Benedict, Stephen HDunbar, Amanda Jo2021-02-272021-02-272019-12-312019http://dissertations.umi.com/ku:16827https://hdl.handle.net/1808/31485CD4+ T cells are essential for the effective functioning and appropriate regulation of the immune system. Antigen-naïve T cells require two distinct costimulatory signals to activate and differentiate into effector and memory T cells which can respond to antigen and direct the immune response. The first signal is through cognate antigen presented in major histocompatibility class II on an antigen-presenting cell binding to the T cell receptor. The second signal is the interaction of a costimulatory receptor on the T cell with a counter-receptor expressed on the antigen-presenting cell. This work focuses on the costimulatory receptors CD28, the classic T cell costimulatory molecule, and intercellular adhesion molecule-1 (ICAM-1). ICAM-1 functions in adhesion and extravasation during inflammation, and our lab has previously published that ICAM-1 can function as a T cell second signal for activation. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants which have been shown by many other investigators to have diverse effects on human health including the immune system. In the present work, we examined the consequences of exposure to two PAHs during naïve T cell costimulation. Bisphenol A, a widely used plasticizer and component of epoxy resins, was found to weakly promote naïve T cell proliferation during ICAM-1 costimulation but not in CD28 costimulation and did not perturb effector and memory cell differentiation in either costimulation. Pyrene, a product of incomplete combustion of organic materials, enhanced proliferation of naïve T cells in both ICAM-1 and CD28 costimulations and inhibited effector and memory cell differentiation in both costimulations. We also compared the differentiation of naïve T cells isolated using StemSep and EasySep naïve CD4+ T cell isolation kits upon being informed by StemCell, the manufacturer of the kits, that StemSep was being discontinued in favor of EasySep. In contrast to StemSep naïve T cells, with which we have published previously, EasySep-purified naïve T cells did not differentiate in response to costimulation through ICAM-1 or CD28 without addition of exogenous cytokines and had dramatically increased cell death. We showed that inclusion of CD25 antibody in the EasySep negative selection antibody cocktail was partially responsible for the observed loss of differentiation and viability. Likewise, the EasySep magnetic beads were partially at fault for observed failure to differentiate and loss of viability in EasySep naïve T cells. This result also suggested an important role for the CD25lo population of naïve T cells in the ability of the cells to differentiate, which is in keeping with the published literature.109 pagesenCopyright held by the author.ImmunologyImmunologyimmunomagnetic cell isolationnaive T cellspolycyclic aromatic hydrocarbonsT cell differentiationT cellsThesishttps://orcid.org/0000-0003-0523-6728openAccess