Table 1. Level of Human Leukocyte Antigen (HLA) Typing Currently Used for Different Hematopoietic Stem Cell Sourcesa,b
| | Class I Antigens | Class II Antigens |
| Stem Cell Source | HLA A | HLA B | HLA C | HLA DRB1 | HLA DQB1 | HLA DPB1 |
| Matched Sibling BM/PBSCs | Antigen | Antigen | Optional | Allele | | |
| Matched Sibling/Other Related Donorc BM/PBSCs | Allele | Allele | Allele | Allele | Optional | Optional |
| Unrelated Donor BM/PBSCs | Allele | Allele | Allele | Allele | Optional | Optional |
| Unrelated Cord Blood | Antigen (Allele Optional) | Antigen (Allele Optional) | Allele Optional | Allele | Optional | Optional |
| BM = bone marrow; PBSC = peripheral blood stem cells. |
| aHLA antigen: A serologically defined, low-resolution method of defining an HLA protein. Differs from allele-level typing half of the time. Designated by the first two numbers (i.e., HLA B 35:01—antigen is HLA B 35). |
| bHLA allele: A higher resolution method of defining unique HLA proteins by typing their gene through sequencing or other DNA-based methods that detect unique differences. Designated by at least four numbers (i.e., HLA B 35:01). |
| cParent, cousin, etc., with a phenotypic match or near-complete HLA match. |
