HLA is short for Human leukocyte antigen. Matching needs to be done when doctors need to find umbilical cord blood or bone marrow for patients in desperate need.
It is not simple process and it is not as commonly believed enough to go out there and find a willing person.
Matching is very delicate and has to insure against bad effects from the transplantation. If donors and recipients HLA do not match body of the recipient will react violently. To avoid attack of ones cells on your donor cells or vice versa it is possible that donor cells will attack recipients body after the transplant, close HLA match is indisputable. HLA antigens are found in most cells in your body.
In few words it is a system human body developed to recognize which cells belong to it and which do not.
Match can be pronounced only when there is immunological compatibility.
Doctors perform blood tests to establish 3 general groups of HLA. After they fit you in one of 3 groups a search can start for somebody within same group that matches your HLA.
First and obvious choice for matching would be a family.
Some 70% of people who need a transplant will not find a match within their family. HLA is inherited and there is some 25% of chance that your brother or sister can be donors. Parents and children are not so common matches but it is not always worth checking within the group closest to you.
HLA matching needs to be done. It is for sure that test improves your chances for a successful transplant. You want to avoid possibility of your or foreign cells attacking each others and ruining your chances.
Graft versus host disease (GVHD) is an often result with variable intensity and degree.
If match is not found in your family you will be registered with category of unrelated donor or cord blood unit. There are millions of donors and 10's of thousands cord blood units where your doctor has a chance to find a match.