| First Author | Bitsaktsis C | Year | 2006 |
| Journal | J Immunol | Volume | 177 |
| Issue | 7 | Pages | 4644-51 |
| PubMed ID | 16982903 | Mgi Jnum | J:139316 |
| Mgi Id | MGI:3807741 | Doi | 10.4049/jimmunol.177.7.4644 |
| Citation | Bitsaktsis C, et al. (2006) Fatal recall responses mediated by CD8 T cells during intracellular bacterial challenge infection. J Immunol 177(7):4644-51 |
| abstractText | The roles(s) of CD8 T cells during infections by intracellular bacteria that reside in host cell endocytic compartments are not well understood. Our previous studies in a mouse model of human monocytotropic ehrlichiosis indicated that CD8 T cells are not essential for immunity. However, we have observed an unexpected role for these cells during challenge infection. Although immunocompetent mice cleared a primary low-dose (nonfatal) Ixodes ovatus ehrlichia infection, a secondary low-dose challenge infection resulted in fatal disease and loss of control of infection. The outcome was CD8-dependent, because CD8-deficient mice survived secondary low-dose challenge infection. Moreover, effector and/or memory phenotype CD8 T cells were responsible, because adoptive transfer of purified CD44(high) CD8 T cells to naive mice induced fatal responses following a primary low-dose infection. The fatal responses were perforin- and Fas ligand-independent, and were associated with high serum concentrations of TNF-alpha and CCL2, and low levels of IL-10. Accordingly, blockade of either TNF-alpha or CCL2 ameliorated fatal recall responses, and in vitro coculture of memory CD8 T cells and Ixodes ovatus ehrlichia-infected peritoneal exudate cells resulted in substantial increases in TNF-alpha and CCL2. Thus, during monocytotropic ehrlichiosis, inflammatory cytokine production, by CD8 T cells and/or other host cells, can trigger chemokine-dependent disease. These findings highlight a novel role for CD8 T cells, and reveal that live vaccines for intracellular bacteria can, under some conditions, induce undesirable consequences. |
