Avraham Amar

Molecular analysis of HLA class II polymorphisms among different ethnic groups in Israel

The Jewish population in Israel comprises of inhabitants of heterogeneous ethnic backgrounds. Genetic studies classify the Israeli Jewish population into two major groups: Ashkenazi from Central and Eastern Europe and Sephardic or non Ashkenazi, from the Mediterranean and North Africa. The present study was aimed at elucidating the differential influx of HLA class II alleles in Ashkenazi, in various non-Ashkenazi subgroups and in Israeli Moslem Arabs. Using the PCR-SSOP technique, a large number of alleles were detected at each of the loci examined (DRB1, DQA1 and DQB1). In addition, gene frequencies, characteristic DR/DQ linkage disequilibria, population distance and their corresponding dendogram, were used to study the relationship between Israelis as a group, non Jewish Caucasians and Blacks. These populations could be grouped into three main clusters: the first consists of all the Israeli groups with the exception of the Ethiopian Jews; the second consists of non Jewish Caucasians, with a clear distinction seen between Israelis and non Jewish Europeans and U.S. Caucasians; the third, composed of Blacks, is distinctly different from the other populations. Ethiopian Jews were found to be closer to the Blacks than to any of the Israeli Jewish groups. We have shown that Jews share common features, a fact that points to a common ancestry. A certain degree of admixture with their pre-immigration neighbors exists despite the cultural and religious constraints against intermarriage.

Donor lymphocyte infusions to displace residual host hematopoietic cells after allogeneic bone marrow transplantation for β-thalassemia major

PURPOSE Donor lymphocyte infusion (DLI) was used to reverse relapse after allogeneic bone marrow transplantation (BMT) in a patient with beta-thalassemia major. PATIENTS AND METHODS The patient with unstable mixed chimerism after BMT was treated with graded increments of donor lymphocytes (10(5) T cells/kg to 5 x 10(7) T cells/kg) to displace residual hematopoietic host cells. RESULTS DLI resulted in complete donor-derived reconstitution of the hematopoietic compartment. The patient developed mild graft-versus-host disease (GVHD) that could be controlled by steroid treatment. CONCLUSIONS This case report shows that DLI can effectively eradicate host stem cells in mixed chimeras after BMT in nonmalignant hematopoietic diseases.

Maternal-paternal histocompatibility: lack of association with habitual abortions*

Class I human leukocyte antigens (HLA-A, -B) and class II (HLA-DR) antigens were determined in 60 and 30 carefully selected couples with multiple abortions, respectively. The study group was compared with fertile couples with no history of abortion and with a control group consisting of randomly matched women and men from our laboratory cell panel. No significant deviation from the calculated control mating frequencies was observed in the group with habitual abortions. When the study and control couples were grouped by ethnic origin into Ashkenazim and non-Ashkenazim, the frequencies of shared HLA-A, -B, and -DR antigens were similar in both groups. These results do not confirm the observations of greater HLA compatibility between partners of aborting couples reported by other laboratories. Moreover, the results of an informative family in which the woman, after three consecutive spontaneous abortions, conceived and bore a healthy male infant genotypically HLA-identical to his mother are presented. Taken together, these results challenge the concept that compatibility in determinants of the major histocompatibility complex have a major role in habitual abortions.

Graft-versus-lymphoma effect after allogeneic peripheral blood stem cell transplantation for primary central nervous system lymphoma.

Allogeneic peripheral blood stem cell transplantation (allo PBSCT) is a recognized treatment modality for hematological malignancies resistant to conventional chemoradiotherapy. The post-transplant immune-mediated graft-versus-leukemia effect has major curative potential. In this case presentation, the allogeneic approach to resistant recurrent primary central nervous system (CNS) lymphoma using peripheral blood stem cells from an HLA identical sibling after immuno-suppressive non-myeloablative conditioning, was examined clinically. The patient in question had relapsing refractory primary CNS lymphoma and is the first to be treated with this modality. She developed early skin and liver-localized grade II graft-versus-host disease after allo PBSCT, which then responded to short-term treatment. Chimeric studies at the time showed 100% donor cells and repeated magnetic resonance imaging of the brain revealed gradual shrinkage of the tumor. Three months after transplant the cerebral mass was no longer evident and currently, 30 months after transplantation, the patient continues to be disease free. The absence of any signs of malignancy suggests the development of a durable graft-versus-lymphoma effect in this brain tumor and indicates that this effect may be achieved even after non-myeloablative conditioning.

An association between clozapine-induced agranulocytosis in schizophrenics and HLA-DQB1*0201.

A group of 18 Israeli, clozapine-treated, schizophrenia patients underwent molecular and serological HLA typing in order to determine whether the major histocompatibility complex is associated with the development of clozapine-induced agranulocytosis. While under treatment with clozapine, 2 of the 18 patients developed agranulocytosis (total white blood cell count <3000/mm(3) and absolute polymorphonuclear count <500/mm(3)) and 3 developed granulocytopenia (total white blood cell count <3500/mm(3) and absolute polymorphonuclear count <1000/mm(3)). HLA-DQB1*0201 was present in all five patients who developed agranulocytosis or granulocytopenia (5/5; 100%), but in only 54% (7/13) of the patients who did not develop those complications. These findings indicate that DQB1*0201 or a gene located nearby could be involved in clozapine-induced agranulocytosis.

Allogeneic cell-mediated and cytokine-activated immunotherapy for malignant lymphoma at the stage of minimal residual disease after autologous stem cell transplantation

Immunocompetent donor-derived T lymphocytes play a crucial role in the elimination of residual leukemic cells post allogeneic bone marrow transplantation. Because this graft versus leukemia (GVL) effect is absent after autologous stem cell transplantation (ASCT), a high rate of relapse ensues. We introduced cell-mediated immunotherapy at the stage of minimal residual disease in lymphoma patients to help effect a GVL-like reaction by adoptive transfer of immunocompetent human leukocyte antigen-matched donor peripheral blood lymphocytes (PBL). Thirteen consecutive patients with high-risk lymphoma were treated with allogeneic cell therapy (AlloCT) after having undergone ASCT. In the absence of graft-versus-host disease, cell therapy-induced graft-versus-lymphoma reaction was amplified by human recombinant interleukin 2 (rlL-2) during 3 days to activate donor PBL in vivo, followed by infusion of in vitro rlL-2 activated donor lymphocytes combined with 3-day rlL-2 therapy. Nine of the patients underwent the treatment protocol well. In the four other patients, in whom the AlloCT resulted in marrow aplasia due to elimination of host hematopoietic cells, treatment with donor marrow cell infusion without further conditioning was performed. Adoptive cell therapy in the form of AlloCT may turn out to be an effective therapeutic modality for the treatment of resistant residual disease in lymphoma patients.

Familial gonadal germinative failure: endocrine and human leukocyte antigen studies

Two primary amenorrheic sisters were diagnosed as 46,XX pure gonadal dysgenesis. Their brother, a normal phenotypic and genotypic male, was azoospermic due to primary germinative failure. Parental consanguinity was observed, suggesting an autosomal recessive inheritance. This is the first reported family in which both an otherwise healthy male and two females were affected by gonadal germinative failure. Endocrine studies showed impaired gonadal function in the three affected siblings. The two females with gonadal dysgenesis and the azoospermic male shared one human leukocyte antigen haplotype; the second haplotype, however, was different. The common haplotype was also found in the oligomenorrheic sister whose gonadotropin-releasing hormone test was compatible with normal ovarian function, in the mother, and in one of her offspring who had a normal spermiogram. Hence, linkage between human leukocyte antigens and gonadal failure in this family had been excluded. The possible etiology of familial, chromosomally competent, gonadal failure is discussed.

Genetics of insulin dependent diabetes mellitus in Israel: Population and family study

The association between insulin dependent diabetes mellitus (IDDM) and the HLA system was studied in two groups of Jewish patients: 50 Ashkenazim and 42 non-Ashkenazim. The pattern of association of HLA-A and B locus antigens was somewhat different from that observed in European Caucasian patients. HLA-B8 had a higher frequency; B15 and Cw3 were rare in the population studied and were less frequent in IDDM patients than in controls. On the other hand, the frequency of A26, B18, and Bw38 was increased in Ashkenazi patients, but not in non-Ashkenazim, who in turn showed an increase for Bw51. Although the association between IDDM and HLA-A and B locus antigens shows a marked variability in different populations, the association with HLA-DR3 and DR4 is constant feature. There was a typical excess of DR3/DR4 heterozygotes in both patient groups. This heterozygote type carries the highest relative risk, followed by DR4/DR4 homozygotes. These data can well be interpreted by a model of two different HLA-linked susceptibility genes, one associated with DR3 and the other one with DR4, that interact so that different genotypes are associated with different levels of penetrance. This model received further support from studies in 15 multiple case families where there is an excess of affected sib pairs sharing two DR antigens.

HLA-DR,D recombination in a kidney transplant recipient

Immunogenetic studies of a consanguineous family revealed discordance in the inheritance pattern of the HLA-D and HLA-DR antigens in one offspring. The findings suggest a recombination between the HLA-D and HLA-DR loci in one of the paternal chromosomes. Results on segregation of B-cell alloantigens. MLC reactivity, and glyoxalase isoenzyme determination map the DR gene between the HLA-B and D loci.

Successful cell-mediated cytokine-activated immunotherapy for relapsed acute myeloid leukemia after hematopoietic stem cell transplantation

Acute myeloid leukemia (AML) is an extremely aggressive disease with a high relapse rate even after allogeneic hematopoietic stem cell transplantation (HSCT). We report the successful outcome of cell‐mediated cytokine‐activated immunotherapy in a high‐risk pediatric AML patient who relapsed shortly after allogeneic HSCT. Donor lymphocyte infusion along with interferon induced a graft‐versus‐leukemia effect, presenting as a reversible episode of graft‐versus‐host disease, which led to stable complete donor chimerism and total eradication of AML for over 24 months, at the time of this report. The curative potential of immunotherapy in hematological malignancies is discussed. Am. J. Hematol., 2009.