, respectively) in the presence and absence of CMV-IVIg, respectively.