Fate of orthotopic corneal allografts in C57BL/6 mice

Our aim was to determine whether corneal allografts placed in normal eyes of C57BL/6 mice enjoy immune privilege, and whether recipients of long-standing grafts acquire donor-specific ACAID. C57BL/6 mice received corneal grafts from BALB/c, C57BL/6, C3H, B10.D2 or BALB.B mice; for comparison, BALB/c mice received C3H or C57BL/6 corneal allografts. Delayed hypersensitivity and anterior chamber associated immune deviation (ACAID) induction were assessed in recipient mice at four and eight weeks after grafting. It was found that C57BL/6 mice resemble BALB/c mice in mounting more vigorous rejection reactions against minor H, rather than MHC, alloantigenic corneas, and in the acquisition of donor-specific DH within four weeks of engraftment. In addition, C57BL/6 mice with long-standing, healthy allografts display donor-specific ACAID. However, C57BL/6 mice differ from BALB/c mice in that (1) fewer allodisparate corneal grafts were accepted indefinitely; and (2) rejection in these eyes correlated with sustained donor-specific DH. It was concluded that immune privilege is less secure in the eyes of C57BL/6 mice, compared to BALB/c mice. This conclusion is discussed in terms of known polymorphic differences between these mouse strains at genetic loci governing (a) immune responsiveness, (b) alloform of Fas ligand, and (c) bias of immune response toward Th1 or Th2 phenotypes.