Katherine Chitty, Nico Herndon, Claire Sibold
Faculty Sponsor: Sophia Sarafova
Previous research at Davidson College has identified the laboratory mice strain in our facility, B10.A, having a fewer number of CD4 cells than CD8cells, which results in an inverted CD4:CD8 ratio in the peripheral lymphoid organs compared to the parental B10 mouse strain. Tregs are a sub-class of the CD4+ cell lineage, yet they serve a very different function than the conventional helper CD4+ T cells: Tregs regulate effector T cells in periphery, preventing autoimmune responses and modulating cytokine signaling. Given the unique nature of the Treg subclass, we are interested in looking at whether there is a difference in total number and frequency of Treg cells in mice with inverted ratios, B10.A mice. It is possible that we will observe a greater reduction in Treg cells compared to conventional CD4+, we would conclude that Treg cells are one of the CD4+ subpopulations affected most by the B10.A environment. Alternatively, if we observe a lesser reduction in Treg cells compared to conventional CD4+, we would conclude that Treg cells are not affected by the B10.A environment. Additionally, we would conjecture that they may be involved in suppressing CD4+ effector populations by over-regulation of cytokine levels. Finally, if both populations decline by the same proportion, we can conclude that the effect causing dysregulation of CD4+ cells may be targeting a receptor that is common to Treg and other types of CD4+ cells. This would delimit the possible options for this receptor/signal. In order to distinguish between these possibilities, we compared the number and frequencies of conventional CD4+ and Tregs from lymph nodes of both mouse strains. Tregs can be distinguished from conventional CD4+ cells by the expression of CD25 on the cell surface and FoxP3 intracellularly. We used these properties for our immunostaining and flow cytometry experimental design. In this poster, we present our findings about the number and frequency of Tregs in B10 and B10.A mice.