Lymphocyte 5'-nucleotidase in primary hypogammaglobulinaemia and cord blood.

The 5'-nucleotidase (5'-N) deficiency on circulating mononuclear cells of patients with 'common variable' hypogammaglobulinaemia (CV-H) was shown to be the result of one or more of three factors: reduced T cell 5'-N activity, a reduced percentage of circulating B cells, and a low B cell 5'-N activity. A lack of circulating B lymphocytes, together with a low T cell 5'-N activity in some cases, was found to be responsible for the deficiency of lymphocyte 5'-N in patients with X-linked hypogammaglobulinaemia (X-H). The low levels of 5'-N activity in CV-H and X-H patients were not due to abnormal compartmentalization of the enzyme, altered enzyme kinetics, or the presence of a regulatory factor. Cord Blood B and T cells have a lower 5'-N activity than adult lymphocytes. The patient and cord blood data are discussed in relation to the stage of cellular maturity.