Metal(loid) levels in biological matrices from human populations exposed to mining contamination--Panasqueira Mine (Portugal).

Mining activities may affect the health of miners and communities living near mining sites, and these health effects may persist even when the mine is abandoned. During mining processes various toxic wastes are produced and released into the surrounding environment, resulting in contamination of air, drinking water, rivers, plants, and soils. In a geochemical sampling campaign undertaken in the Panasqueira Mine area of central Portugal, an anomalous distribution of several metals and arsenic (As) was identified in various environmental media. Several potentially harmful elements, including As, cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se), were quantified in blood, urine, hair, and nails (toe and finger) from a group of individuals living near the Panasqueira Mine who were environmentally and occupationally exposed. A group with similar demographic characteristics without known exposure to mining activities was also compared. Genotoxicity was evaluated by means of T-cell receptor (TCR) mutation assay, and percentages of different lymphocyte subsets were selected as immunotoxicity biomarkers. Inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis showed elevated levels of As, Cd, Cr, Mn, and Pb in all biological samples taken from populations living close to the mine compared to controls. Genotoxic and immunotoxic differences were also observed. The results provide evidence of an elevated potential risk to the health of populations, with environmental and occupational exposures resulting from mining activities. Further, the results emphasize the need to implement preventive measures, remediation, and rehabilitation plans for the region.

The T-cell receptor Vbeta gene repertoire and clonal expansion from peripheral blood T cells in benzene-exposed workers in China.

The toxicity of benzene to lymphocytes is well known; however, little is known about the variety of T-cells that are rearranged after benzene exposure. In order to further understand the relative toxicity of benzene on T-cells, we investigated the features of the complementarity determining region 3 (CDR3) of T cells from benzene exposed workers. CDR3 of the T-cell receptor variable beta-chain (TCRVbeta) subfamily genes were amplified using reverse transcriptase-polymerase chain reaction. The polymerase chain reaction products were further subjected to genescan analysis to evaluate the clonality of T cells. Results revealed 2-12 Vbeta subfamilies identified in 16 benzene-exposed workers. The number of detectable Vbeta subfamilies present in the benzene-exposed group was significantly lower than in the control group (p<0.05). The most frequently used Vbeta genes were Vbeta3, Vbeta21, Vbeta6, and Vbeta16. We observed a skewed distribution and clonal expansion of TCR Vbeta subfamilies in benzene-exposed workers.

Therapeutic blockade of TCR signal transduction and co-stimulation in autoimmune disease.

Autoimmune diseases are initiated and maintained by presentation of self antigen through complex interactions between different cells of the immune system. In most autoimmune disorders, autoantigen-specific responses are induced by the activation of specific T cells with self peptides displayed on activated antigen presenting cells (APCs). These T cells may then activate and drive B cell responses that either initiate or contribute to chronic disease pathogenesis. In order to activate the T cell, two signals are required: T cell receptor (TCR) engagement by autoantigen presented in the context of self MHC class II and costimulation (CD28-CD80/CD86 interactions). Feedback must also be provided to the APC through MHC class II engagement by the TCR and through costimulatory events controlling T cell differentiation and effector function (CD154-CD40 interactions, among others). With this in mind, numerous strategies have been developed to block the engagement and activation of self-reactive cells. We review and discuss recent progress in understanding the efficacy and underlying molecular mechanisms of three separate immunotherapeutic strategies targeting the TCR and costimulatory molecules: i) blocking TCR signaling (using non-mitogenic anti-CD3 monoclonal antibody); ii) blocking CD28 costimulation (anti-B7 monoclonal antibody blockade); and iii) blocking CD40 engagement on APCs (anti-CD154 monoclonal antibody blockade).

Longitudinal analysis of T-cell receptor gene use by CD8(+) T cells in early human immunodeficiency virus infection in patients receiving highly active antiretroviral therapy.

The effects of early antiretroviral therapy on the peripheral CD8(+) T-cell population were assessed by sequentially determining the T-cell receptor (TCR) repertoire complexity in a cohort of 15 individuals recently diagnosed with human immunodeficiency virus infection. Analysis was based on quantitative TCR variable B gene (TCRBV) usage and complementary-determining region 3 length assessment. Repertories were assessed at baseline and at weeks 2, 4, 12, 24, and 72 after initiation of therapy. Early administration of highly active antiretroviral therapy has a positive effect on the preservation and homeostasis of the CD8(+) cell repertoire. Nevertheless, differences from average baseline and control TCR profiles and initial development of repertoire perturbations were observed. The findings suggest that additional therapeutic protocols will be required during primary infection to significantly prevent long-term erosion of the T-cell-mediated immune response.

Somatic mutations at the T-cell antigen receptor in antineoplastic drug-exposed populations: comparison with sister chromatid exchange frequency.

OBJECTIVE: The objective of this study was to assess the genetic effect of occupational exposure to antineoplastic agents. METHOD: The influence of occupational handling of cytotoxic drugs was investigated by monitoring the frequency of sister chromatid exchanges (SCE), the percentage of cells with high frequencies of SCE (high-frequency cells, HFC), and the frequency of somatic mutation at the T-cell receptor (TCR) locus in mononuclear cells of exposed hospital nurses. These parameters were also measured in healthy donors and in cancer patients at the time of the diagnosis and following the administration of high doses of cytotoxic drugs requiring stem cell support. RESULTS: Our results show that (a) SCE and HFC values in occupationally exposed nurses do not differ from controls, (b) patients with newly diagnosed cancer or following chemotherapy show a number of SCE comparable to those of healthy donors, but a significantly different percentage of HFC, (c) cigarette smokers of all categories studied show higher frequencies of SCE and HFC as compared to nonsmokers, but the differences are not statistically significant, (d) the mutation frequency at the TCR locus in oncology nurses is higher, but not significantly different from the frequency in the control group, and (e) the increase of mutation frequency is statistically significant and seems to be dose dependent in patients treated with high-dose chemotherapy. CONCLUSIONS: Our data suggest that SCE frequency and HFC percentage are not reliable indicators of exposure to possible mutagenic/carcinogenic effects of antineoplastic drugs; on the contrary, our observations indicate that anticancer therapy induces somatic mutations at the TCR locus and suggest an association between exposure to cytotoxic agents and the increase in somatic mutations.