A clinician's outlook on HLA matching for keratoplasty.

Background: A clinician's view of HLA matching for keratoplasty (kp) must basically be a rather pragmatic one: as immunosuppressives are getting more and more potent with acceptable toxicity, what advantage does HLA matching offer in addition to or supplementing immunosuppressives? Also, one wants to know what can be expected of further fundamental progress in this field in the future.

Methods: The author tries to answer these questions based on three sources: (1) the papers in this volume, all written by highly experienced and leading specialists in their field; (2) the international kp literature, and (3) the author's own kp experiences of 30 years' duration with many clinical studies derived therefrom.

Results: There is no doubt that HLA matching has a great potential in kp and works already well on a statistical basis in high-risk as well as in normal-risk patients. In the individual kp patient, however, a decision as to what extent current HLA matching would be useful and advisable is a question far less easy to answer. This is exemplified by clinical examples.

Conclusions: HLA matching, as it is practically feasible now, is recommended as an adjunctive immunoprophylactic measure for every patient for whom the calculable waiting time is tolerable. Matching should, whenever possible, comprise HLA-A/-B as well as -DR matching and should, if possible, be performed on solid molecular grounds. In the future, the new 'weighted' concept of permissible versus taboo mismatches will become more and more operative and will substitute the current still simple matching criteria which can nothing more than respect unweighted numbers of fitting alleles. It seems probable that sometime later still more refined systems (e.g. 'minors') will supplement or even partially substitute current HLA typing. In whichever direction typing and matching will continue to develop in the future, it seems clear by now that a systematic start into typing and matching in keratoplasty is inevitable for all those surgeons and cornea bankers who want to keep on with progress in this field.