Comparison of the changes in CD45RO⁺ CD4 cell levels for 19 patients between the chemotherapy nadir and the peak level of CD4 cells in the early months of follow-up, and between that peak and the lowest level of CD4 cells in the later months of follow-up. Data show that the levels of CD45RO⁺ cells increased from the nadir to the early peak, but then decreased during the latter half of the first year of chemotherapy follow-up. Data from 16 patients were included in both graphs and from six in only one graph because of missing time points. Note that the bar (▪) represents the mean and () SE of the two populations.