Kerry Zhue, Morgan Potter, Grant Kelleher
Faculty Sponsor: Sophia Sarafova
Research by Carico et. al., 2012 examining B10. A strain at Davidson’s conventional animal facility discovered that these mice have an inverted peripheral CD4:CD8 T cell ratio, less than one, as compared to the B10 strain that maintains a normal CD4:CD8 ratio bigger than one. Our class decided to investigate potential reasons for the inverted T cell ratio in the B10.A strain. It was proposed in Carico et. al. that one potential reason for the inverted CD4+/CD8+ ratio in T cells could bet that the strain has a reduced number of B cells, which serve as antigen presenting cells for CD4+ T cells. In addition, the B cells may have lower levels of MHC-II, the molecule necessary to present antigen to CD4+ T cells. The activation signals from B cells via MHC-II are important for the survival of CD4+ T cells. If CD4+ T cells are low in B10.A mice, we then hypothesize that the CD4:CD8 T cell ratio inversion will correlate with lower B cell counts and MHC-II expression on the cell surface of the B cells in B10.A mice compared to B10 mice. In order to investigate any differences in B cells, we harvested cells from the spleens of both B10 and B10.A mice, and used immunostaining and flow cytometry to identify the presence of T cells and B cells within these samples. We identified CD4 and CD8 T cells by their expression of TCR and CD4 or CD8, respectively and measured their frequency amongst all spleen cells. We identified B cells by their expression of B220 and measured the frequency of both the mature (IgD+) and the immature (IgD-) populations. We correlated the CD4:CD8 T cell ratios to the B cell frequencies and counts in each mouse. Furthermore, we compared MHC-II expression between the two strains by reverse transcription and quantitative PCR analysis.