Blood counts. (A-B) CD4⁺ and CD8⁺ counts for the 3 groups. Donors who have undergone 20 to 24 successful plateletpheresis sessions in a 365-day period at any point in the prior 20 years are indicated by blue symbols. The dotted line indicates 200 cells per microliter (A) and the lower limit of normal (B). (C) CD4⁺ counts relative to the total number of plateletpheresis sessions in the prior 20 years; the horizontal dotted line indicates 200 cells per microliter; the vertical dotted line indicates 50 sessions. (D) CD8⁺ counts relative to the total number of plateletpheresis sessions in the prior 20 years; the horizontal dotted line indicates the lower limit of normal; the vertical dotted line indicates 50 sessions. Absolute lymphocyte (E) and monocyte (F) counts for the 3 groups; the dotted lines indicate the lower limit of normal. (G) White blood cell count, hematocrit, and platelet count for the 3 groups. Short horizontal lines indicate the median and interquartile range. All blood counts in this figure were obtained immediately before plateletpheresis. Asterisks denote P values that retain significance after Bonferroni correction for multiple testing. The caret (^) denotes a P value that does not retain significance after Bonferroni correction for multiple testing.