One of the major discoveries found during the initial bone marrow transplants was the human leukocyte antigen (HLA). The HLA is a type of antigen protein found on the cell surface. HLA mainly contains of six major antigens that are highly variable in the human population, therefore they are almost unique to each individual.
They are markers present on the outer surface of body cells, recognized by the immune system, to distinguish between self cell, pathogen-infected cell and foreign cell. A child inherits HLA antigens from both parents to form his/her own unique HLA typing. For a bone marrow transplant to be operable it requires a perfect match of HLA types between the donor and the recipient.
However, a partial match of only 4 pairs of antigen is sufficient for cord blood transplant.
Stem cell compatibility in HSC transplants
| Example of search for compatible cord blood unit | |||||||
| HLA type | A1 | A2 | B1 | B2 | DRB11 | DRB12 | Matching result |
| Patient | *02CRFN | *11BDFZ | *15DJVP | *51DREH | *0803 | *0406 | / |
| Sample 1 | *02ANJ | *3303 | *3802 | *4601 | *0901 | *1502 | Incompatible |
| Sample 2 | *02CRFN | *11BDFZ | *15DJVP | *51DREH | *0803 | *0406 | Perfect match |
| Sample 3 | *02ANDC | *11BDFZ | *1511 | *3905 | *0901 | *14SXE | 1/6 HLA match only |
| Sample 4 | 802ANJ | *11BDFZ | *40DGWB | *51DREH | *0803 | *0406 | 4/6 HLA match |
Bone marrow transplant：only sample 2 is suitable for transplant
Cord blood transplant：sample 2 and 4 are suitable for transplant.
