A. Balas

Latent Autoimmune Hepatitis Triggered During Interferon Therapy in Patients With Chronic Hepatitis C

BACKGROUND/AIMS Interferon can induce autoantibodies and autoimmune reactions. This study reviewed the clinical, serological, and HLA phenotypical features of patients who developed autoimmune hepatitis during interferon therapy for chronic hepatitis C, analyzing their response to immunosuppressive treatment. METHODS The diagnosis of chronic hepatitis C was based on positivity for viral RNA and a liver biopsy specimen obtained before interferon treatment. Sera were tested for autoantibodies by indirect immunofluorescence assay. HLA typing was performed by applying a standard microlymphocytotoxicity method. RESULTS Of 144 patients with chronic hepatitis C treated with interferon, 7 women deteriorated during treatment; serum transaminase, gamma-globulin, and immunoglobulin G levels increased; and serum autoantibodies became positive. Interferon was interrupted, a diagnosis of autoimmune hepatitis was established, and immunosuppressive therapy was initiated. All patients responded to this treatment. The 7 patients had similar HLA typing to those with autoimmune hepatitis, with DR4 in 2 patients (67%) with type 2 autoimmune hepatitis, and with DR3 and DR52 in 2 (50%) and 4 (100%) patients, respectively, with type 1 autoimmune hepatitis; additionally, 5 patients (71%) had DQ2, and 4 (57%) had both DR52 and DQ2. CONCLUSIONS In female patients with chronic hepatitis C, a genetic susceptibility to autoimmune hepatitis may exist, possibly triggered by immunostimulating effects during interferon therapy. Immunosuppressive treatment has been well tolerated and seems to be effective.

Disparity for the minor histocompatibility antigen HA-1 is associated with an increased risk of acute graft-versus-host disease (GvHD) but it does not affect chronic GvHD incidence, disease-free survival or overall survival after allogeneic human leucocyte antigen-identical sibling donor transplantation

Disparity for the minor histocompatibility antigen HA‐1 between patient and donor has been associated with an increased risk of acute graft‐versus‐host disease (GvHD) after allogeneic human leucocyte antigen (HLA)‐identical sibling donor stem cell transplantation (SCT). However, no data concerning the impact of such disparity on chronic GvHD, relapse or overall survival are available. A retrospective multicentre study was performed on 215 HLA‐A2‐positive patients who received an HLA‐identical sibling SCT, in order to determine the differences in acute and chronic GvHD incidence on the basis of the presence or absence of the HA‐1 antigen mismatch. Disease‐free survival and overall survival were also analysed. We detected 34 patient–donor pairs mismatched for HA‐1 antigen (15·8%). Grades II–IV acute GvHD occurred in 51·6% of the HA‐1‐mismatched pairs compared with 37·1% of the non‐mismatched. The multivariate logistic regression model showed statistical significance (P: 0·035, OR: 2·96, 95% CI: 1·07–8·14). No differences were observed between the two groups for grades III–IV acute GvHD, chronic GvHD, disease‐free survival or overall survival. These results confirmed the association between HA‐1 mismatch and risk of mild acute GvHD, but HA‐1 mismatch was not associated with an increased incidence of chronic GvHD and did not affect relapse or overall survival.

Bi-directional allelic recognition of the human minor histocompatibility antigen HB-1 by cytotoxic T lymphocytes

Human minor histocompatibility antigens (mHag) are target antigens of the graft‐versus‐leukemia response observed after allogeneic HLA‐identical stem cell transplantation. We previously defined the molecular nature of the B cell lineage‐specific mHag HB‐1. The CTL epitope was identified as the decamer peptide EEKRGSLHVW presented in the context of HLA‐B44. The HB‐1 antigen is encoded by a locus of yet unknown function on chromosome 5q32. A single nucleotide polymorphism within this locus results in an amino acid change from histidine (H) to tyrosine (Y) at position P8 within the CTL epitope. Based on genomic information, we have developed a PCR‐RFLP assay to perform HB‐1 typing at the DNA level. We determined that the allelic frequency for the H and Y variant is 0.79 and 0.21, respectively. From these data, we calculated that the expected recipient disparity between HLA‐B44‐matched sibling pairs for HB‐1H is 2.8%, whereas recipient disparity for HB‐1Y is expected to be 12.4%. Therefore, we addressed whether the HB‐1Y peptide is reciprocally immunogenic. We revealed that both peptide variants bind equally efficient to HLA‐B44 molecules and that the H/Y substitution has noinfluence on formation of epitope precursor peptides by 20 S proteasome‐mediated degradation. More directly, CTL recognizing the naturally presented HB‐1Y peptide could be generated from a HB‐1H homozygous donor using peptide‐pulsed dendritic cells. Using a set of synthetic structurally related peptide variants, we found that the H/Y substitution has a major impact on TCR recognition by CTL specific for either of the HB‐1 allelic homologues. HB‐1 is the first human mHag described that induces bi‐directional allogeneic CTL responses that may contribute to a specific graft‐versus‐leukemiaresponse following allogeneic stem cell transplantation.

Allelic and haplotypic HLA frequency distribution in Spanish hematopoietic patients. Implications for unrelated donor searching

Histocompatibility criteria for unrelated donor selection are based on high-resolution definition of HLA genes. In spite of the expansion of the unrelated donor registries, HLA matching remains a problem for many patients because of the great diversity of HLA alleles and haplotypes. The availability of matched donors at an allelic level depends on the frequency of the patients alleles and haplotypes. Therefore, data regarding HLA distribution for each population are needed in order to evaluate the donor searching approach and, may be, even the therapeutic strategy. In the present report, we have analyzed 253 haematological Spanish patients awaiting unrelated haematopoietic stem cell (HSC) donors. HLA allele and haplotype frequencies have been defined at high resolution for the first time in this population. Significant differences in HLA distribution have been reported when comparing two patient groups, one that received full-match (10/10) unrelated donors and one that did not. Factors like rare alleles, presence of B*510101 (because of the association with multiple HLA-C alleles), as well as infrequent B-C and DRB1-DQB1 associations, showed a negative value for finding a suitable donor, whereas the presence of one of the six-gene haplotypes with a frequency ≥ 0.9% in our sample was a positive factor influencing donor searching. These differences will be useful in donor searching advising and in the use of different therapeutic strategies.

Transient donor cell-derived myelodysplastic syndrome with monosomy 7 after unrelated cord blood transplantation

Abstract:  Donor cell leukaemia or myelodysplastic syndromes are extremely rare complications that have been observed not only after haematopoietic transplantation with progenitor cells harvested from bone marrow and peripheral blood, but also after cord blood transplantation. We describe the early onset of monosomy 7 in donor cells after cord blood transplantation in a patient diagnosed with myelodysplastic syndrome 3 months after transplantation. Fluorescent in situ hybridisation analysis performed in a cryopreserved aliquot of the cord blood showed 2.5% of nuclei with monosomy 7. The cord blood donor was studied and he showed neither peripheral blood cytopenias nor cytological or cytogenetic features of myelodysplasia. The cell blood counts (CBC) of the girl have improved over 2 yr while decreasing the percentage of monosomic cells. The monosomic clone has finally disappeared and the CBC are finally normal. This case of transient monosomy 7 started very early after engraftment emphasises the relevance of clonal instability of specific progenitor cells in the early engraftment, and host immune status, in cytogenetic abnormalities founded in donor cell‐derived MDS and acute leukaemia. Moreover, the clinical follow‐up of this patient, recommends a more conservative treatment for this clonal disease early developed after transplantation.

Progenitor cell subsets and engraftment kinetics in children undergoing autologous peripheral blood stem cell transplantation.

The main objective of the present study was to determine the role of CD34+ cell subsets in the haemopoietic recovery of children undergoing peripheral blood stem cell transplantation. For this purpose, 38 leukaphereses from 33 children with malignancies mobilized with G‐CSF were analysed. Using dual‐colour flow cytometry, different subpopulations of CD34+ cells were quantified and the number of each reinfused subsets correlated with haemopoietic resurgence. Multivariate analysis showed that the number of CD34+CD38− cells and CD34+CD38+ cells correlated better with time to neutrophil and platelet recovery, respectively, than the total number of CD34+ cells. Threshold values for rapid haemopoietic recovery, determined by the receiver operating characteristic analysis, were found to be 0.5 × 106 CD34+CD38− cells for neutrophil engraftment, and 2.0 × 106 CD34+CD38+ cells for platelet recovery. It is suggested that the analysis of CD34+ cell subsets could increase understanding of the repopulation capacity of a given leukapheresis product in peripheral blood stem cell transplantation procedures in children. In particular, this procedure could be extremely useful when low numbers of CD34+ cells are collected.

Mesenchymal stem cells are of recipient origin in pediatric transplantations using umbilical cord blood, peripheral blood, or bone marrow.

Chimerism status of bone marrow (BM)-derived mesenchymal stem cells (MSC) from children who received an allogeneic hematopoietic transplant is an interesting question, referring not only to hematopoietic transplant but also to cellular therapy. MSC are present in the BM but it is still controversial whether these cells maintain their capacity for homing to the BM. In this report, we studied chimerism of BM-derived MSC from children who underwent a hematopoietic stem cell transplant using BM, peripheral blood, and umbilical cord blood as source of hematopoietic stem cells.

Full donor chimerism by day 30 after allogeneic peripheral blood progenitor cell transplantation is associated with a low risk of relapse in pediatric patients with hematological malignancies

Full donor chimerism by day 30 after allogeneic peripheral blood progenitor cell transplantation is associated with a low risk of relapse in pediatric patients with hematological malignancies

Allogeneic peripheral blood stem cell transplantation (PBSCT) from HLA-identical sibling donors in children with hematological diseases: a single center pilot study

Between February 1995 and July 1999 25 pediatric patients (8 months to 14 years old) underwent peripheral blood stem cell transplantation (PBSCT) from an HLA-identical sibling donor. Diagnoses included ALL (17), non-ALL (6), and non-malignant disease (2). GVHD prophylaxis consisted of cyclosporine plus methotrexate (15), only cyclosporine (8), cyclosporine plus prednisone (1), or nothing (1). All donors (6 months to 41 years old) received G-CSF at 10 μg/kg/day subcutaneously for 4–5 days and on day 5 underwent large volume leukapheresis. Median number of CD34+ and CD3+ cells collected and infused was 6.9 × 106 (range 2.5–32.8) and 4.5 × 108 (0.5–22.1) per kg of recipient body weight respectively. Median time to achieve ANC >0.5 × 109/l and platelets >20 × 109/l was 10 and 12 days, respectively. Acute GVHD grade ⩾II developed in 10 of 24 evaluable patients (42%). Probability of acute GVHD was 62%. Median time to discharge was 25 days (range 14–52). Among 20 evaluable patients, five (25%) developed chronic GVHD at day 100. Probability of chronic GVHD was 29% after 1 year post PBSC. At a median follow-up of 558 (9–2071) days, overall survival for the whole group is 68%. Probabilities of event-free survival, overall survival and relapse for patients with malignant hematological diseases are 53%, 59% and 24% at 5 years, respectively. This study has confirmed the feasibility and safety of mobilization and collection of PBSC products and the applicability of this procedure to the pediatric population, both donors and recipients. Studies including larger numbers of pediatric patients undergoing allogeneic PBSCT are warranted to determine the long-term outcomes of such procedures. Bone Marrow Transplantation (2001) 28, 537–543.

The new HLA-C allele C*07:170 shows a new polymorphism at amino acid position 147

The new human leukocyte antigen (HLA)-C allele, Cw*0220, was identified in a Spanish Caucasian patient by sequence-based typing. HLA-Cw*0220 differs from Cw*020202 by a single amino acid replacement at constant position 169 (R > H).