Spontaneous and antibody-dependent cell-mediated cytotoxicity by human T cell subpopulations

Subpopulations of human T lymphocytes. IX. Imbalance of T cell subpopulations in patients with progressive systemic sclerosis

Peripheral blood lymphocytes from twenty patients with progressive systemic sclerosis (PSS) were analysed for the numbers and proportions of B lymphocytes possessing surface immunoglobulin, cells with Fc receptors, T cella and T cells with receptors for IgM (T mu) or IgG (T gamma). In patients with PSS, B cells and lymphocytes with Fc receptors were comparable in both numbers and proportions to those of the control group. Circulating T lymphocytes were significantly fewer in the patient group. T mu cells were decreased and T gamma cells increased, resulting in lower T mu/T gamma ratios as compared to controls. This study demonstrates a profound imbalance between T mu and T gamma cells (containing a population of helper or suppressor cells, respectively). These results are discussed in relation to immunodeficiencies observed in patients with PSS.

Separation of human T lymphocyte subpopulations (Tmu, Tgamma) by density gradient electrophoresis

Purified human peripheral blood T lymphocytes were fractionated by density gradient electrophoresis on the basis of their surface charge. The high mobility cell fractions were found to be enriched in T cells having receptors for IgM (Tmu cells) with only minor proportions of T cells having receptors for IgG (Tgamma cells). In contrast, the low mobility cell fractions were enriched in Tgamma cells with very low numbers of contaminating Tmu cells. Both populations were of higher mobility than human peripheral blood B lymphocytes. High-affinity sheep erythrocyte resette-forming cells (E-RFC) were relatively enriched in the high and intermediate mobility fractions and appear to include the Tmu cells and the T cells without receptors for IgG or IgM (Tvarphi). The low affinity E-RFC were found only in the lower mobility fractions that included the Tgamma cell population. A direct correlation was observed between the number of Tgamma lymphocytes and the low affinity E-RFC in all the fractions. The separated cell fractions were treated in vitro with different concentrations of concanavalin A (Con A) and examined for the numbers of Tmu and Tgamma cells. Low concentrations of Con A (2.5 mug/ml) significantly increased the number of Tmu cells, whereas high concentrations of Con A (20 mug/ml and 40 mug/ml) markedly reduced the number of Tmu cells and increased the number of Tgamma cells. Furthermore, all fractions (both Tmu and Tgamma cell enriched) responded by proliferation to Con A, whereas only the high and intermediate mobility fractions (enriched in Tmu cells) responded to phytohemagglutinin. Fractions enriched in Tgamma cells responded very poorly to phytohemagglutinin. This method provides another technique for separating human Tmu- and Tgamma-enriched lymphocyte subpopulations and does not modulate the Fc receptors of the cells, in contrast to the rosetting techniques currently in use for the separation of these lymphocytes.

Impairment of cell-mediated immunity functions by dietary zinc deficiency in mice

Several immunologic features were analyzed in mice on a zinc-deficient diet [Zn(-)], in mice pair-fed a diet containing zinc [Zn(+)], in mice fed a Zn(+) diet ad lib, and in mice fed laboratory chow ad lib. When placed on a Zn(-) diet, 6- to 8-week-old A/Jax, C57BL/Ks, and CBA/H mice showed loss of body weight, low lymphoid tissue weight, and profound involution of the thymus within 4-8 weeks after initiation of the regimen. Approximately 50% of the mice on the Zn(-) diet developed severe acrodermatitis enteropathica (lesions on tail and paws) and diarrhea. Pair-fed mice on the Zn(+) diet did not show any of these symptoms. Mice on the Zn(-) diet showed the following immune deficiencies: (i) depressed plaque-forming cells against sheep erythrocytes after in vivo immunization; (ii) depressed T killer cell activity against EL-4 tumor cells after in vivo immunization; and (iii) low natural killer cell activity. However, antibody-dependent cell-mediated cytotoxicity against chicken erythrocytes was normal in the mice on the Zn(-) diet. Deficiency of T killer cell activity was not observed when immunization with EL-4 allogeneic lymphoma cells was carried out in vitro. Progressive loss of relative and absolute number of Thy 1.2+ cells and a proportionate relative increase in cells bearing Fc receptors was seen in spleen and lymph nodes of Zn(-) animals. It appears that zinc is an essential element for maintenance of normal T cell and other immune functions in vivo.