Different mechanisms causing loss of mismatched human leukocyte antigens in relapsing t(6;11)(q27;q23) acute myeloid leukemia after haploidentical transplantation
Mismatched human leukocyte antigens (HLAs) on leukemic cells can be targeted by donor T cells in HLA‐mismatched/haploidentical stem cell transplantation. In two cases of acute myeloid leukemia with t(6;11)(q27;q23) abnormality presented here, flow cytometry analysis showed a lack of HLA‐A unshared between recipients and donors in relapsing leukemic cells after HLA‐haploidentical transplantation. However, high‐resolution HLA genotyping showed that one case lacked a corresponding HLA haplotype, whereas the other preserved it. These cases suggest that leukemic cells, which lacked mismatched HLA expression, might have an advantage in selective expansion under donor T‐cell immune surveillance after HLA‐haploidentical transplantation. Most importantly, down‐regulation of unshared HLA expression potentially occurs by genetic alterations other than loss of HLA alleles.
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Document Type: Research Article
Publication date: December 1, 2012