HLA-B gene somatic insertion/deletion mutations in patients with acute myelogenous leukaemia.

Loss of heterozygosity is considered to be the most common type of tumour-specific somatic mutation of the human leucocyte antigens (HLA) genes in patients with haematological malignancies. Nevertheless, subtle DNA sequence changes, namely short insertions/deletions, may also abolish the expression of HLA molecules and interfere with routine HLA typing. Two male patients with acute myelogenous leukaemia (AML) were indicated for the search of a suitable donor for allogeneic haematopoietic stem cell transplantation (aHSCT). The patients and their relatives were initially HLA typed by serological and DNA techniques at a low-resolution level. The HLA high-resolution (HR) type was obtained by means of sequencing-based typing (SBT). In both cases, anomalous frameshifts in the sequence were observed in the HLA-B gene, namely in exon 3 (Case 1, heterozygous deletion of two bases) and exon 4 (Case 2, heterozygous insertion of two bases). In the second case, the insertion variant was associated with a loss of HLA-B8 expression. To reveal whether these sequence patterns may be caused by somatic mutations in the malignant cells, blood sample in remission (Case 1) and buccal swab sample (Case 2) were collected from the patients. In an important manner, the SBT in these germline samples revealed common HLA-B*07:02,*15:01 (Case 1) and HLA-B*08:01,*35:02 (Case 2) types with no evidence for the sequence alteration observed in the initial samples. In conclusion, the insertion/deletion sequence variants of the HLA-B gene in two patients were limited to the initial blood samples with a substantial proportion of AML cells and thus may be attributed to the somatic mutation in the malignant cells. HLA somatic mutations should be taken into account in patients with haematological malignancies to prevent HLA mistyping and inappropriate selection of an aHSCT donor.

Profile of Inflammation-Associated Proteins in Early Post-Transplant Samples of Patients After Allogeneic Hematopoietic Stem Cell Transplantation: a Preliminary Study.

Allogeneic hematopoietic stem cell transplantation (aHSCT) is used as a curative treatment in severe hematological and immunological disorders. Despite clear improvement of the aHSCT outcome, substantial proportion of patients still suffers from severe complications, including graft-versus-host disease (GvHD). The aim of this study was, therefore, to identify inflammation-associated molecules deregulated in the early serum samples of the patients after aHSCT and nominate markers associated with particular aHSCT parameters/complications. Serum concentrations of 92 inflammation-associated proteins were measured in samples obtained from 80 aHSCT patients 14 days after transplantation and from 23 healthy control subjects by a novel sensitive proximity extension assay technology using Proseek Multiplex Inflammation I kit. Serum profiles of inflammatory proteins in patients after aHSCT were substantially different from those observed in control subjects and related to underlying disease status before transplantation. Particularly, the difference between aHSCT patients and controls reached significance level for 57 analytes (40 upregulated, 17 downregulated in aHSCT patients). The concentration of several markers was associated with the level of donor/recipient HLA match (TGF-α: p corr = 0.025, HGF: p corr = 0.036) and with complete donor chimerism at day +30 after allografting (DNER: p corr = 0.042). None of the markers was significantly associated with acute and chronic GvHD after correction. More than half of investigated proteins significantly differed between the samples from aHSCT patients and healthy control subjects as a consequence of the "cytokine storm" after aHSCT. Comparisons of patient's subgroups based on specific biological/clinical parameters revealed much less evident differences; nevertheless, we nominated several markers associated with the level of donor/recipient HLA match and post-transplant chimerism.