Reduced number and impaired function of circulating gamma delta T cells in patients with cutaneous primary melanoma.

We studied the peripheral representation, in vitro expansion, cytokine production, and cytotoxicity of gamma delta T lymphocytes from 23 patients with cutaneous primary melanoma and 28 healthy subjects. We demonstrated that the absolute number and the percentage of circulating gamma delta + T cells were significantly reduced in melanoma patients in comparison with healthy subjects. The decrease was due to a reduction of V delta 2 T cells, whereas the number of V delta 1 T cells was not affected. As a consequence, the V delta 2/V delta 1 ratio was inverted in melanoma patients. A lower percentage of gamma delta + T cells producing tumor necrosis factor-alpha or interferon-gamma was found in melanoma patients. After a 10 d in vitro culture, both the percentage and the expansion index of gamma delta T cells, and in particular of V delta 2 subset, were significantly reduced in melanoma patients in comparison with healthy subjects. The cytotoxicity of sorted gamma delta T cells against tumor cell lines and the percentage of gamma delta T cells producing perforins were preserved in melanoma patients. The numerical and functional impairment of gamma delta T cells could contribute to the inadequate immune response found in melanoma patients and offers the potentiality for the planning of new approaches of immune therapy of malignant melanoma.

Phenotype, antigen-presenting capacity, and migration of antigen-presenting cells in young and old age.

In the present paper, we investigated whether the phenotype, the antigen-presenting capacity, and the migration of antigen-presenting cells (APCs), are affected by the aging process. APCs were obtained incubating peritoneal monocyte-macrophage cells with granulocyte-macrophage colony-stimulating factor (GM-CSF) (immature APCs) or GM-CSF and IFNgamma (mature APCs). Phenotypically, after 8 days incubation, APCs cultures were composed of CD11c and Mac-3 cells, with a similar representation, both in young and old mice. The absolute number and the expression of MHC I and II, CD80, and CD86 both on immature and mature APCs were not significantly different in young and old mice. APCs from old mice induced similar lymphocyte proliferative responses but lower lymphocyte cytotoxicity and a reduced number of CD8(+) T cells producing IFNgamma in comparison with APCs from young animals. Lymphocyte responses were antigen-specific, since TS/A pulsed APCs induced lymphocyte cytotoxicity against TS/A but not against syngeneic TUBO tumor cells. The low expression of the mRNA for the migratory CCR7 chemokine receptor present in immature APCs from old mice was greatly increased in mature APCs up to the levels found in APCs from young animals. The in vivo migration of APCs was higher in old than in young mice. These results demonstrate that some alterations in APCs function are present in aging, suggesting that an increased migratory capacity of old APCs may be required to balance their reduced antigen presentation to cytotoxic lymphocytes.

Age-dependent effects of repeated immunization with a first generation adenovirus vector on the immune response and transgene expression in young and old rats.

We evaluated the kinetics of transgene expression and humoral and cellular immune responses against viral antigens and the product of the reporter gene LacZ in young (4 months) and old (20 months) Wistar rats. Animals received the intramuscular injection of a recombinant E1-deleted human type 5 adenovirus encoding beta-gal (Ad-LacZ) on days 0 and 30. The transgene expression evaluated on day 2 after infection revealed a significantly higher beta-gal activity in young than in old animals (1.9-fold increase, p<0.05). beta-gal expression decreased on day 6, and on day 15 transgene activity was undetectable in muscles from both groups. Ad-LacZ inoculation was repeated on day 30 in both animal groups. However, after the second adenovirus administration, no increase in beta-gal activity was observed. Humoral and cellular immune responses, evaluated after the first and second Ad-LacZ injection, developed with similar kinetics in young and old rats. In particular, the antigen specific antibodies were able to kill adenovirus-infected tumor cells in both complement-dependent cytotoxicity (CDC) and antibody-mediated cell-dependent cytotoxicity (ADCC) assays. Lymphocyte proliferation in response to the in vitro stimulation with specific antigens was significantly lower in old than in young animals whereas no difference was found in cytotoxic T lymphocyte activity against adenovirus-infected tumor cells. Our results demonstrate that repeated immunization with AdCMV.LacZ induces minor age-related differences in immune response which precludes gene expression both in young and old animals.

Numerical and functional alterations of circulating gammadelta T lymphocytes in aged people and centenarians.

The aim of this study was to evaluate the peripheral representation, in vitro expansion, cytokine production, and cytotoxicity of gammadelta T lymphocytes from 104 healthy subjects ranging in age from 19 to 103 years. We demonstrated that the absolute number of circulating gammadelta(+) T cells was reduced significantly in old people and centenarians in comparison with young subjects as a consequence of the age-related decreased lymphocyte number. The decrease was a result of an age-dependent reduction of Vdelta2 T cells, whereas the absolute number of Vdelta1 T cells was unaffected by age. As a consequence, the Vdelta2/Vdelta1 ratio was inverted in old subjects and centenarians. A higher percentage of gammadelta(+) T cells producing tumor necrosis factor alpha was found in old donors and centenarians, whereas no age-related difference was observed in interferon -gamma production. After a 10-day in vitro expansion, a twofold lower expansion index of gammadelta T cells, and particularly of a Vdelta2, but not of a Vdelta1 subset, was found in old people and centenarians in comparison with young subjects. The cytotoxicity of sorted gammadelta T cells was preserved in old people and centenarians. The alteration of gammadelta T cells could contribute to the age-related derangement of T cell-mediated, adoptive responses and may represent a new characteristic of immunosenescence.

Reactive oxygen species modulate Zn(2+)-induced apoptosis in cancer cells.

Some recent evidence has suggested a protective role of zinc against cancer. The mechanism by which zinc exerts this action has not been defined and, in particular, it has not been clarified whether zinc may directly act on cancer cells and the molecular mechanisms involved in this effect. In this study, we examined the in vitro effect of zinc on the apoptosis of mouse TS/A mammary adenocarcinoma cells, studying the zinc-dependent modulation of the intracellular levels of reactive oxygen species (ROS) and of p53 and Fas/Fas ligand pathways. We showed that zinc concentrations ranging from 33.7 to 75 muM Zn(2+) induced apoptosis in mammary cancer cells. The apoptosis was associated with an increased production of intracellular ROS, and of p53 and Fas/Fas ligand mRNA and protein. Zn(2+) induced a faint metallothionein response in TS/A cells in comparison with mouse lymphocytes. The treatment of tumor cells with the antioxidant N-acetylcysteine was able to prevent Zn(2+)-induced apoptosis, as well as the increase of p53 and Fas ligand protein induced by zinc. The data demonstrate that zinc exerts a direct action on mammary cancer cells inducing ROS-mediated apoptosis and that the effect may be mediated by the ROS-dependent induction of p53 and Fas/Fas ligand.