Effects of frequent and sustained plateletapheresis on peripheral blood mononuclear cell populations and lymphocyte functions of normal volunteer donors

Per procedure, plateletapheresis may remove 2×109 to 3×109 white cells from the peripheral blood of a normal donor. To investigate the effects of frequent and sustained plateletapheresis, multiple peripheral blood tests were performed on 25 volunteer donors undergoing plateletapheresis an average of 72 times over periods of up to 8 years, and results were compared with 25 age- and sex-matched controls who had not undergone apheresis. In donors, significant decreases were observed in: 1) both absolute number and percentage of T4+ cells; 2) absolute number of both T8+ cells and LeU-7+ cells; 3) T4/T8 ratio; 4) responses to both pokeweed mitogen and alloantigens; and 5) IgG levels. Significant increases were observed in percentages of both B cells and monocytes, and responses to both phytohemagglutinin and Concanavalin A. Plateletapheresis removes a large number of T4 and T8 cells, a moderate number of B cells, and a smaller number of monocytes and Leu-7 cells. The results suggest that during vigorous plateletapheresis the replenishment to peripheral blood per month was less than 1.83×109 and 0.93×109 for T4 cells and T8 cells, respectively, greater than 0.27×109 and 0.62×109 for B cells and monocytes, respectively, and approximately 0.39×109 for Leu-7 cells. Although no clinical effect was noted, these data suggest that frequent and sustained non-lymphocyte sparing plateletapheresis is associated with changes in laboratory findings related to the immune system.