One of the main barriers to allogeneic transplantation is the recognition by the host's immune system of foreign non‐self histocompatibility antigen on the donor tissue. The major target for these alloresponses are the highly polymorphic HLA molecules, encoded within the major histocompatibility complex.
In clinical practice the histocompatibility laboratory facilitates the selection of the most suitable allogeneic donor. In solid organ transplantation HLA matching provides an important parameter in donor selection. Prior sensitisation of the recipient with the development of donor‐specific HLA antibodies is associated with increased risk of rejection and poorer graft outcome. New more sensitive solid‐phase assays allow the detection of such antibodies not previously recognised by traditional crossmatch techniques, allowing for better donor selection and post transplantation monitoring.
In HSC transplantation HLA matching is critical. Whilst the ideal donor remains the completely HLA matched family donor, the use of new techniques for high resolution HLA typing is now allowing the selection of suitable well matched unrelated donors from volunteer panels with similar outcome, resulting in the more widespread application of this life saving therapy.
Any successful allogeneic transplant program requires an effective interaction between its histocompatibility laboratory, clinicians, scientists, donor coordinators, donor registries and transplant centres.