Joseph Kaplan

Zinc May Regulate Serum Leptin Concentrations in Humans

OBJECTIVE Leptin, the product of the ob gene, plays a key role in a feedback loop that maintains energy balance by signaling the state of energy stores to the brain and by influencing the regulation of appetite and energy metabolism. Zinc also plays an important role in appetite regulation. Thus, we evaluated the relationship between zinc status and the leptin system in humans. METHODS We studied nine healthy men with marginal zinc deficiency, induced by dietary means, before and after zinc supplementation. RESULTS Zinc restriction decreased leptin levels while zinc supplementation of zinc-depleted subjects increased circulating leptin levels. In addition, zinc supplementation increased IL-2 and TNF-alpha production that could be responsible for the observed increase in leptin concentrations. CONCLUSIONS Zinc may influence serum leptin levels, possibly by increasing the production of IL-2 and TNF-alpha.

Effect of Zinc Supplementation on Incidence of Infections and Hospital Admissions in Sickle Cell Disease (SCD)

Zinc deficiency is a common nutritional problem in adult sickle‐cell disease (SCD) patients. Hyperzincuria and increased requirement of zinc due to continued hemolysis in SCD are probable bases for zinc deficiency in these patients. Zinc deficiency affects adversely T‐helper1 (TH1) functions and cell mediated immunity and interleukin (IL)‐2 production is decreased in zinc deficient subjects. We hypothesized that zinc supplementation will improve T‐helper1 function and decrease incidence of infections in patients with SCD. We tested this hypothesis in 32 SCD subjects who were divided in three groups (Grs A, B, and C). Grs A (n = 11) and B (n = 10) were zinc deficient based on cellular zinc criteria and Gr C (n = 11) were zinc sufficient. Gr A subjects were observed for 1 year (baseline), following which they received zinc acetate (50 to 75 mg of elemental zinc orally daily) for 3 years. Gr B subjects were observed for 1 year (baseline), following which they received placebo for 1 year and then switched to zinc supplementation (50 to 75 mg of elemental zinc orally daily) for 2 years. Gr C subjects did not receive any intervention inasmuch as they were zinc sufficient. Prolonged zinc supplementation resulted in an increase in lymphocyte and granulocyte zinc (P = 0.0001), and an increase in interleukin‐2 production (P = 0.0001), decreased incidence of documented bacteriologically positive infections (P = 0.0026), decreased number of hospitalizations and decreased number of vaso‐occlusive pain crisis (P = 0.0001). The predominant pathogens isolated were staphylococci and streptococci involving the respiratory tract and aerobic gram‐negative bacteria, particularly Escherichia coli, involving the urinary tract. Further confirmation of our observations will require prospective studies of zinc supplementation in a larger number of SCD patients. Am. J. Hematol. 61:194–202, 1999.

Nutritional and Zinc Status of Head and Neck Cancer Patients: An Interpretive Review

In this review, we provide evidence based on our studies, for zinc deficiency and cell mediated immune disorders, and the effects of protein and zinc status on clinical morbidities in patients with head and neck cancer. We investigated subjects with newly diagnosed squamous cell carcinoma of the oral cavity, oropharynx, larynx, and hypopharynx. Patients with metastatic disease and with severe co-morbidity were excluded. Nutritional assessment included dietary history, body composition, and prognostic nutritional index (PNI) determination. Zinc status was determined by zinc assay in plasma, lymphocytes, and granulocytes. Pretreatment zinc status and nutritional status were correlated with clinical outcomes in 47 patients. Assessment of immune functions included production of TH1 and TH2 cytokines, T cell subpopulations and cutaneous delayed hypersensitivity reaction to common antigens. At baseline approximately 50% of our subjects were zinc-deficient based on cellular zinc criteria and had decreased production of TH1 cytokines but not TH2 cytokines, decreased NK cell lytic activity and decreased proportion of CD4+ CD45RA+ cells in the peripheral blood. The tumor size and overall stage of the disease correlated with baseline zinc status but not with PNI, alcohol intake, or smoking. Zinc deficiency was associated with increased unplanned hospitalizations. The disease-free interval was highest for the group which had both zinc sufficient and nutrition sufficient status. Zinc deficiency and cell mediated immune dysfunctions were frequently present in patients with head and neck cancer when seen initially. Zinc deficiency resulted in an imbalance of TH1 and TH2 functions. Zinc deficiency was associated with increased tumor size, overall stage of the cancer and increased unplanned hospitalizations. These observations have broad implications in the management of patients with head and neck cancer.

Influence of Maternal-Fetal Histocompatibility and MHC Zygosity on Maternal Microchimerism

To investigate the relationship between maternal-fetal histocompatibility and maternal microchimerism, we developed a sensitive quantitative PCR assay for the neomycin resistance gene (neoR), and, in a mouse model system, used neoR as a noninherited maternal allele marker of maternal cells to detect and quantitate maternal microchimerism in tissues of neoR−/− N2 backcross progeny of (neoR+/−)F1 females mated with neoR−/− males. Using this approach, we obtained evidence for the presence of chimeric maternal cells in the brain, spleen, and thymus of all weanling and adult mice so tested. The numbers of chimeric maternal cells present in the spleen did not differ significantly from those in the thymus regardless of age or maternal-fetal histocompatibility. At all ages, brain tissue had higher level of maternal microchimerism than lymphoid tissue in mice MHC identical with their mothers, but the levels were similar in mice MHC disparate with their mothers. The levels of chimeric maternal cells in both brain and lymphoid tissue of mice with homozygous syngenicity and maternal allogenicity were similar, and tended to be higher than tissue-specific levels in mice with either combined maternal-fetal allogenicity or heterozygous syngenicity. Thus, MHC homozygous progeny had higher levels of maternal microchimerism than MHC heterozygous progeny. We conclude that normal mice possess small numbers of maternal cells in spleen, thymus, brain, and probably most other tissues, and that maternal-fetal histocompatibility influences the levels of these cells by mechanisms related to MHC zygosity of the progeny.

Decreased expression of CD73 (ecto-5′-nucleotidase) in the CD8+ subset is associated with zinc deficiency in human patients

We used flow cytometry to observe the changes in T cell populations resulting from zinc deficiency in subjects with sickle cell anemia (SCA) and in healthy human volunteers without SCA. Zinc deficiency was associated with significant decreases in cellular zinc concentration, CD4+/CD8+ ratio, and percentage of CD73+ cells in the CD8+ population. The decrease in the percentage of CD73+ cells in the CD8+ subset was significantly correlated with lymphocyte zinc concentration and was accompanied by essentially no change in the percentage of CD11b+ cells in the CD8+ subset. Daily oral zinc supplementation in nine zinc-deficient human volunteers (25 mg elemental zinc) and in seven zinc-deficient SCA subjects (50 mg elemental zinc) resulted in increases in the absolute lymphocyte count and significant increases in the CD4+/CD8+ ratio and in the percentage of CD73+ cells in the CD8+ subset. In zinc-supplemented subjects, the increase in the percentage of CD73+ cells was accompanied by a significant decrease in the percentage of CD11b+ cells in the CD8+ subset. Changes in the CD4+/CD8+ and CD73+/CD11b- cell ratios in the CD8+ subset after treatment may provide a useful diagnostic criterion for zinc deficiency in humans.

Human T lymphocytes form rosettes with autologous and allogeneic human red blood cells

Abstract Human lymphocytes bind untreated human erythrocytes to form rosettes. The rosettes are highly unstable at temperatures greater than 4°C. Rosette formation occurs with autologous, as well as allogeneic, erythrocytes. More rosette formation occurs with thymocytes than peripheral blood lymphocytes. Cells from T cell lines, but not B cell lines, form rosettes. Rosette forming cells lack surface immunoglobulin. Therefore, binding of human erythrocytes, like binding of sheep erythrocytes, appears to be a property of human T lymphocytes.

Hemogen is a novel nuclear factor specifically expressed in mouse hematopoietic development and its human homologue EDAG maps to chromosome 9q22, a region containing breakpoints of hematological neoplasms.

We cloned a novel murine gene, designated Hemogen (hemopoietic gene), which was sequentially expressed in active hematopoietic sites and downregulated in the process of blood cell differentiation. Hemogen transcripts were specifically detected in blood islands, primitive blood cells and fetal liver during embryogenesis, and then remained in bone marrow and spleen in adult mice. Immunostaining demonstrated that Hemogen was a nuclear protein. We also identified a human homologue of Hemogen, named EDAG, which was mapped to chromosome 9q22, a leukemia breakpoint. Like Hemogen, EDAG exhibited specific expression in hematopoietic tissues and cells. Taken together, these data are consistent with Hemogen and EDAG playing an important role in hematopoietic development and neoplasms.

Circulating lymphocyte subsets in second- and third-trimester fetuses: Comparison with newborns and adults

OBJECTIVES Our objective was to compare the relative sizes of circulating lymphocyte subsets in fetuses, newborns, and adults. STUDY DESIGN Two-color flow cytometric analysis of lymphocyte cell surface markers was performed on blood from 64 fetuses, 22 newborns, and 67 normal adults. RESULTS All three groups had similar percentages of CD3+ total T cells, CD4+ helper T cells, CD8+ cytotoxic/suppressor T cells, and CD20+ B cells. Compared with adults, fetuses and newborns had markedly reduced percentages of CD57+ natural killer T cells and consistently increased percentages of CD5+CD20+ B cells. Most fetal and cord T and B lymphocytes expressed the activation marker CD38. CONCLUSIONS Similarities and age-dependent differences exist among fetal, newborn, and adult circulating lymphocyte subsets. Lymphocyte marker analysis may prove useful in the detection of fetal infection and other complications of gestation.

Human newborns are deficient in natural killer activity

The peripheral blood natural killer (NK) activity of newborns was found to be significantly less than that of adults. In mixing experiments newborn cells inhibited adult NK activity in only one of nine instances. Interferon treatmentin vitro increased newborn NK activity to an even greater degree than adult NK activity. These findings imply that diminished newborn NK activity is due not to inhibitory cells or lack of pre-NK cells but rather to deficientin vivo activation of pre-NK cells. This deficiency may be a major factor in the increased susceptibility of newborns to certain virus infections.

Spontaneous cytotoxicity of human lymphoblast cell lines mediated by normal peripheral blood lymphocytes. I. Differential susceptibility of T-versus B-cell lines.

Abstract Human lymphoblast cell lines of B- and T-cell origin have been tested for their ability to serve as targets in a 4-hr 51Cr release microcytotoxicity assay using normal human peripheral blood lymphocytes as effector cells. Cell lines of T-cell origin were susceptible to lysis in this assay by effector lymphocytes from all normal donors tested. Cell lines of B-cell origin were repeatably lysed by normal lymphocytes from some, but not all donors. Spontaneous cytotoxicity of B-cell lines, when observed, was also quantitatively less than was obtained using T-cell lines as targets. One cell line (RPMI-7666), of B-cell origin, was not susceptible to spontaneous cytotoxicity by almost all of the normal lymphocyte effectors tested. Lymphocytes from patients with acute lymphoblastic leukemia in remission were less capable of effecting lysis in this assay.