Abstract
Purpose: :
Foxp3+ T regulatory cells have been reported to have an impact on immune regulation and promoting acceptance of various organ grafts. We have previously reported that local expansion of Foxp3+CD4+T regulatory cells within the cornea is one of the mechanisms of immune privilege of corneal allografts. To further investigate the role of Foxp3+T regulatory cells on acceptance of corneal allografts, we elucidate the correlation between the proportion of Foxp3+ T regulatory cells in the secondary lymphoid organs and corneal allograft survival.
Methods: :
Normal corneas of C57BL/6 and BALB/c were transplanted orthotopically into the normal eyes of BALB/c mice, and graft survival was assessed. Spleen and cervical lymph nodes (LN) were removed from the recipients bearing (1) syngeneic grafts, (2) accepted allografts, and (3) rejected allografts at 3 weeks after grafting. Expression of Foxp3 on CD4 and CD8 in spleen cells and LN cells of these recipients was assessed by flow cytometry, and compared.
Results: :
The proportion of Foxp3+ cells in LN cells from the recipients bearing (1) syngeneic grafts, (2) accepted allografts, and (3) rejected allografts was statistically indistinguishable. On the other hand, the proportion of Foxp3+ cells in spleen cells from the recipients bearing rejected allografts was significantly lower than those in the recipients bearing syngeneic grafts or accepted allografts (p=0.006, p=0.005, respectively). The proportion of splenic Foxp3+CD8+ cells, but not Foxp3+CD4+ cells, in the recipients bearing rejected allografts was significantly lower than those in the recipients bearing syngeneic grafts or accepted allografts (p=0.035, p=0.004, respectively).
Conclusions: :
The proportion of splenic Foxp3+CD8+T regulatory cells correlates with corneal allograft survival at early periods after grafting. It is indicated that Foxp3+CD8+T regulatory cells in the spleen plays an essential role in the acceptance of corneal allografts.
Keywords: immune tolerance/privilege • immunomodulation/immunoregulation • transplantation