CYTIDINE DEAMINASE DEFICIENCY AND IMMUNODEFICIENCY MORE THAN A COINCIDENCE ?: 155

Abstract

A 9 month-old boy, the fourth and the only surviving child of consanguineous parents of tunisian origin, was investigated for severe immunodeficiency associated with autoimmune anemia and thrombocytopenia. Increased serum immunoglobulin levels contrasted with an absence of antibody response after sensitization and blood T lymphocytes increased in number were incapable of proliferating normally in the presence of mitogens, antigens or of OKT3 antibody. Defective secretion of IL2 and of IFNrby patient's leukocytes was observed whatever the inducer used. Proliferative response as well as IFNr secretion were restored by incubation in the presence of exogenous IL2. Enzyme study disclosed a profound deficiency in cytidine deaminase (CDA) in the patient's lymphocytes (10-21-23 pmol.min−1.10−6 cells, normal value 130 ± 30, n = 39). Low values were found in the father (20-21) and the mother (18-55). Cytidine (100 μM) did reverse the inhibitory effect of pyrazofurin on parents' lymphocytes PHA-induced proliferation but not that of patient's lymphocytes. During a 6-months survey lymphocyte CDA activity of the patient, his father and mother rose to 63, 140 and 130 pmol.min−1.10−6 cells, respectively. The fact that CDA deficiency has been transitory in the parents rules out an hereditary enzymatic defect. Nevertheless, our results suggest that CDA activity should be systematically determined in immunodeficient patients.