Q: My friend is willing to donate his kidney to his sister. The HLA test shows only two matches and LCM test result is positive 80%. In this condition, is he a better donor or any other related or unrelated donor hla + lcm should be tried?

A:Immunological compatibility between the potential donor of the kidney and the recipient depends firstly, upon the degree of matching of HLA antigens; and secondly, whether the recipient has any previously formed sensitivity (in the form of preformed antibodies) to that donor. When all the six concerned HLA antigens match or when the number of mismatches between the antigens is zero, it would be considered a perfect match. This compatibility significantly improves the long-term survival of the transplanted kidney in the recipient. Lymphocyte cross-matching is a test to detect the presence of preformed antibodies in the recipient against the HLA antigens of the potential donor. Presence of anti-HLA antibodies in the recipient would result in higher incidence of rejection and poor survival of the transplanted kidney. With only 2 HLA matches and 80% positive crossmatch, the brother would not be a suitable candidate for the kidney donation. However, other potential donors from the recipient’s blood relation should also be tested for HLA typing to ascertain the degree of matching and to make sure no possible donors are overlooked. Finally, one can also seek an unrelated donor for the transplant if it happens to be well matched and the recipient doesn’t have a preformed sensitivity to the potential donor (called “negative cross-match”).