Question

Explain why it is necessary to match at least some of the HLA allotypes between donor and recipient in a bone marrow transplant given to remedy SCID?

Answer 1

Ans: HLA stands for Human Leukocyte Antigens are the proteins marker present on the cell. This HLA are used by the immune system present in our body for the identification of cell. Identification in the sense of which cell are the part of the body or which cell are foreign invaders. After recognizing this immune system attack those foreign invaders cell. For this reason, it is very important to match the HLA between the donor and patients.

For a donor to donate to the patient for bone transplant HLA matching in SCID is important. However some times it is not possible for finding a match due to the reason of the uniqueness of some HLA types. Moreover, these HLA are also inherited. This inherited makes possible for siblings to match HLA. Also, the same ancestry or the ethnic background can also have a chance of HLA matching. SCID is a rare disorder which is caused by the mutation. This mutations are on the genes which are helpful in the functioning of the immune cells.

It is always necessary for some matching of HLA in the transplant of the bone marrow because:

• The same HLA makes a maximum chance for successful operation for transplant.
• Transplant with the same HLA will help the patient body to grow new blood cells with the mechanism of cell engraft.
• There is a possible chance of certain complications like GVHD (Graft-versus-host disease). This type of complications occurs when the graft (immune from the donated cell) started to attack the host cell by considering it as foreign invader element. Thi type of complications is reduced in transplantation with the same HLA.

However, a complete match of the HLA is not always possible. For this reason half of the matching in HLA is also considered. this type of transplant is called a haploidentical transplant.

Patient with SCID has a pre problem in the genes that regulates the functioning of the immune system. If same or at least half of the type of HLA in bone transplant is not available then the transplant will be not successful and there is a chance of many complications like GVHD. which can cause the patient to have attacked by the donated cell to the host cell. The situations becomes worst when there is a chance of multiple organ failure due this attack. Hence it is important to match some of the HLE haplotypes for the bone marrow transplant in a patient with SCID disorders.