Submitted to: International Colloquium on Paratuberculosis
Publication Type: Abstract Only
Publication Acceptance Date: 5/11/2005
Publication Date: 8/14/2005
Citation: Stabel, J.R., Khalifeh, M.S., Soenksen, K. 2005. Expression of CD5 on Lymphocytes in Cattle with Paratuberculosis [abstract]. International Colloquium on Paratuberculosis. p. 161.
Technical Abstract: CD5 is a cell surface molecule involved in antigen recognition and is present on all T lymphocytes and a subset of B lymphocytes. Recent work in our laboratory involving cattle infected with Mycobacterium avium subsp. paratuberculosis (Johne’s disease) has demonstrated a differential expression of the CD5 marker on peripheral blood B cells, with a shift in B cell expression from CD5dim to CD5bright as disease progresses from a subclinical to a clinical state. Previous research has also shown an increase in the number of B lymphocytes and an increase in CD4+ T lymphocytes in peripheral blood as disease progression occurs. The purpose of this study was to examine lymphocyte subsets and CD5+ expression on peripheral blood B and T cells from healthy, noninfected cattle and cattle in subclinical and clinical stages of paratuberculosis. Peripheral blood mononuclear cells (PBMC) were isolated, cultured in presence or absence of live M. paratuberculosis, and then analyzed by flow cytometry for CD5 expression within the lymphocyte subpopulations. Analysis demonstrated an increase in B lymphocytes in clinical animals as compared to subclinically infected cows which is in agreement with previous findings. In addition, three distinct subpopulations within the CD5 cell population were identified: CD5dim, CD5bright, and CD5extra bright. A significant decrease in the CD5dim B cell population along with a concomitant increase in the CD5bright B cell population was observed in subclinically and clinically infected cows. No significant differences were observed in CD5+ expression due to cow infection status within T cell subpopulations. However, the CD5bright subpopulation was significantly higher within gamma/delta and CD8 T cell populations, compared to a higher expression of the CD5extra bright subpopulation within CD4 T cells. In vitro infection with live M. paratuberculosis did not result in significant changes in B or T cell populations or affect CD5+ expression patterns on B or T lymphocytes. These results suggest that changes in CD5+ expression on B lymphocytes in animals with paratuberculosis may reflect a shift in host immunity during the disease process.