Expression Profiling of Crtam in Cd8 T Cells during Acute Viral Infection
Open Access
- Author:
- Murdoch, Alexander Iain
- Area of Honors:
- Immunology and Infectious Disease
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Sorujit Sarkar, Thesis Supervisor
Dr. Pamela A. Hankey-Giblin, Thesis Honors Advisor - Keywords:
- CRTAM
CD8 T cells
T cells
immunology
effector - Abstract:
- During previous experiments of acute viral infection with Lymphocytic Choriomeningitis Virus, it was discovered through genome-wide microarray analysis that CRTAM mRNA was being significantly upregulated in CD8 T cells at the peak of the effector response as compared to naïve and memory CD8 T cells. This led us to ask the question - what are the CRTAM expression kinetics early after an acute viral infection and the relative tissue association for this upregulation. It was also thought that CRTAM could play a role in the differentiation of CD8 T cells into memory CD8 T cells. The experiments began with a screening of P14 chimeric transgenic mice at three time points (Naïve, day 8, and day 30) for upregulation in the expression of CRTAM. It was found that, indeed, CRTAM was differentially expressed in day 8 CD8 T cells in comparison to naïve and memory CD8 T cells. But only a very small subset of the population was expressing CRTAM at elevated levels. This led to the next experiment to test for CRTAM upregulation earlier in the time course of infection. Day 3 was selected as a time point that represents an early phase for CD8 T cell priming in this system. Again, CRTAM was upregulated on a small subset of the population but it was being expressed anywhere between half to a full logarithmic difference in comparison to the unactivated endogenous population of CD8 T cells. This was relatively early in the disease time course so the next experiment was to check expression over three days with strong controls on either end of the disease time course. Days 3, 4, and 5 were selected. Naïve and memory P14 chimeric mice were used as controls. Expression of CRTAM in CD8 T cells remained high in a small subset of the population, even more so at day 5 post-infection. However, day 5 samples showed higher percentage of the CD8 T cell population expressing CRTAM in higher quantities. It was clear that a small subset of the CD8 donor population was expressing CRTAM at higher levels than the rest of the population over the course of T cell proliferation, activation, and effector differentiation – day 3 through day 8. The focus was switched to see if the CRTAM +ve subset grew in size or intensity depending on the tissue location of CD8 T cells in the body. To determine this, CD8 T cells in the spleen, blood, liver, and lymph nodes of day 5 mice were stained for CRTAM. It was discovered that the lymph nodes showed much higher expression than the rest of the tissues. This matches previous research that ties CRTAM to retention of CD8 T cells in the lymph node for late phase activation through interactions with Necl-2. Overall, the experiments revealed an interesting subpopulation of CD8 T cells that express CRTAM in much higher quantities. But, the function of that subpopulation, whether it is to facilitate retention in the lymph nodes or whether there is no nominal function, is yet to be understood completely. The best procedure to follow these experiments is to isolate this subpopulation and stain it for more characteristics to understand why it expresses CRTAM in such high quantities and what the subpopulation contributes to the process of disease eradication in the body.