HLA-E polymorphisms in hematopoietic stem cell transplantation.

Human leukocyte antigen (HLA)-E is an inhibitory ligand of natural killer cells and γ/δ T-cells. Differential expression of HLA-E alleles on the cell surface has been reported to influence outcome of hematopoietic stem cell transplantation (HSCT). We performed HLA-E genotyping in 116 HSCT patients and their HLA-matched unrelated donors. The impact of HLA-E genotypes on patient's overall survival (OS), disease free survival (DFS), cumulative incidences for relapse, transplant-related mortality (TRM) and acute graft vs host disease (aGvHD) was assessed. Neither univariate nor multivariate analysis showed any influence of HLA-E polymorphisms on the investigated endpoints of HSCT in our cohort. We could not confirm any of the previous observations in our cohort and consider it unlikely that HLA-E polymorphisms affect outcome of HSCT.

One amino acid change located in the conserved region of the alpha 1 domain specifies the novel HLA-C*07:147 allele.

The novel HLA-C allele HLA-C*07:147 contains one nucleotide substitution in exon 2 leading to an amino acid change in the alpha 1 domain from phenylalanine to leucine.

Sequence-based typing of major histocompatibility complex class I chain-related gene A alleles by use of exons 2-5 information.

The polymorphic MICA (major histocompatibility complex class I chain-related gene A) (Gene ID: 100507436) gene products are a ligand of the activating natural killer cell receptor, NKG2D. Their clinical importance spans from solid organ transplantation to bone marrow transplantation and disease susceptibility. Typing of MICA genes by sequencing is hampered by an exon 5 short tandem repeat, the definition of which is critical for the final allelic and functional assignment. We present a novel sequencing approach, which uses group-specific (7T/8T) exon 5 polymerase chain reactions (PCRs) and facilitates hemizygous exon 5 MICA-PCR in approximately 70% of the tested individuals. With this method we typed the International Histocompatibility Workshop Group MICA reference panel (40 cell lines) as well as 110 healthy South German blood donors. All ambiguities, with the exception of MICA*008:01/008:04 (synonymous substitution in exon 1) and MICA*009:01/049 (nonsynonymous substitution in exon 6), could be resolved with our method. Analysis of Hardy-Weinberg equilibrium for our cohort showed no significant difference between expected and observed frequencies of MICA alleles (P = 0.6142). The three most frequent alleles in our blood donor cohort were MICA*008:01/008:04 (40.5%), MICA*002:01 (13.2%), and MICA*009:01/049 (8.6%). The 7T polymorphism was observed in 67.7% and the 8T polymorphism in 32.3% of our blood donor cohort. Individuals (24.5%) tested were homozygous. The approach described in this paper is suitable for accurate sequencing of large sample numbers, including direct readout of exon 5 sequences. It is compatible with laboratory automation and commercial human leukocyte antigen analysis software tools. It may therefore be applied in large clinical trials.

Identification of candidate target antigens for antibody-based immunotherapy in childhood B-cell precursor ALL.

BACKGROUND: Contemporary risk adapted treatment protocols for childhood acute lymphoblastic leukemia (ALL) rely on accurate risk assessment strategies for disease re-occurrence by incorporating clinical parameters as well as immunological, molecular and cytogenetic features of the blasts at initial manifestation. Additional risk stratification is provided by analysis of the IN VITRO and IN VIVO response of the blasts towards standard chemotherapy. Despite adapted therapies, a number of children with good and bad prognostic factors still fail therapy. One approach to this problem might be to incorporate monoclonal antibodies (MoAbs) as additional modalities into the first or second line treatment. PATIENTS AND METHODS: In order to identify target antigen structures, we analyzed the immunological expression profiles of blasts from 181 patients with B-cell precursor ALL treated at our institution in 11 years according to the CoALL-92/97/03 protocols. Blasts were classified according to the EGIL guidelines as 9 proB-, 110 common (c-) and 62 preB-ALL. RESULTS: > 99 and 96 % of patients expressed CD19 and CD22 on > 90 % of their blasts, respectively. HLA-DR on > 95 % blasts was present in all patients. CD10 was expressed on all c-/preB-ALL and absent on proB-ALL cells. CD20 was expressed on 11-37 % of B-cell precursor ALL samples. CD34 positive blasts were found in 89, 83 and 68 % of patients with proB-, c- and preB-ALL, respectively. CD37 expression was detected in 0-18 % of patients. < 20 % CD45(+) blasts were found in 11, 19 and 18 % of patients with proB-, c- and preB-ALL. CD33(+) was expressed on 33, 29 and 21 % of patients samples with proB-, c- and preB-ALL. Other myeloid antigens (CD13, CD14, CD15, CD65) were positive on blasts in < 25 % of patients. Analyses of the immunological profile of blasts in 9 consecutive children with relapse revealed that the antigen expression profile varied little compared to the initial diagnosis for CD10, CD19, CD22 and HLA-DR. CONCLUSIONS: These analyses clearly identified the three antigens CD19, CD22 and HLA-DR present on blasts in more than 90 % of patients as potential target structures for targeted therapies with native or toxin-bound monoclonal antibodies in childhood ALL.