Use of DPB1 T-cell epitope algorithm among italian transplant centers: A survey on behalf of Associazione Italiana di Immunogenetica e Biologia dei Trapianti

The HLA-DPB1 locus has been demonstrated to have a significant role on patients' outcome after allogeneic HSCT, and the so-called T-cell epitope (TCE) algorithm has been incorporated in international guidelines for the selection of unrelated donors. The purpose of the present study is to measure, through a national survey conducted on behalf of the Associazione Italiana di Immunogenetica e Biologia dei Trapianti (AIBT), the extent of awareness and use of HLA-DPB1 TCE-based algorithms during the donor search. 89% of the HLA laboratories answered to a short questionnaire and the results showed a progressive increase of the laboratories typing DPB1 in patients and their potential donors during the search (from 44% to 79% during the 2010-2019 period) as well as the application of a TCE-based algorithm for the donor choice whenever possible (from 24% to 65% during the same period). The DP-permissiveness status is detailed in the official HLA typing report by 12%, 32% and 50% of laboratories in 2010, 2015 and 2019, respectively. The present data indicate an encouraging raise in the awareness of the HLA-DPB1 role in unrelated donor selection; noteworthy, mentioning the TCE-based permissiveness status in the HLA typing report of each potential unrelated donor represents a notable mean to raise awareness among transplant physicians and to support them in their task of choosing the best donor. Nonetheless, despite the compelling evidence of the predictive ability of TCE-based algorithms, further efforts are still needed to extend its application to all transplant centers in Italy.

Characterization of the novel HLA-C*16:97 allele in an Italian bone marrow donor

The HLA-C*16:97 allele differs from HLA-C*16:01:01:01 at position 666 of exon 4.

The distribution of KIR-HLA functional blocks is different from north to south of Italy

The killer cell immunoglobulin-like receptor (KIR)-human leukocyte antigen (HLA) interaction represents an example of genetic epistasis, where the concomitant presence of specific genes or alleles encoding receptor-ligand units is necessary for the activity of natural killer (NK) cells. Although KIR and HLA genes segregate independently, they co-evolved under environmental pressures to maintain particular KIR-HLA functional blocks for species survival. We investigated, in 270 Italian healthy individuals, the distribution of KIR and HLA polymorphisms in three climatic areas (from cold north to warm south), to verify their possible geographical stratification. We analyzed the presence of 13 KIR genes and genotyped KIR ligands belonging to HLA class I: HLA-C, HLA-B and HLA-A. We did not observe any genetic stratification for KIR genes and HLA-C ligands in Italy. By contrast, in a north-to-south direction, we found a decreasing trend for the HLA-A3 and HLA-A11 ligands (P = 0.012) and an increasing trend for the HLA-B ligands carrying the Bw4 epitope (P = 0.0003) and the Bw4 Ile80 epitope (P = 0.0005). The HLA-A and HLA-B KIR ligands were in negative linkage disequilibrium (correlation coefficient -0.1211), possibly as a consequence of their similar function in inhibiting NK cells. The distribution of the KIR-HLA functional blocks was different along Italy, as we observed a north-to-south ascending trend for KIR3DL1, when coupled with HLA-B Bw4 ligands (P = 0.0067) and with HLA-B Bw4 Ile80 (P = 0.0027), and a descending trend for KIR3DL2 when coupled with HLA-A3 and HLA-A11 ligands (P = 0.0044). Overall, people from South Italy preferentially use the KIR3DL1-HLA-B Bw4 functional unit, while those from the North Italy equally use both the KIR3DL2-HLA-A3/A11 and the KIR3DL1-HLA-B Bw4 functional units to fight infections. Thus, only KIR3DL receptors, which exert the unique role of microbial sensors through the specific D0 domain, and their cognate HLA-A and HLA-B ligands are selectively pressured in Italy according to geographical north-to-south distribution.

A new HLA allele, HLA-B*08:122, described in an unrelated donor of Caucasian origin

A new human leukocyte antigen-B allele was found in an unrelated Italian donor.

Identification of a novel HLA-C*08 variant allele, C*08:31. Sequence analysis from exons 1 through 8

A novel allele, HLA- C*08:31 has been identified by sequence based typing in an Italian hematological patient undergoing bone marrow transplantation.

Characterization of a novel HLA-A*11 allele in a cord blood unit by sequence-based typing: HLA-A*1141

The new allele HLA-A*1141 differs from HLA-A*110101 at the codon 120 by a substitution at the first nucleotide (GGC to CGC).

The human leucocyte antigen-G 14-basepair polymorphism correlates with graft-versus-host disease in unrelated bone marrow transplantation for thalassaemia

The presence of the 14-bp insertion polymorphism of the human leucocyte antigen (HLA)-G gene (HLA-G) promotes immune tolerance through increased synthesis of HLA-G molecules. We investigated this polymorphism in a large cohort of 53 thalassaemia patients transplanted from an unrelated donor. Sixteen patients (30.2%) homozygous for the 14-bp deletion had a higher risk of developing acute graft-versus-host disease (aGvHD) than patients homozygous for the 14-bp insertion (-14-bp/-14-bp vs +14-bp/+14-bp: Relative Risk = 15.0; 95% confidence interval 1.59-141.24; P = 0.008). Therefore, the 14-bp polymorphism could be an important predictive factor for aGvHD following bone marrow transplantation.

Characterization of the novel allele HLA-Cw*0331 by sequence-based typing

A novel allele HLA-C allele, Cw*0331, has been identified by sequence based typing in a German individual selected as a potential bone marrow unrelated donor.

Distribution of killer cell immunoglobulin-like receptors genes in the Italian Caucasian population

Background

Killer cell immunoglobulin-like receptors (KIRs) are a family of inhibitory and activatory receptors that are expressed by most natural killer (NK) cells. The KIR gene family is polymorphic: genomic diversity is achieved through differences in gene content and allelic polymorphism. The number of KIR loci has been reported to vary among individuals, resulting in different KIR haplotypes. In this study we report the genotypic structure of KIRs in 217 unrelated healthy Italian individuals from 22 immunogenetics laboratories, located in the northern, central and southern regions of Italy.

Methods

Two hundred and seventeen DNA samples were studied by a low resolution PCR-SSP kit designed to identify all KIR genes.

Results

All 17 KIR genes were observed in the population with different frequencies than other Caucasian and non-Caucasian populations; framework genes KIR3DL3, KIR3DP1, KIR2DL4 and KIR3DL2 were present in all individuals. Sixty-five different profiles were found in this Italian population study. Haplotype A remains the most prevalent and genotype 1, with a frequency of 28.5%, is the most commonly observed in the Italian population.

Conclusion

The Italian Caucasian population shows polymorphism of the KIR gene family like other Caucasian and non-Caucasian populations. Although 64 genotypes have been observed, genotype 1 remains the most frequent as already observed in other populations. Such knowledge of the KIR gene distribution in populations is very useful in the study of associations with diseases and in selection of donors for haploidentical bone marrow transplantation.

Unrelated bone marrow transplantation for beta-thalassemia patients: The experience of the Italian Bone Marrow Transplant Group

Bone marrow transplantation (BMT) remains the only potentially curative treatment for patients with thalassemia major. However, most candidates for BMT do not have a suitable family donor. In order to evaluate whether BMT from an HLA-matched unrelated volunteer donor can offer a probability of cure comparable to that obtained when the donor is a compatible sibling, we carried out a study involving 68 thalassemia patients transplanted in six Italian BMT Centers. Thirty-three males and 35 females (age range, 2-37 years; median age, 15) were transplanted from unrelated volunteer donors, all selected using high-resolution molecular typing of both HLA class I and II loci. Fourteen patients were classified in risk class 1; 16 in risk class 2; and 38 in risk class III of the Pesaro classification system. Nine patients (13%) had either primary or secondary graft failure. Fourteen patients (20%) died from transplant-related causes. Grade II-IV acute graft-versus-host disease (GVHD) developed in 24 cases (40%), and chronic GVHD in 10 cases (18%). Overall survival (OS) in the cohort of 68 patients was 79.3% (CI 67-88%), whereas the Kaplan-Meier estimates of disease-free survival (DFS) with transfusion independence was 65.8% (CI 54-77%). In the group of 30 thalassemic patients in risk classes 1 and 2, the probability of OS and DFS were 96.7% (CI 90-100%) and 80.0% (CI 65-94%), respectively, whereas in the 38 patients in class 3 OS was 65.2% (CI 49-80%) and DFS was 54.5% (CI 38-70%). These data show that when donor selection is based on stringent compatibility criteria, the results of unrelated transplantation in thalassemia patients are comparable to those obtained when the donor is a compatible sibling.

New approach for bone marrow transplantation in patients with class 3 thalassemia aged younger than 17 years

When prepared for transplantation with busulfan (BU) 14 mg/kg and cyclophosphamide (CY) 120 to 160 mg/kg, patients with thalassemia in risk class 3, aged younger than 17 years, who receive transplants from HLA-identical donors, had a 30% incidence of transplant rejection with recurrence of thalassemia. This, relatively poor, outcome was ascribed to insufficient immune suppression or to inadequate eradication of the thalassemic marrow, or both. In an attempt to enhance both immune suppression and eradication of the thalassemic clones, hydroxyurea, azathioprine, and fludarabine were added to the BU and CY. This regimen, called protocol 26, was applied to 33 consecutive patients with class 3 thalassemia aged younger than 17 years and was well tolerated with 93% survival. The incidence of recurrent thalassemia after the transplantation decreased from 30% to 8%.

A new HLA-DRB1*11 allele, DRB1*1144, identified by cloning and sequencing

We report here the identification of a novel DRB1*11 allele, DRB1*1144, identified during sequence-based HLA-DRB1 typing. Molecular cloning and direct sequencing confirmed that the new allele is identical to DRB1*110401 at exon 2, except for a single nucleotide substitution (GTG-->GCG) changing codon 38 from Valine to Alanine.

Recipient mHag-HA1 disparity and aGVHD in thalassemic-transplanted patients

In order to determine the influence of HA-1 minor histocompatibility antigen mismatch on BMT outcome, we analyzed a pool of 94 thalassemic transplanted patients all selected for the presence of HLA-A(*)0201 allele. The HA-1 typing was performed using SSP analysis. All the patients received bone marrow from HLA-identical MLC nonresponsive siblings. As graft-versus-host-disease (GVHD) prophylaxis, all patients received cyclosporin and short methotrexate. Grades II-IV GVHD occurred in five (33.3%) of the 15 patients with recipient HA-1 disparity compared with 14 (17.7%) of the 79 patients without HA-1 disparity. Despite the higher incidence of acute graft-versus-host-disease (aGVHD) in the group of patients with HA-1 incompatibility, these data were not statistically significant. However, it was interesting to observe that no GVHD developed in any of the 15 cases in which the recipient was HA-1 negative and the donor HA-1 positive.

A novel HLA-A*02 allele, A*02202, identified by nucleotide sequencing

In this paper we report the identification of a new HLA-A*02 allele in two members of an Afghan family. This novel allele, designed as A*02202, differs from A*02201 by a silent substitution at codon 66 (AAC-->AAT) in the alpha1 domain. A*02202 appears to be the result of a novel mutation (Note).

Long-term survival of ex-thalassemic patients with persistent mixed chimerism after bone marrow transplantation

Twenty-six transplanted thalassemic patients out of 295 analyzed, showed the presence of persistent mixed chimerism, over a period of time varying between 2 and 11 years after BMT. Despite the presence of large numbers of residual host cells, these transplanted thalassemic patients no longer require red blood cell transfusions and have a functional graft, producing sufficient levels of hemoglobin A ranging from 8.3-14.7 g/dl. These ex-thalassemic patients with persistent mixed chimerism, although they did not achieve complete donor engraftment are no longer exposed to the risk of graft rejection. The mechanisms underlying this apparent state of tolerance or education in these patients are at the present time unknown. However, these observations may be useful for physicians involved in defining optimal strategies for clinical gene therapy, in utero hematopoietic stem cell transplantation and adoption of less toxic conditioning regimens in mini-transplantation.

Bone marrow transplantation from alternative donors for thalassemia: HLA-phenotypically identical relative and HLA-nonidentical sibling or parent transplants

Twenty-nine patients with thalassemia and a median age of 6 years (range 1.1-33 years) were given a BMT from an alternative donor. Six of the 29 donors were HLA-phenotypically identical and two were mismatched relatives, 13 were mismatched siblings and eight were mismatched parents. Six patients received no antigen (relatives), 15 patients one antigen, five patients two antigen and three patients three antigen disparate grafts. Twenty-three patients were in class 2 or class 3, whereas six patients were in class 1. Thirteen patients were given BUCY, nine patients BUCY plus ALG, six patients BUCY plus TBI or TLI and one patient BUCY with prior cytoreductive-immunosuppressive treatment as conditioning. As GVHD prophylaxis four patients received MTX, 22 CsA + MTX + methylprednisolone (MP) and three patients CsA + MP. Thirteen of 29 patients (44.8%) had sustained engraftment. The probability of graft failure or rejection was 55%. There were no significant differences between antigen disparities and graft failure. The incidence of grade II-IV acute GVHD was 47.3% and chronic GVHD was 37.5%. The incidence of acute GVHD was higher in patients receiving one or two antigen disparate in the GVHD direction grafts (vs no antigen) (P EQ 0.04; odds ratio 10.8; 95% CI 1.5-115). The probability of overall and event-free survival was 65% and 21%, respectively, with median follow-up of 7.5 years (range 0.6-17 years) for surviving patients. The degree of HLA disparity between patient and donor did not have a significant effect on survival. The incidence of nonhematologic toxicity was low. Transplant-related mortality was 34%. GVHD (acute or chronic) was a major contributing cause of death (50%) followed by infections (30%). We conclude that at present, due to high graft failure and GVHD rates, BMT from alternative donors should be restricted to patients who have poor life expectancies because they cannot receive adequate conventional treatment or because of alloimmunization to minor blood antigens.

Coexistence of two functioning T-cell repertoires in healthy ex-thalassemics bearing a persistent mixed chimerism years after bone marrow transplantation

Bone marrow transplantation (BMT) from an HLA-identical donor is an established therapy to cure homozygous beta-thalassemia. Approximately 10% of thalassemic patients developed a persistent mixed chimerism (PMC) after BMT characterized by stable coexistence of host and donor cells in all hematopoietic compartments. Interestingly, in the erythrocytic lineage, close to normal levels of hemoglobin can be observed in the absence of complete donor engraftment. In the lymphocytic lineage, the striking feature is the coexistence of immune cells. This implies a state of tolerance or anergy, raising the issue of immunocompetence of the host. To understand the state of the T cells in PMC, repertoire analysis and functional studies were performed on cells from 3 ex-thalassemics. Repertoire analysis showed a profound skewing. This was due to an expansion of some T cells and not to a collapse of the repertoire, because phytohemagglutinin stimulation showed the presence of a complex repertoire. The immunocompetence of the chimeric immune systems was further established by showing responses to alloantigens and recall antigens in vitro. Both host and donor lymphocytes were observed in the cultures. These data suggest that the expanded T cells play a role in specific tolerance while allowing a normal immune status in these patients.

An unusual DRB1*1503 haplotype without a detectable DRB5 locus in a black African family

A DRB1*1503 allele not associated with DRB5 locus has been detected in an African family during routine HLA typing for bone marrow transplantation. PCR/SSOP analysis showed the DR2-associated alleles in all the family members but the DRB5 locus appeared to be absent in the patient and his brother. The samples were then analyzed for the presence of DRB6 pseudogenes and we found that the unusual haplotype was associated with DRB6*0101 allele. This finding strengthen the hypothesis of a recombination hot spot between DRB1 and DRB6 genes.

Persistence of mixed chimerism in patients transplanted for the treatment of thalassemia

Molecular genetic techniques permit sensitive assessment of host hematopoiesis after marrow transplantation for thalassemia. Information on this persistence and the cell lines in which it occurs may permit therapeutic intervention in patients at high risk for rejection and/or relapse. The objective of this study, therefore, was to determine the evolution and cell line distribution of persistent mixed chimerism detected in 55 patients treated for beta thalassemia. Our findings indicated that rejection occurred in 20 patients, the host component disappeared in 20, and mixed chimerism without transfusion need persisted for 1 to 7 years in 15. In three patients with stable mixed chimerism for 4, 5, and 7 years, host hematopoiesis fluctuated between 25% and 75%. Despite this, donor pattern beta-globin chain synthesis maintained hemoglobin levels between 10 and 13.5 g/dL without transfusion. In these three patients, the polymerase chain reaction of the VNTR and the fluorescent in situ hybridization analysis revealed the coexistence of donor and host cells in the different peripheral blood cell subpopulations and precursors studied (CD2+, CD4+, CD8+, and CD19+ granulocytes; glycophorin-A+, erythroid burst-forming units, CD33+, granulocyte-macrophage colony-forming units). We found that rejection and disease recurrence occur in approximately one third of patients with early mixed chimerism. High levels of host type hematopoiesis can be present in patients not requiring transfusion.

Marrow transplantation for patients with thalassemia: results in class 3 patients

Thalassemia patients can be categorized as class 1 (minimal liver damage and iron overload), class 3 (extensive liver damage from iron overload), and class 2 (intermediate). These categories are prognostic for treatment outcome after marrow transplantation. Class 3 patients have more transplant-related mortality than other patients. This study examines transplantation outcome for class 3 patients. Records were reviewed of 215 patients in class 3 who received transplants in Pesaro from HLA-identical related donors between May 1, 1984 and May 1, 1994. The influence of pretransplant, peritransplant, and posttransplant variables on survival, relapse, and transplant-related mortality was examined by product-limit and proportional-hazards multivariate analysis. Age and conditioning regimen were influential on survival, and regimens with less than 200 mg/kg cyclosporine (CY) were associated with 5-year survival probabilities of .74 and .63 patients younger than 17 years and older patients, respectively. Transfusion history and regimen were influential on rejection with 5 year probabilities of .53 and .24 in patients who received less than or greater than 100 red blood cell transfusions before transplantation and regimens containing less than 200 mg/kg CY. Results of transplantation for patients with advanced thalassemia treatment have improved with the introduction of conditioning regimens with less CY. This has been associated with an increase in rejection (particularly in patients who have received < 100 red blood cell transfusions before transplant). Efforts at reducing the rejection rate by modifying the conditioning regimen should be concentrated on younger patients who have received a small number of transfusions. Patients with thalassemia who have HLA-identical family members should be transplanted before they are in class 3.

Elevated interleukin-8 serum concentrations in beta-thalassemia and graft-versus-host disease

Neutrophil chemotactic and functional defects occur in beta-thalassemia and in patients after bone marrow transplantation (BMT). Interleukin-8 (IL-8) is a novel chemotactic and activating peptide for neutrophils and can be detected in the circulation. IL-8 serum concentrations were evaluated in 30 beta-thalassemic patients before and after BMT. Serial samples from 16 patients were also studied. Fourteen sera from healthy children, 43 patients with chronic viral hepatitis, 16 patients on chronic transfusion treatment for various hematologic disorders, and 28 healthy adults were studied as controls. IL-8 was evaluated by an enzyme-linked immunosorbent assay. Patients with beta-thalassemia had higher IL-8 concentrations than did normal controls, patients with liver disease, and patients on chronic transfusion. beta-Thalassemic patients with severe liver siderosis and fibrosis had the highest IL-8 concentrations. After BMT in patients with successful engraftment, IL-8 concentrations decreased significantly. In contrast, in patients with acute graft-versus-host disease (GVHD), IL-8 concentrations were not statistically different from the concentrations found before BMT and were higher than in patients with no complications and patients with graft rejection. IL-8 may play a part in the immune dysregulation that occurs in beta-thalassemia and may be involved in the immune mechanisms leading to GVHD.

Mixed chimerism in thalassemic patients after bone marrow transplantation

Seventy-four patients with homozygous beta-thalassemia who underwent allogeneic bone marrow transplantation (BMT) were analysed in order to evaluate the incidence and the significance of mixed chimerism (MC). Using a panel of four single locus specific minisatellite DNA probes, MC was found in 36.5%, 34.7% and 16.7% of the patients at 2, 6 and 12 months respectively after BMT. Moreover we found that different pretransplant conditioning regimens could be responsible for variations in the incidence of MC. The level of residual host cells found 2 months after BMT correlated with the occurrence of rejection.

Serum amyloid A protein concentration in bone marrow transplantation for beta thalassaemia

AIMS

To investigate whether serum amyloid A protein (SAA) and C-reactive protein (CRP) concentrations could be used in the management of beta thalassaemic patients undergoing bone marrow transplantation (BMT).

METHODS

Serum SAA and CRP concentrations were determined in paired samples from 66 patients with beta thalassaemia before and after BMT. Serum SAA concentrations were determined by an enzyme linked immunoassay (EIA); serum CRP concentrations were determined by a nephelometric assay.

RESULTS

Serum SAA concentrations before transplantation were significantly higher in the group that subsequently rejected the transplant than the group without complications. SAA concentrations increased after BMT in acute graft versus host disease (GvHD) and rejection. No significant increase in SAA or CRP was found in chronic GvHD. Increases in serum in SAA and CRP concentrations were not related to concomitant infection episodes.

CONCLUSIONS

The different acute phase response in acute GvHD and rejection compared with chronic GvHD suggests that different immunopathogenic mechanisms are responsible.

Increased serum concentrations of tumour necrosis factor in beta thalassaemia: effect of bone marrow transplantation

AIMS

Serum concentrations of tumour necrosis factor-alpha (TNF) were determined in beta thalassemic patients before and after bone marrow transplantation (BMT) to evaluate whether changes in TNF concentrations after BMT were related to immune mediated complications.

METHODS

Serum TNF concentrations were determined by enzyme linked immunoassay (EIA) in paired samples from 71 patients with beta thalassemia before and after BMT. Serial samples from 13 patients were also studied for up to six months after BMT. Forty one normal healthy children matched for sex and age were studied as controls.

RESULTS

beta thalassemic patients had high serum TNF concentrations before transplantation compared with controls. These were not related to sex, age, duration of disease, number of blood transfusions, transferrin concentrations or splenectomy. DQw1 positive patients showed significantly lower TNF concentrations than non-DQw1 cases. Patients with severe liver fibrosis had significantly higher TNF concentrations. No correlation was found between TNF values and BMT outcome before transplantation but TNF alpha values fell significantly after BMT. The decrease persisted only in patients with successful engraftment. In serial samples studied for up to six months after BMT, TNF values decreased but in four out of five patients with graft rejection and in all five with acute graft versus host disease (GVHD) sharp increases occurred at the time of clinical symptoms. No correlation was found between the degree of GVHD and serum TNF-alpha concentrations nor between TNF-alpha concentrations after BMT and the presence of bacterial, viral, and fungal infections.

CONCLUSIONS

About 50% of beta thalassemic patients have increased serum TNF, and the changes after BMT are related to the occurrence of immune mediate complications. The persistence of low TNF concentrations after successful engraftment may be due to the preparative regimen and the lack of adverse immune reactions.

Molecular analysis of HLA class II antigens in bone marrow transplanted thalassemic patients

BACKGROUND

In this work we investigated whether serologically HLA class II compatible donor-recipient pairs showed differences in restriction fragment length patterns, and whether there is a correlation between the genomic differences observed and the incidence of rejection and acute graft versus host disease (GVHD).

METHODS

High molecular weight DNA was extracted from thirty-three transplanted thalassemic patients and from their genotypically HLA identical donors. The DNA was digested with TaqI and PstI restriction enzymes, separated by horizontal electrophoresis and transferred onto nylon filters.

RESULTS

Differences at the molecular level were observed in only one patient, who rejected the transplant respect to his donor when DNA was digested with the TaqI restriction enzyme and hybridized with DPB cDNA probe.

CONCLUSIONS

Although the molecular analysis revealed a difference between a patient who rejected the transplant and his donor, the RFLP typing confirmed the serological identity of the HLA class II antigens in all the other donor-recipient pairs studied.

HLA compatibility for patients with thalassemia: implications for bone marrow transplantation

In order to evaluate the possibility of a patient with thalassemia finding an HLA-identical sibling donor, we performed an analysis of HLA antigens in families of thalassemic patients. The pattern distribution was not significantly different from the expected ratio 25:50:25. When the siblings were subdivided according to the age of the patients (under or over 5 years), the above pattern remained unmodified for both the age groups. The average size of the 129 thalassemic families was 2.4. Thus, taking into account that thalassemic patients have an average of 1.4 siblings and that the HLA genotype distribution is expected as such, HLA-matched siblings are available for 33% of the patients. Because an additional 8.5% of the patients were found HLA-phenotypically identical to one parent, the chance for a patient with thalassemia to find a suitable donor for bone marrow transplantation would be increased to 41.5%. Our preliminary data cannot be extrapolated to the overall Italian thalassemic population; however, it can be inferred that for a patient with thalassemia, the chance of finding a suitable donor for bone marrow transplantation is not reduced.

An attempt to obtain a specific antiserum for in vitro immunological conditioning of bone marrow in acute non-lymphoblastic leukemia

An antiserum was produced in rabbits to acute undifferentiated leukemia (AUL) antigens. Partial absorption of the antiserum allowed the removal of the cytotoxic activity against normal mononuclear cells of peripheral blood and bone marrow, in contrast to blast cells from acute and chronic leukemias, which were killed by the antiserum in a standard NIH cytotoxicity test. These observations suggest that antigens present on blast cells of AUL are also expressed on some acute and chronic leukemic cells and that these antigens could be interpreted as B or leukemia-associated antigens because of the disappearance of all cytotoxic activity of the immune serum after extensive absorption with B cells from chronic lymphoid leukemia.