An approach to the restoration of T cell function in a purine nucleoside phosphorylase deficient patient.

A patient with a selective impairment of T cell-dependent immunity based on a purine nucleoside phosphorylase (PNP) deficiency has been treated with transfusions of irradiated erythrocytes and plasma. After each transfusion with PNP-containing erythrocytes a decrease in accumulated nucleosides and their deoxy compounds was observed, whereas uric acid excretion and serum uric acid increased. Lymphocyte counts increased transiently after each erythrocyte and plasma infusion and a partial restoration of T cell-dependent immunity was gradually attained. The pattern of restoration was reminiscent of the immunological reconstitution seen in patients with severe combined immunodeficiencies treated with bone marrow transplantation. Amelioration of T cell-dependent immunity was shown to be related to the metabolic changes. On the basis of the presumed mechanism of lymphocyte intoxication and consequently starvation of intracellular DNA precursors, deoxycytidine was given orally. This did not lead to further improvement in immunological function. However, partial restoration of immunological disturbances in PNP deficiency can be attained by erythrocyte transfusions and evidence is presented that additional pharmacological approaches are possible.