Patients with bronchogenic carcinoma often have low serum zinc concentrations and sometimes have markedly elevated renal zinc losses. Since normal zinc metabolism is critical for the proper function of T lymphocytes and natural killer cells, the effect of zinc status on T cell phytohemagglutinin response and peripheral blood lymphocyte natural killer cell activity was studied in patients with lung cancer. Mean (± SEM) serum zinc concentration in 75 patients with cancer was 67.4 ± 2.2 μg/dl versus 96.0 ± 8.0 μg/dl for normal subjects. Patients with low serum zinc levels (less than 70 μg/dl) had significantly higher urine zinc excretion than patients with normal serum zinc levels (1,385 ± 240 μg per 24 hours versus 392 ± 107 μg per 24 hours) (p <0.001). This pattern of zinc concentrations (i.e., low serum zinc in combination with high urine zinc) is typical of patients with mild zinc deficiency, and suggests that a mild chronic zinc deficiency state was present in some of these patients. When lymphocyte data were analyzed according to serum zinc concentrations and urinary zinc excretion, low serum zinc concentration and high urine zinc excretion both correlated with depressed T cell phytohemagglutinin response (p <0.005 and p <0.001, respectively). For instance, mean maximal phytohemagglutinin response in patients with urinary zinc excretion of more than 700 μg per 24 hours was 22,132 ± 3,201 cpm (n = 14) compared with 68,130 ± 6,850 cpm for patients with normal zinc excretion (n = 7). Peripheral blood lymphocyte natural killer cell activity did not correlate with either serum or urine zinc values. Oral zinc sulfate (220 mg, three times daily for six weeks) was then administered to patients with hyperzincuria (mean = 992 μg per 24 hours). Zinc-supplemented patients had normalization of T cell phytohemagglutinin response after zinc therapy, whereas control patients demonstrated continued T cell dysfunction. Natural killer cell activity did not change in either group during the study period. These data suggest that a mild subclinical zinc deficiency state may exist in some patients with lung cancer and may be an important cause of abnormal T cell function. Furthermore, zinc supplementation may be useful to improve lymphocyte function in selected patients. Whether zinc supplementation would alter the course of the disease or the patient's prognosis is presently unknown.
Bibliographical noteFunding Information:
From the Sections of Gastroenterology matology/Oncology and the Neuroendocrine search Laboratory, Veterans Administration Medical Center and the University of Minnesota, Minneapolis, Minnesota, and the Section of Gastroenterology, University of Kentucky and Veterans Administration Medical Center, Lexington, Kentucky. This work was supported in part by funds from the Veterans Administration Merit Review Funds, a grant from the Minnesota Medical Foundation, and &ant CA 20365 from the National Institutes of Health. Requests for reprints should be addressed to Dr. John I. Allen, Gastroenterology Section (11 lD), Veterans Administration Medical Center, 54th Street and 48th Avenue South, Minneapolis, Minnesota 55417. Manuscript accepted December 6, 1984.