Repeat plateletpheresis: the effects on the donor and the yield.

Requirements for HLA ot otherwise matched single-donor platelets may sometimes require repeat plateletpheresis of an individual donor. AABB standards permit the repeat collection of platelets by plateletpheresis of a single donor at 48-hour intervals, whereas recent recommendations from England state that a donor should not donate platelets more often than 12 times a year. To assess the effects of repeat plateletpheresis on the donor, we have studied the hematological indices and the product yields following every other day plateletpheresis of 13 normal donors who gave a total of 10 times during 22 days. The platelet count decreased in every case, with the lowest values reached at the third donation (day 5). The pre-donation count averaged 225 +/- 53 x 10(9)/l decreasing to 174 +/- 27 x 10(9)/l at the time of the 3rd donation then increasing by the 6th donation to 198 +/- 46 x 10(9)/l. The yield in the product decreased from 3.2 +/- 1.3 x 10(11) on day 1 to 2.6 +/- 0.8 x 10(11) for the third donation, returning thereafter to higher values. In spite of the expected and apparent stimulation of platelet production through feedback, the counts did not rebound above starting levels indicating a basic homeostatic mechanism. The donor WBC showed minimal changes during the study period, however there was a significant increase in the total number of lymphocytes by the 3rd procedure; this was corrected by the fifth procedure. The absolute number and ratio of T4 (helper) and T8 (suppressor) lymphocytes did not change.(ABSTRACT TRUNCATED AT 250 WORDS)