Purpose To describe a study to determine the influence of HLA class II matching on allograft rejection of high-risk, full-thickness corneal transplants.

Methods A prospective, longitudinal, clinical trial (ISRCTN25094892) with a primary outcome measure of time to first clinically determined rejection episode. Tissue typing used DNA-based techniques. Corneas were allocated to patients with ≤2 human leucocyte antigen (HLA) class I antigen mismatches by cohort minimisation to achieve 0, 1 or 2 HLA class II (HLA-DR) antigen mismatches. Transplants were to be followed up at 6 months and then annually on the anniversary of surgery for 5 years. Power calculations estimated a sample size of 856 transplants to detect a 0.1 difference in probability of rejection at 1 year between HLA class II matched and mismatched transplants at the 5% level of significance with 80% power.

Results To allow for loss to follow-up, 1133 transplants in 980 patients were accrued to the study between 3 September 1998 and 2 June 2011. 17% of transplants had 0 HLA-DR mismatches. The most frequent indication was bullous keratopathy, accounting for 27% of transplants and 54% of the transplants were regrafts. Median waiting time for a matched graft was 3 months. Donor and recipient characteristics were distributed evenly across the study groups.

Conclusion Recruitment to the CFS II has closed with 1077/1133 transplants meeting all the study criteria. Follow-up has been completed and final analysis of the data has started.

Trial registration number ISRCTN25094892 andUKCRNID9871, Pre-results.