Effect of major histocompatibility complex haplotype matching by C4 and MICA genotyping on acute graft versus host disease in unrelated hematopoietic stem cell transplantation

Abstract

Background: Human leukocyte antigen (HLA) matching between the donor and recipient is an important factor for the prognosis of hematopoietic stem cell transplantation (HSCT) in patients with hematologic malignancies. However, many other genetic factors are related to the outcomes of HSCT. In this study, we explored whether matching of HLA haplotypes between the recipient and donor can be predicted by C4 and MICA typing as proxy markers, and whether it is associated with the incidence of acute graft versus host disease (aGVHD).

Methods: DNA preparations collected from a total of 59 recipient and unrelated donor pairs were used for PCR-based C4 subtyping and MICA sequence-based typing. Additional samples from 22 recipient and related donor pairs were also assayed for C4 subtyping. Medical records and clinicopathologic status including development of aGVHD were compared according to the groups classified by the results of C4 and MICA typing. A single nucleotide polymorphism (SNP) microarray analysis for six selected recipient/donor pairs was performed to determine matching of various genes located in and around the HLA region between the recipients and donors.

Results: The six most common MICA alleles with frequencies greater than 10% in this study were MICA*008:01, *010:01, *002:01, *004, *009:01/049, and *012:01, and they were significantly associated with HLA-B*07:02, *15:01, *58:01, *44:03, *52:01, and *54:01, respectively. Among the 59 unrelated pairs, HLA alleles were matched in 34 (57.6%) and mismatched in 25 (42.4%). C4 subtypes were identical between the recipient and donor in 28 (82.4%) HLA-matched unrelated pairs, while MICA genotypes were matched in all HLA-matched unrelated pairs. In the related pairs, all 22 recipients showed the same C4 subtypes with their respective HLA-matched donors. C4-mismatched cases showed a higher incidence of aGVHD than the C4-matched group regardless of an HLA match in the unrelated group (P=0.009). In multivariate analysis, C4 mismatch was also a significant risk factor associated with the development of aGVHD in unrelated HSCT cases (hazard ratio=3.24, P=0.006). Among more than 3,000 SNPs belonging to the MHC domain, 96.6% and 95.8% were identical in the two HLA/MICA/C4-matched recipient and donor pairs, while 96.4% and 86.3% were identical in the two HLA/MICA-matched but C4-mismatched pairs.

Conclusions: PCR-based C4 subtyping is a simple method for assessing the genetic identity of the HLA region between a recipient and unrelated donor. C4 mismatch was also related with an increased incidence of aGVHD. Thus, this test would be useful for donor assessment and prediction of aGVHD in HSCT.