Question 

I am currently on the Transplant waiting list. During a call for a possible kidney, which due to unforeseen circumstances did not go ahead, I was told the match was 210. I have read some information about tissue typing but find it has too much jargon. Is it possible to have a clear, uncomplicated, explanation of what the numbers mean and what is classed as a good match and why?  

Answer 

We will often refer to the transplant match when discussing kidney transplant offers from the organ donor register or when deciding if a live donor transplant would be suitable. The match refers to how similar the organ donors tissue type is to your own. 

We all have our own unique tissue type expressed on most of our body’s cells, a bit like your own unique barcode. This helps our body to identify and fight infections for example, and so keeps us alive and well. This tissue type becomes a problem when we need a transplant. The tissue type on the cells of a donor kidney can be picked up as not belonging to us and would trigger our body to try and reject or kill off the donor kidney. We try and reduce this risk by finding a donor kidney with as similar a tissue type to ourselves as possible. 

This tissue type is called Human Leucocyte Antigen or HLA for short. There are several HLA proteins, but we focus our matching on 3 HLA proteins named A, B and DR. We inherit our HLA from our parents, one from each parent, so we have 2 HLA A’s, 2 HLA B’s and 2 HLA DR’s. Each HLA is given a number and the purpose of matching is to try and find a donor with as many of the same numbers as yours. A bit like your lottery numbers!  

Just to make it a bit more confusing we talk about the number of mismatches you have rather than the number of matches! So, your transplant match of 210 tells you that you would have 2 mismatches at HLA A, 1 at HLA B and 0 mismatches at DR or 3 mismatches in total. The most ideal match would be 000, where the HLA of the donor is the same as yours. However, a transplant with a mismatch of 222, so no HLA the same, can still go ahead but your doctor would look at other factors such as the age of the donor, whether a live donor or a deceased donor and how likely it would be to find another match in the future. The transplant mismatch helps your transplant doctor decide your risk of rejection after having a transplant and guide choices regarding immunosuppression medication. 

Rachel Middleton 

Consultant in Renal Medicine Northern Care Alliance 

Honorary Lecturer University of Manchester