How exactly are kidneys matched to the best recipient?

Genetics. We all are born with different genes that express different proteins on our tissues. The best chance for a kidney transplant recipient is to get a kidney carrying proteins that are identical to the ones carried by the body ( identical twin donor) the next best thing is to get a kidney from a donor who has a lot of similarity with the recipient genetically to prevent rejection.
Here are some ... Kidney matching is designed to minimize transplanted kidney rejection by the recipient and done through special lab with special updated protocol by specially trained lab techs under professional supervision. For detail, ask the related staffs of the transplant centers timely and they will surely be happy to help you. .