College of Agriculture & Natural Resources

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Subject: search.filters.subject.CD8+ T cells

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    Differential Expression of CD45RO and CD45RA in Bovine T Cells
    (MDPI, 2022-06-04) Kandel, Anmol; Li, Lei; Hada, Akanksha; Xiao, Zhengguo
    Effective vaccination induces immune memory to protect animals upon pathogen re-encounter. Despite contradictory reports, bovine memory T cells are identified based on two isoforms of CD45, expression of CD45RO plus exclusion of CD45RA. In this report, we contrasted CD45RA/RO expression on circulatory T cells with IFNγ and IL4 expression induced by a conventional method. To our surprise, 20% of cattle from an enclosed herd did not express CD45RO on T cells without any significant difference on CD45RA expression and IFNγ or IL4 induction. In CD45RO expressing cattle, CD45RA and CD45RO expressions excluded each other, with dominant CD45RO (>90%) expression on gamma delta (γδ) followed by CD4+ (60%) but significantly higher CD45RA expression on CD8+ T cells (about 80%). Importantly, more than 80% of CD45RO expressing CD4+ and CD8+ T cells failed to produce IFNγ and IL-4; however, within the cytokine inducing cells, CD4+ T cells highly expressed CD45RO but those within CD8+ T cells mostly expressed CD45RA. Hence, CD45RO is not ubiquitously expressed in cattle, and rather than with memory phenotype, CD45RA/RO expression are more associated with distinct T cell subtypes.
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    CTL-derived exosomes enhance the activation of CTLs stimulated by low affinity peptides
    (2018) Wu, Shu-Wei; Xiao, Zhengguo; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Cytotoxic T cell (CTL) is the key to induce an effective immune response against infections caused by intracellular pathogens, such as virus and cancer. CTLs with low affinity can induce and maintain a substantial population during an adaptive immune response, although CTLs with a highest-affinity receive competitive activation signals. Low-affinity CTLs are important to induce effector response and maintain a diverse memory repertoire. However, the mechanism of generating and maintaining the expansion of lower affinity CTLs is still unknown. Here, we showed that the presence of exosome (Exo) enhanced the CTL survival and increased the cell proliferation especially in CTLs treated with the low-affinity peptide. Exo together with peptides also improved the production of IFN-γ and GZB. The exosomal stimulation in CTLs was relative to up-regulation of CD25 expression, which enhanced the IL-2 survival signals. Moreover, Exo derived from an early stage of activation had a similar but weaker function comparing with Exo derived from a late stage of activation in activating CTLs. This study identified the important role of the exosome derived from CTLs stimulated by the highest-affinity peptide in activating the naïve T cells stimulated by the low-affinity peptide.