No abstract

Measurements have been made of the absolute T‐cell loss experienced by normal donors undergoing three methods of pheresis used for the preparation of platelets and/or granulocytes for transfusion. Filtration leukapheresis was associated with a mean loss per donation of 1.7×108 T cells. The technique of intermittent flow centrifugation platelet pheresis resulted in a mean loss per donation of 3 × 109 T cells. When this latter technique was utilized for leukapheresis, with hydroxyethyl starch and prednisone taken 12 h before the donation, the mean loss per donation was 3.9×109 T cells. When an intravenous dose of dexamethasone at the commencement of the procedure was used instead of prednisone for leukapheresis by intermittent flow centrifugation, the mean cell loss per donation was 2.2×109 T cells. We have examined the immediate effects of these procedures on circulating T lymphocytes and their responsiveness to mitogens. The only change of significance was an increased responsiveness to phytohemagglutinin after leukapheresis of the lymphocytes of those donors who had received prednisone. Replacement of T cells appears to be inefficient in adult life and thus functionally important numbers of T lymphocytes may be removed by repeated pheresis procedures. Careful examination of the potential immunological and clinical consequences of repeated pheresis appears warranted.

Measurements have been made of the absolute T-cell loss experienced by normal donors undergoing three methods of pheresis used for the preparation of platelets and/or granulocytes for transfusion. Filtration leukapheresis was associated with a mean loss per donation of 1.7 x 10^8 T cells. The technique of intermittent flow centrifugation platelet pheresis resulted in a mean loss per donation of 3 x 109 T cells. When this latter technique was utilized for leukapheresis, with hydroxyethyl starch and prednisone taken 12 h before the donation, the mean loss per donation was 3.9 x 10^9 T cells. When an intravenous dose of dexamethasone at the commencement of the procedure was used instead of prednisone for leukapheresis by intermittent flow centrifugation, the mean cell loss per donation was 2.2 x 10^9 T cells. We have examined the immediate effects of these procedures on circulating T lymphocytes and their responsiveness to mitogens. The only change of significance was an increased responsiveness to phytohemagglutinin after leukapheresis of the lymphocytes of those donors who had received prednisone. Replacement of T cells appears to be inefficient in adult life and thus functionally important numbers of T lymphocytes may be removed by repeated pheresis procedures. Careful examination of the potential immunological and clinical consequences of repeated pheresis appears warranted.