Environmental toxicants with the ability to directly or indirectly modify the cellular thiols of lymphocytes can initiate immune dysfunctions resulting in increased incidence of infectious diseases, cancer and/or autoimmune diseases. The majority of our analyses will employ T cells, the regulators of the immune system; however, we will also compare the thiol characteristics and sensitivities of T and B cells; furthermore, we will evaluate the thiol-related biochemical differences between mouse and human lymphocytes. Preliminary data suggests that these species have differential thiol characteristics. The ability of exogenous and endogenous thiols, thiol-blockers, oxidants and anti-oxidants, as well as irradiation, to alter the subcellular mechanisms necessary for the activation and growth of lymphocytes will be assessed. In order to accomplish this objective we first must evaluate some thiol characteristics key to the biochemical activation of lymphocytes. The lymphoid subsets have different thiol sensitivities which we believe are due, in part, to variances in their exofacial thiols. Biochemical and cellular/molecular biology technics will be utilized to assess the influences of thiol modulation at various levels within the cell (exofacial, transmembranal, cytosolic, and nuclear). Novel thiol reactive chemicals and antibodies will be used to probe these cellular domains. Various cDNA probes, monoclonal antibodies, and anti-sense oligonucleotides will be used to assess the regulation of the mRNA expression, protein expression (and distribution) and need for thiol modulation of cellular cysteinyl proteins believed to be involved in lymphocyte activation. Some specific proteins to be assayed include protein kinase C, phospholipase C, calmodulin, and ornithine decarboxylase as well as some proto-oncogenes (c-myc; c-fos). The homogenous nature of cloned T cells, T cell hybridomas, and T cell tumor lines will aid in the analysis of the thiol-related sensitivities and activities of the subsets. Subcellular differences between the T cell subsets and cell lines will be compared. Evaluation of some biochemical changes involved in the stimulation of the different types of T cells will aid in the assessment of differences between non-proliferating and rapidly proliferating T cells and the processes involved in modulating their activation. The mechanism(s) of cell injury and modulation of activation and growth by toxicants with thiol reactivities will be further defined by our analyses. In addition, information may be obtained on numerous diseases which concomitantly have aberrant immune functions and redox states such as AIDS, Bloom's Syndrome, Ataxia Telangiectasia and Down's Syndrome.
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