Nucleotides in lymphocytes of human subjects with zinc deficiency

Cell-mediated immunity in human subjects is affected adversely as a result of zinc deficiency. The mechanism by which a deficiency of zinc may affect lymphocyte proliferation and functions, is not well understood at present. Nucleoside phosphorylase (NPase), a purine catabolic pathway enzyme, is zinc dependent, and a congenital deficiency of this enzyme is known to affect adversely cell-mediated immunity. This effect has been related to an accumulation of toxic nucleotides in lymphocytes as a result of NPase deficiency. Inasmuch as the effect of zinc deficiency on the activity of NPase and the levels of nucleotides in human lymphocytes has not been previously reported, we assayed these parameters in human subjects with zinc deficiency before and after zinc supplementation. A mild deficiency of zinc was diagnosed in those having decreased zinc in two out of three cell lineages (less than 42 micrograms in granulocytes, less than 48 micrograms in lymphocytes, and less than 1.70 microgram in platelets, per 10(10) cells). In comparison with five subjects with sufficient zinc, six subjects with zinc deficiency showed a decrease in the activity of NPase (p = 0.01), an increase in adenosine diphosphate (ADP) level (p = 0.008), a decreased adenosine triphosphate (ATP)-to-ADP ratio (p = 0.0001), and an increase in both guanosine triphosphate (GTP) (p = 0.02) and deoxyadenosine triphosphate (dGTP) (p = 0.04 in the lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)