Gabriel Fernandes

Circulating thymic hormone levels in zinc deficiency

Abstract The effect of zinc deficiency (Zn − ) on the circulating thymic hormone (FTS) levels in A/J mice was studied. After 3 weeks of feeding the mice a Zn − diet, FTS levels were markedly reduced and after 17 weeks, FTS was undetectable. By contrast, the zinc-supplemented (Zn + ) group seemed to maintain FTS levels better than the normal diet group with aging. On the other hand, spleen spontaneous rosette-forming cells (sRFC) were studied for their azathioprine (AZ) sensitivity in A/J mice on different diets. The Zn − mice had fewer sRFC than did the normally fed or Zn + mice. The role of zinc in controlling levels of FTS and thus thymic function is discussed.

Natural killing and antibody-dependent cytotoxicity by lymphocyte subpopulations in young and aging humans

Natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) were examined in the peripheral blood lymphocytes and their major subpopulations from young and aging subjects. Monocyte-depleted unseparated lymphocyte-mediated NK activity (against cells of K-562) and ADCC (against IgG-coated chicken erythrocytes) were comparable between young and aging subjects. Similarly no significant difference was observed in T cell-mediated NK and ADCC and non-T cell-mediated ADCC between young and aging subjects. Non-T cell-mediated NK activity, however, was significantly (P<0.025) greater in aging humans compared to that of young subjects. When the data were analyzed according to gender, T cell-mediated ADCC in aging males was significantly (P<0.05) greater than that found in young males. No significant difference was observed between T-cell ADCC among young and aging females. T cell-mediated NK was comparable among young and aging males and young and aging females. Non-T cell-mediated NK as well as ADCC activity was significantly (P<0.025 or <0.05) greater in aging males compared to that in young males. Both non-T-cell NK and ADCC were comparable among young and aging females. This study demonstrates an increase in NK and ADCC activity in aging subjects that is primarily shared by males and not by females. No correlation was observed between the proportion of Tγ cells and T-cell NK or ADCC activity.

Multivariate analysis of T-cell functional defects and circulating serum factors in Hodgkin's disease.

A comprehensive immunologic and serologic analysis was performed on 31 untreated patients with Hodgkins disease. Immune evaluations stressed T‐cell functional activity and included traditional parameters (PHA responsiveness and delayed hypersensitivity skin reactivity), as well as newer functional assays (T‐cell colony formation, chemotaxis, spontaneous and antibody‐dependent cytotoxicity, and concanavalin A‐induced suppressor cell activity (CISA)). Serum factors included ferritin, prostaglandins, zinc, copper, immune complexes, and thymic hormone activity. Every patient exhibited at least one T‐cell or serum abnormality. The greatest percentage of patients exhibited T‐cell defects in chemotaxis (85%), colony formation (81%), and PHA reactivity (64%). Immune defects were more common with advanced disease but were not related to absolute T‐cell or monocyte count, skin test anergy, or abnormalities of Tμ/Tγ cell proportions. Linear relationships were identified among abnormalities in the three assays employing mononuclear cells (PHA, colony formation, CISA) which may have reflected the inhibitory influence of monocytes present in the mononuclear cell preparations. Low serum zinc correlated with marked impairment of T‐cell chemotaxis. Elevated prostaglandins were associated with high PHA reactivity and with depressed colony formation. Our results indicate that many complex factors, including intrinsic T‐cell defects, contribute to the impaired immunity associated with Hodgkins disease.

Effect of calorie restriction on the production and responsiveness to interleukin 2 in (NZB × NZW)F1 mice

Abstract Calorie restriction preserves the immunologic functions of the autoimmune prone B/W mice and prolongs their life. B/W mice fed normal calories were deficient in production of Interleukin 2 (IL-2) and in responses to exogenous IL-2 after 5 months of age. Calorie restriction leads to the preservation of IL-2 production in the spleen cells of these animals. Furthermore, these calorie-restricted mice responded vigorously to exogenous IL-2 in the thymocyte proliferation assay while mice fed a normal calorie diet lost much of the ability of their thymocytes to respond to IL-2. Whether calorie restriction in preserving the immune function of B/W mice involves IL-2 production and/or IL-2 response requires further analysis.

The differential sensitivity of T-Cell and B-Cell mitogenesis to in vitro zinc deficiency

Abstract The relative requirement for zinc in B-cell and T-cell mitogenesis was investigated utilizing a tritiated thymidine uptake assay. When ethylene diaminetetraacetate (EDTA) was added to the culture medium at concentrations less than 0.02 m M , B-cell mitogenesis, induced by lipopolysaccharide B (LPS), was not affected. However, T-cell mitogenesis, induced by either phytohemagglutinin P (PHA) or concanavalin A (Con A), was inhibited. When fetal calf serum (FCS) dialyzed against EDTA was used in the medium, B-cell mitogenesis was again unaffected, whereas T-cell mitogenesis was reduced by nearly one-half, even in the absence of EDTA in the medium. Cell viability was practically unaffected by the dialysis procedure. However, the addition of EDTA at concentrations of 0.01 to 0.05 m M reduced the percentage of viable cells by about one-third. Cell viability was reduced to practically zero at a concentration of 0.5 m M EDTA. The inhibitory effect of EDTA on Con A-stimulated mitogenesis was completely reversed by zinc, only partially reversed by nickel, and unaffected by either calcium or magnesium. Thus it appears that B-cell mitogenesis is not affected by zinc deficiency in vitro , whereas T-cell mitogenesis is substantially inhibited, indicating the requirement of zinc for T-cell function.

Immune function in fully allogeneic mouse bone marrow chimeras

Abstract Stable, long-lived, immunologically functional H-2 allogeneic chimeras, free of graft vs host disease, were established by reconstituting irradiated CBA J (H-2k) mice with C57BL 6 (H-2b) bone marrow, previously depleted of Thy 1+ cells with monoclonal anti-Thy 1.2 (mc-α-Thy 1.2) serum and complement (C). All lymph node cells of these chimeras expressed the donor H-2 phenotype, while a small, significant number of cells expressing host H-2 determinants were detectable in the spleens of the chimeras throughout the period of investigation. Skin graft rejection pattern, MLC, and CML responses of chimeric mice were normal against third-party targets, but reflected complete tolerance against donor and host determinants. NK activity against tumor cell targets was also normal. The host-like pattern of chimeric ADCC response against chicken red blood cells suggested the persistent activity of host macrophages. In contrast to the reduced primary PFC response against SRBC, the vigorous secondary response of the chimeras suggested that haplotype restrictions are not absolutely binding when there is an opportunity for prior learning.

Suppression of natural killer (NK) cell activity of spleen cells by thymocytes

The in vitro influence of thymus cells on natural killer cell activity of spleen cells against prelabeled target cells (YAC-I and RL♂I) has been studied in syngeneic as well as in allogeneic murine models. In mixing experiments to demonstrate suppression, total thymocytes have been found to have no effect on NK activity of syngeneic or allogeneic spleen cells. Among several thymocyte fractions separated by velocity sedimentation, a relatively faster sedimenting fraction showed remarkable suppression of NK activity by spleen cells against two target cells. The suppressive effect of this particular fraction on NK activity was demonstrated to be proportional to the cell dose. The suppressive function was resistant to irradiation at 1000 or 2000 rad administered in vitro and was not restricted by the major histocompatibility complex. Moreover, the thymocyte fraction which induced suppression was not sensitive to NK-mediated cytolysiś by syngeneic spleen cells. The suppression of NK cytolysis in vitro by certain subpopulations of thymocytes as observed in the present studies may be consistent with a role for the thymus in regulating NK activity in vivo.

Effect of zinc deficiency on autologous rosette-forming cells.

Abstract Ability to form autologous rosettes (A-rosettes) is characteristic of a certain population of immature T cells, present in the thymus of various species including man. In mice, few A-rosettes are normally found in peripheral blood and spleen but their number increases markedly in spleen following thymectomy. In our studies, A-rosette formation could be demonstrated to be significantly enhanced in the spleen of C57B1/Ks mice after the animals had been maintained 3, 6, and 8 weeks on a zinc-deficient diet (Zn − ) and to increase progressively with duration of feeding the Zn − diet. These changes were quickly reversed by feeding a normal diet containing zinc but could not be eliminated by complete adrenalectomy, a finding that ruled out their dependence on pituitary-adrenal as is function attributable to stress. Pair-fed controls and mice fed a zinc-supplemented diet ad libitum showed few A-rosettes, as expected.

Changes in macrophages and their functions with aging in c57bl/6j, akr/j and sjl/j mice.

Abstract Changes in phagocytosis, chemotaxis, and nonspecific esterase staining of peritoneal exudate mononuclear cells occurred with aging in B6, AKR/J, and SJL/J mice. Different patterns of change with aging were observed with each of these three parameters in each of the strains. In the long-lived B6 mice, a progressive increase with aging in all three parameters was seen. In AKR/J mice, progressive increase in phagocytosis and nonspecific esterase staining was observed but a decline of chemotaxis occurred with aging. In SJL/J mice, all three parameters were very low early in life and each showed a significant increment upon reaching the age when the characteristic malignant lymphoreticular disease occurs.

Sequential changes of thymocyte surface antigens with presence or absence of graft-vs-host reaction following allogeneic bone marrow transplantation

Abstract Lethally irradiated AKR mice were reconstituted with C57BL/6 bone marrow cells. Though the allogeneic marrow transplantation protected AKR recipients from acute irradiation deaths, the mice given unmanipulated marrow developed severe GVHR disease, and 80% died within 50 days. The thymus and spleen from the recipient mice, following recovery of body weight between the 10th and 20th days, gradually involuted and became miniscule after Day 30. Thymocytes from recipients were found to be entirely of donor cell type by Day 15. Thereafter, however, as the graft versus host reaction (GVHR) developed, changes in sensitivity of the thymocytes to four different alloantisera directed toward donor histocompatibility antigens (H-2b, Thy 1.2, Lyt 1.2, and Lyt 2.2) were observed and these changes were associated with changes in antigen expression or quantity of Thy 1 antigens on the thymocytes. A different pattern of changes was observed in antigen expression on thymocytes in mice given B6 marrow cells that had been pretreated with anti-Thy 1 serum which prevented initiation of graft-vs-host disease and in the mice which received marrow not so treated and which regularly led to graft-vs-host disease. By contrast, the amount of H-2 antigen on the thymocytes from chimeras with or without GVHR was elevated equally. The mechanisms of these changes are discussed.