Kidney transplantation is a life-saving treatment of choice for patients with end-stage renal disease (ESRD). There are several factors such as the degree of HLA compatibility between donor and the recipient, pretransplant blood transfusions, the recipient's state of immunoreactivity and sensitization, immunosuppressive therapy is given in post-operative period, etc. is determining together the success of transplant result. Donor selection is accepted as the most critical factor for the long-term success of the transplantation. Crossmatch between the serum of the recipient and lymphocytes of the donor is the most crucial step of donor selection for kidney transplantation.
Crossmatch testing or crossmatching are the terms often used in connection with a kidney transplant. Still, many people wonder what it is and what is the importance of the crossmatch test for the kidney transplant.
This article will attempt to shed some light on the details of the crossmatch test for renal transplant by highlighting its importance.
What Is Crossmatch Testing?
By blood tests and crossmatch testing for the kidney transplant, we understand the comparison of blood and tissue samples acquired from both donor and recipient of a kidney transplant in order to ensure the graft survival and avoid especially the instant graft rejections and graft rejections happening within the first year after the renal transplantation. This test does not have a "normal" result. The goal of crossmatching is to find a compatible blood type for transfusion.
Crossmatch test for renal transplant has come a long way from rather primitive technique of HLA tissue typing to a multi-level crossmatch testing available nowadays in clinics conducting the kidney transplant surgeries. However, HLA tissue typing is still the first step of the whole crossmatching process. The HLA system includes a complex sequence of genes located on chromosome number 6 and their molecular products which play crucial roles in immune regulation and cellular differentiation. Human leukocyte antigen (HLA) molecules are expressed on almost all nucleated cells, and they are the major molecules that begin transplant rejection.
There are three basic types of HLA with different variants. If HLA types of donor and recipient in kidney transplant are the same or partially the same, the kidney transplant operation is more likely to end with success. However, the serum crossmatch brings a definite result, since it shows whether the recipient has antibodies which will attack the kidney transplant.
Crossmatching takes about 45 minutes to an hour. This process is actually a trial transfusion done in test tubes, in order to see exactly how your blood will react with potential donor blood.
The Importance of Crossmatch Testing for Kidney Transplant
Despite the astonishing developments in the field of medicine, a kidney transplant is still likely to fail if crossmatching shows that the donor and recipient are incompatible. HLA tissue typing insinuate the possibility of a successful kidney transplant. The incompatibility in HLA may be overcome if there is no antibody reaction in the serum crossmatch. However, serum crossmatch indicating a serious conflict leads to renal transplant not being conducted since even strongest medicines suppressing the defensive reaction may not be of any help. The crossmatch tests vary depending on the results of the antibody screening test and patient history. A full serologic crossmatch is required in patients with a history of significant antibodies found with the previous testing or in the current blood sample. The crossmatch process may be performed with either computer or serology.
Therefore, even in the era of new generations of immunosuppressing medicines, doctors will always conduct a cross-match test for the kidney transplant. They do not want to risk a situation where soon after the renal transplant they will be met with acute graft rejection which leads to health- and life-threatening medical conditions.
Blood Tests and Crossmatch Test for Kidney Transplant
Both donor and recipient are currently checked on three levels in order to ensure that renal transplant will succeed. These levels are:
- Blood Test – a simple cross match blood test for kidney transplant estimates the compatibility on the level of blood groups. As we know, there are four main blood groups of 0, A, B, AB with various compatibilities in accordance with Rh factor. If your crossmatch finds no antibodies, the possibility that your blood type will be incompatible with the donor type will be lower. If your crossmatch is positive, it means it's possible that antibodies were found. Then the antibodies must be isolated in a lab to find out the importance level of them.
If the blood test results are promising, doctors may pass to the second level of preparations for kidney transplant.
- Tissue Typing –tissue typing is used to establish the similarity between HLA in donor and recipient blood. If there is a significant degree of similarity, the risk of aggressive reaction in the serum crossmatching decreases. Each person's tissues, except for identical twins, are normally different from anyone else's. It is believed that the better the HLA match, the more successful the transplant over a long period of time.
- Serum Crossmatching –serum crossmatching is what we understand as an actual crossmatch test for kidney transplant. A serum crossmatch is a blood test that cells from the donor are mixed with your serum. If your serum has antibodies against the donor's cells, the antibodies will attack them. If the antibodies are at high levels, the donor cells will be destroyed. This is called a positive crossmatch, and it means that the transplant cannot happen.
Crossmatching between the Family Members – Is It Necessary?
Unfortunately, being a family does not mean that your crossmatch test for renal transplant will be automatically negative (which means no reaction and the possibility of kidney transplant). Two children may inherit the very same HLA from their parents, and become "identical match", while another child in the same family can inherit a different combination of HLA.
For this reason, even between twins, doctors will conduct a serum crossmatch.
This content is edited by Flymedi Medical Editors in April 2019.