EFFECT OF RBC TRANSFUSIONS ON ADENOSINE DEAMINASE(ADA) DEFICIENT SEVERE COMBINED IMMUNODEFICIENCY(SCID)

Abstract

Previous work suggests that the immunological defect in ADA deficient SCID is mediated by increased lymphocyte nucleotides including ATP and cAMP. We attempted to improve this tmmunological deficit in a 10-month-old affected male by supplying the missing enzyme activity with RBC and plasma transfusions from normal donors. The child received 14 RBC and 4 plasma transfusions over a 14 month period. A 2-fold increase in blood lymphocytes occurred 10-12 days after transfusion (P<0.05), whereas the number of other leukocytes did not change. Incorporation of ³H-thymidine by phytohemagglutinin stimulated and unstimulated lymphocytes reached a maximum at 12-15 days (2-fold increase, P<0.05). Serum immunoglobulin concentrations increased to normal after 6 months of therapy, but specific antibodies and delayed hypersensitivity were undetected. Urinary adenine decreased after each transfusion and inversely correlated with ADA activity After the initial decrease in lymphocyte ATP (9671→4527 nm/10⁹ cells, P<0.05), the level increased rapidly during the following week. This could not be prevented by further transfusion during this period.

While certain immunologic functions may be improved by infusion of enzyme containing blood products into some ADA deficient patients, therapy in our patient produced only transient changes in purine metabolism and minimal immunologic reconstitution.