Lymphocyte 5'-nucleotidase deficiency in hypogammaglobulinemia: Clinical characteristics

Abstract

Twelve patients with congenital agammaglobulinemia, 2 of 10 patients with selective IgA deficiency, and 4 of 15 patients with common variable immunodeficiency have reduced 5'-nucleotidase activity on lymphocyte plasma membranes. In congenital agammaglobulinemia and common variable immunodeficiency, enzyme-deficient patients have an early onset of immune dysfunction, low levels or an absence of circulating B-lymphocytes, and a positive family history of similar immunodeficiency. The enzyme deficiency involves peripheral E-rosette-forming lymphocytes, suggesting an abnormality of T-lymphocytes in these diseases. No systemic disorder of purine nucleotide degradation to uric acid is detectable in the enzyme-deficient patients. No direct relationship between 5'-nucleotidase activity and in vitro production of IgG is evident, since inhibition of the enzyme did not decrease IgG synthesis. At present the data do not allow a distinction between two hypotheses to explain the role of 5'-nucleotidase in hypogamma-globulinemia, that is, whether 5'-nucleotidase deficiency causes the immune dysfunction or is simply a marker for an intrinsic lymphocyte abnormality. However, this enzyme deficiency may provide a useful means of classifying disorders of immunoglobulin synthesis.