Long-Term Stability of Minimally Invasive Radial Keratotomy for Mild to Moderate Keratoconus.

Purpose: This study aimed to evaluate the long-term stability of minimally invasive radial keratotomy (mini-RK) for eyes with mild to moderate keratoconus.

Design: Retrospective observational case series.

Methods: Eleven eyes from 6 patients with hard contact lens (HCL)-intolerant keratoconus underwent mini-RK and were followed up for more than 5 years.

MHC class I and II antigens as targets of rejection in penetrating keratoplasty in low- and high-risk mouse eyes.

Purpose: To determine the extent to which expression of major histocompatibility complex (MHC) class I and II molecules contributes to rejection of orthotopic corneal transplants in mice.

Methods: Full-thickness corneas, prepared from eyes of normal C57BL/6 (B6) and BALB/c mice and from B6 mice in which the class II gene I-A or the beta2-microglobulin (beta2mu) gene was disrupted, were placed orthotopically in low- or high-risk eyes of BALB/c (fully incompatible), BALB.B [minor histoincompatible (H) only], and bm12 (class II only disparate) recipients.

CD95 ligand expression on corneal epithelium and endothelium influences the fates of orthotopic and heterotopic corneal allografts in mice.

Purpose: To determine the extent to which CD95 ligand (CD95L) expressed on corneal epithelium and endothelium influences survival of cornea grafts placed orthotopically and heterotopically in the anterior chamber (AC), an immune-privileged site.

Methods: Corneas from eyes of C57BL/6 (B6) and B6.gld (CD95L deficient) mice were (1) rendered into small full-thickness fragments, with or without an epithelial layer, and placed behind recipient corneas in the ACs of BALB/c eyes, while BALB/c corneas were similarly implanted in eyes of B6 and B6.

A CIITA-independent pathway that promotes expression of endogenous rather than exogenous peptides in immune-privileged sites.

A CIITA-independent pathway of MHC class II expression has been found in the eye and the brain, both immune-privileged sites. Although corneal endothelial cells were unable to express MHC class II in response to IFN-gamma alone, these cells readily expressed MHC class II molecules via a CIITA-independent pathway when triggered by simultaneous exposure to IFN-gamma and TNF-alpha. CIITA-independent expression of MHCclass II molecules enabled corneal endothelial cells to present cytosolic, but not endosomal, ovalbumin (OVA) to OVA-primed T cells.

The role of minor histocompatibility alloantigens in penetrating keratoplasty.

Background/aims: To review the experimental evidence that implicates minor histocompatibility (H) antigens in the vulnerability of orthotopic corneal transplants to rejection, and to speculate on the possible role of minor H antigens in penetrating keratoplasty in humans.

Methods: Orthotopic corneal transplantations have been conducted in numerous inbred strains of mice and rats, and the fate of these grafts, as well as the immune responses mounted by recipients, have been examined in vivo and in vitro.

Results: Minor H antigens have been found to be more important barriers to the success of orthotopic corneal transplants in rodents than have grafts disparate at the major histocompatibility complex (MHC).

Allogeneic neonatal neuronal retina grafts display partial immune privilege in the subcapsular space of the kidney.

Transplantation of immature retinal tissues may offer a solution for restoring sight to individuals afflicted with degenerative retinal diseases. Promising results have recently demonstrated that neonatal retinal grafts placed in the eye can survive, differentiate into photoreceptor cells, and respond to evoked electrical stimuli. These transplants, however, were performed in immunologically immature recipients.