To investigate the role of CD4 and CD8 T cells in arthritis, we generated transgenic mice deficient in CD4 and CD8 molecules expressing RA-susceptible gene HLA-DQ8. DQ8-CD4-/- mice were resistant to developing collagen-induced arthritis (CIA). However, DQ8-CD8-/- mice developed CIA with increased incidence and more severity than DQ8 mice. Both DQ8·CD8-/- and DQ8 mice produced rheumatoid factor. In addition, DQ8·CD8-/- mice produced antinuclear Abs. The B cell compartment and expression of DQ8 were normal in all the strains, although frequency of cells expressing DQ8 was less in CD4-/- mice. An increased frequency of CD3+ double-negative (DN) T cells was found in DQ8-CD8-/- compared with DQ8·CD4-/- and DQ8 mice. These CD3+ DN T cells produced high amounts of IL-10 in CD8-deficient mice. Analysis of cell division using a cell cycle tracking dye showed a higher rate of division of CD3+ and CD3+ DN T cells in DQ8·CD8-/- mice compared with DQ8·CD4-/- and DQ8 mice. Decreased apoptosis was seen in CIA-susceptible DQ8 and CD8-deficient mice, indicating a defect in activation-induced cell death. These observations suggest that CD4 cells are necessary for initiation of CIA in DQ8 mice. We hypothesize that CD8+ T cells are not capable of initiating CIA in DQ8-transgenic mice but may have a regulatory/protective effect.
ASJC Scopus subject areas
- Immunology and Allergy