Info
Types of Allo HSCT
based on donor/recipient matching of major HLA antigens on Chr. 6 (4 principal genes for serotyping: HLA-A, -B, -C, & -DR; each w/ 2 alleles ∴ 8 major Ag)
- Matched related (MRD, sibling 8/8 major Ag match):
- lowest GVHD; preferred donor
- Matched unrelated (MUD):
- ↑ risk of GVHD; ∴ matching of 10 HLA alleles (DQ also) to ↓ risk; chance of match correlates w/ ethnicity (NEJM 2014;371:339)
- Mismatched related (eg, 1/8 Ag mismatch):
- ↑ available donor pool, but ↑ GVHD, rejection; ∴ need additional immunosuppression
- Haploidentical:
- typically, between parents and young children or sibs (“half” match); early post-tx cyclophosphamide reduces GVH by destroying proliferating alloreactive T-cells
- Umbilical cord blood:
- HSC processed at birth & stored. Yields lower cell number. Need 2 cords per adult. Neonatal immune cells: HLA-mismatch tolerated better, ↓ GVHD, slow immune reconstitution → ↑ late viral infections (Blood 2010;116:4693).
Graft-vs.-host disease (GVHD)
undesirable side effect of allo HSCT allogeneic T cells view host cells as foreign; ↑ incid. w/ mismatch or unrelated donors
Graft-vs.-tumor (GVT)
desired effect in allo-SCT; graft T cells attack host tumor cells