Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 12, 2013
Publication Date: August 12, 2013
Citation: Maggioli, M., Palmer, M.V., Vordermeier, H.M., Estes, D.M., Waters, W.R. 2013. Effector and memory T cell subsets in the response to bovine tuberculosis [abstract]. Iowa State University College of Veterinary Medicine Annual Research Day. Abstract No. 20. Technical Abstract: Long-term (i.e., 14 days) cultured IFN-gamma ELISPOT assays of peripheral blood mononuclear cells (PBMC) are used to access T cell central memory (Tcm) responses in both cattle and humans. With bovine tuberculosis, vaccine-elicited long-term IFN-gamma ELISPOT response correlates with protection; however, the phenotype of the IFN-gamma producing cells has not been defined. The present study describes the contribution of Tcm, T effector memory (Tem), and T effector cells to IFN-gamma production in ex vivo and long-term assays (n = 8) in response to aerosol M. bovis infection. PBMCs were stimulated with M. bovis purified protein derivative (PPDb), rESAT-6:CFP-10 (E:C) and over-lapping peptide cocktails of Tb10.4 and Ag85A for 13 days, with periodic addition of fresh media and rIL-2. On day 13, cultured PBMC were re-stimulated with medium alone, E:C, or PPDb with fresh autologous adherent cells for antigen presentation. After 20h the expression of IFN-gamma, CD4, CD45RO, CD62L, CD44, and CCR7 (rat anti-human CD197) were analyzed by flow cytometry. In response to E:C or PPDb, ~75% of CD4+, IFN-gamma+ cells expressed Tcm phenotype (CCR7+, CD62Lhi, CD45RO+) and ~24% expressed Tem phenotype (CCR7-, CD62Lmod, CD45RO+). The PBMC ex vivo response to E:C or PPDb consisted of ~56-59% T effector cells (CCR7-, CD62Llo, CD45RO-) and ~37-42% Tem cells. Only 3-4 % of the ex vivo response consisted of Tcm cells. In response to E:C, expression (MFI) of CD62L differed significantly among Tcm (189 ± 47), Tem (68 ± 14) and T effector (13 ± 2) cells. CD44 expression on Tcm (71 ± 8) in E:C stimulated cultures exceeded that of Tem (25 ± 3) and T effector (27 ± 3) cells. Similar responses to PPDb were observed. These findings confirm that the long-term cultured ELISPOT assay to M. bovis antigens primarily measures Tcm responses by cattle to M. bovis infection.