"HLA Typing
HLA typing is done on potential donors and recipients. In transplantation we try to match as many antigens as possible. Antigen matches of 5 and 6 antigens and some 4-antigen matches have better clinical outcomes (i.e., the patient is less likely to reject the transplanted organ), especially in kidney and bone marrow transplants.
	The degree of HLA matching needed or suitable for successful solid organ transplantation depends on the type of organ and degree of acceptable risk. Certain organ and tissue transplants need a closer histocompatibility match than other organs. For example, a cornea transplant can be accepted by nearly anyone because corneas are avascular and therefore no antibodies reach the cornea to cause rejection. In kidney and bone marrow transplantation, HLA matching is very important, since these transplants are at high risk for graft rejection. On the other hand, for liver transplants, HLA mismatches have little impact on graft survival. Heart and lung transplants fall somewhere in between but minimizing HLA mismatches significantly improves survival. For liver, lung, and heart transplants, few donors are available and it is hard to get good HLA matches.
	Transporting and storing donated organs can take time. The “best” match may live many miles from the “ideal” recipient. The need to have the “best” matches must be balanced against the time it takes to procure and transport a donated organ and then transplant it.
Panel of Reactive Antibodies
A panel of reactive antibodies (PRA) shows the recipient’s sensitivity to various HLAs before receiving a transplant. To detect preformed antibodies to HLA, the recipient’s serum is mixed with a randomly selected panel of donor lymphocytes to determine reactivity. The potential recipient may have been exposed to HLA antigens by previous blood transfusions, pregnancy, or a previous organ transplant.
	PRA allows for the determination of whether a recipient is of high or low reactivity to potential donors. The results for the PRA are calculated in percentages. A high PRA indicates that the person has a large number of cytotoxic antibodies and is highly sensitized, which means there is a poor chance of finding a crossmatch-negative donor. In patients awaiting transplantation, a PRA panel is usually done on a regular basis. In highly sensitized patients (high PRA), plasmapheresis and IV immunoglobulin (IVIG) can be used to lower the number of antibodies."
Reference: Hardin, M., Kwong, J., Roberts, D., Hagler, D., & Reinisch, C. (2020). Lewis’s medical-surgical nursing: Assessment and management of clinical problems, (11th ed.). St. Louis, MO: Elsevier.

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