693 RESPONSE TO ADENOSINE DEAMINASE (ADA) REPLACEMENT THERAPY IN A CHILD WITH SEVERE COMBINED IMMUNODEFICIENCY DISEASE (SCID) AND ADA DEFICIENCY

Abstract

A boy was diagnosed to have SCID at age 4½ mos. No thymic shadow, adenoidal tissue or skeletal anomalies were found on X-ray. IgG and IgM were markedly decreased. Lymphocyte response to phytohemagglutinin (PHA) revealed a stimulation index (SI) of 0.96 and candida, SK-SD and PPD skin tests were negative. Enzymatic assays for ADA showed only trace amounts in red cells, lymphocytes and granulocytes. Patient was treated with transfusions of irradiated frozen red cells and irradiated frozen plasma according to the method of Polmar, et al. Gradual clinical improvement occurred and he is now 18 mos old and clinically well. After starting therapy his immunoglobulins increased to above normal levels. However, in contrast to the patient reported by Polmar, et al, our patient still has no thymus by chest X-ray and his absolute numbers of lymphocytes have varied markedly, as have his % of T and B cells. Similarly, SI's in response to PHA, ConA, pokeweed and LPS have varied between 0-40% of normal. These variations have occurred in spite of a normal level of ADA in his red cells. No inverse correlation between the nucleotides and ADP levels was noted. These results indicate that replacement therapy has been beneficial clinically. However, because of the fluctuation in the immune responses, the role of replacement therapy with ADA is unclear and further studies are indicated.