The effect of IgM-enriched human Ig and rabbit antithymocyte globulin on the stimulation of mononuclear cells

Whether IgM-enriched intravenous Ig (pentaglobin) is a useful adjunct treatment for graft versus host disease (GvHD) prophylaxis in allogeneic stem-cell transplantation is unclear. Clinical data with the use of a five-agent GvHD prevention regimen, including pentaglobin and antithymocyte globulin (ATG), are encouraging. In vitro both have been reported to modulate alloreactive T cells. We compared their inhibitory effect on the phytohemagglutinin-induced lymphocyte proliferation. ATG blocked the proliferation of lymphocytes at lower doses and much stronger than pentaglobin. The combination of both was not different from ATG alone. In pentaglobin, glucose used as stabiliser, caused the effect. Starting at a concentration of 40 mg/dL glucose, glucose alone showed a dose-dependent inhibition of phytohemaglutinin (PHA)-induced proliferation. For the in vivo application of pentaglobin, the results suggest that pentaglobin does not inhibit the proliferation of T cells.

Jurkat cell-reactive anti-thymocyte globulin assessed ex vivo by flow cytometry persists three weeks in circulation

Rabbit anti-thymocyte globulin (ATG-Fresenius) is a polyclonal anti-serum raised against the lymphoblastic T cell line Jurkat. It is used for in vivo depletion of host and donor T cells for allogeneic stem cell transplantation. After administration of 90 mg/kg prior to transplant, rabbit immunoglobulin G (IgG) remains present for 4-5 weeks, but it is unknown how long T cell-reactive antibodies persist. Therefore, we measured anti-Jurkat antibodies by flow cytometry. The detection limit for Jurkat-reactive antibodies was 0.1 microg/ml rabbit IgG; half-maximal labeling of Jurkat cells required 183 microg/ml rabbit ATG. The mean half-life of Jurkat-reactive antibodies in 7 patients was 4 days. Detectable levels persisted up to 3 weeks with antibody levels equivalent to 0.2-4.1 microg/ml rabbit ATG. Jurkat-reactive antibodies were eliminated two-fold faster than rabbit IgG, as assessed by enzyme-linked immunosorbent assay (ELISA). The results suggest that in patients pretreated with ATG before transplantation, residual anti T-cell antibodies may effectively modulate recovery of T cells generated after transplantation, thereby lowering the incidence of severe GVHD.

PERB11 (MIC): a polymorphic MHC gene is expressed in skin and single nucleotide polymorphisms are associated with psoriasis

The susceptibility genes for psoriasis remain to be identified. At least one of these must be in the major histocompatibility complex (MHC) to explain associations with alleles at human leucocyte antigen (HLA)-A, -B, -C, -DR, -DQ and C4. In fact, most of these alleles are components of just two ancestral haplotypes (AHs) designated 13.1 and 57.1. Although relevant MHC gene(s) could be within a region of at least 4 Mb, most studies have favoured the area near HLA-B and -C. This region contains a large number of non-HLA genes, many of which are duplicated and polymorphic. Members of one such gene family, PERB11.1 and PERB11.2, are expressed in the skin and are encoded in the region between tumour necrosis factor and HLA-B. To investigate the relationship of PERB11.1 alleles to psoriasis, sequence based typing was performed on 97 patients classified according to age of onset and family history. The frequency of the PERB11.1*06 allele is 44% in type I psoriasis but only 7% in controls (Pc = 0.003 by Fisher's exact test, two-tailed). The major determinant of this association is a single nucleotide polymorphism (SNP) within intron 4. In normal and affected skin, expression of PERB11 is mainly in the basal layer of the epidermis including ducts and follicles. PERB11 is also present in the upper keratin layers but there is relative deficiency in the intermediate layers. These findings suggest a possible role for PERB11 and other MHC genes in the pathogenesis of psoriasis.

Monitoring anti-thymocyte globulin (ATG) in bone marrow recipients

The present study was undertaken to acquire a rationale for clinical dose adjustment of anti-thymocyte globulin (ATG) to improve cost effectiveness and safety of graft-versus-host disease prophylaxis. The concentration of rabbit ATG in the serum of 12 patients was measured by ELISA and by the inhibitory effect on phytohaemagglutinin-induced blastogenesis. At 10 mg/ml ATG, 3H-thymidine incorporation was effectively blocked. Serial two-fold dilution of ATG showed that this effect decreased in a concentration-dependent manner and was lost at 10 ng/ml ATG. One hundred microlitres serum taken at day -1 to +22 post transplant effected significant inhibition of the phytohaemagglutinin-response with 49+/-12% c.p.m. (x +/- s.d.) on day +1 post transplant compared to 93+/-13% c.p.m. on day -1 (P<0.001, unpaired one-sided t-test). The rabbit-IgG was maximal at a concentration of 907+/-187 microl/ml at day 0. Subsequently, it decreased with time. While rabbit-IgG was detectable for a long period (e.g. 160 microg/ml at day +22 in patient MD), the effect on the phytohaemagglutinin-response of normal mononuclear cells lasted up to 4 days post transplant. We conclude that 90 mg/kg body weight ATG-Fresenius given prior to marrow transplant leads to sustained T cell immunosuppression post transplant.

Serological and molecular analysis of HLA class I and II alleles in Thai patients with psoriasis vulgaris

The HLA class I and class II alleles in 67 patients with type I psoriasis vulgaris, 23 patients with type II psoriasis vulgaris and 140 healthy individuals were analyzed. The frequencies of HLA-A2, -B46, -B57 and DQB1*0303 were significantly increased in type I psoriasis compared to the controls (Pc<0.05). Molecular analysis of HLA-A2 alleles showed an increase in HLA-A*0207 and a decrease in HLA-A*0203 in type I psoriasis. HLA-DQB1*0301 was significantly decreased in type I psoriasis compared to the normal controls (Pc<0.05). No association of any alleles with type II psoriasis was observed. This data demonstrated two susceptible haplotypes: HLA-A1-B57-DRB1*0701-DQA1*0201-DQB1*0303 (AH57.1) and HLA-A2-B46-DRB1*0901-DQA1*0301-DQB1*0303 (AH46.1) for type I psoriasis in the Thai population. Besides, the haplotype AH46.1 was also associated with type II psoriasis.

HLA and alveolar echinococcosis

Evidence in animal intermediate hosts that susceptibility to larval infection with Echinococcus multilocularis is restricted to individual host factors prompted us to investigate the susceptibility markers in humans. Because antigens of the extracellular parasite E. multilocularis are possibly presented by MHC molecules in a restricted way, we speculated that MHC polymorphism may influence resistance of the host towards infection and course of disease. We studied HLA-A, -B, -DRB1, -DQB1 and -DPB1 polymorphism in 151 patients with alveolar echinococcosis. Patients with an observation period of more than 2 years were grouped according to the clinical follow-up into cured (no recurrence following surgery) patients and patients with regressive or progressive forms of disease during benzimidazole chemotherapy. By comparing phenotypic frequency between patients with alveolar echinococcosis and healthy controls, HLA-DRB1*11 was associated with a reduced risk for disease development (odds ratio=0.55, 95% confidence interval=0.34-0.88; P=0.01). HLA-DQB1*02 was more frequent in patients with progressive disease when compared with patients with regressive disease (54.3% vs 28.3%, P=0.02). The result suggests that HLA-DRB1*11 might confer protection against alveolar echinococcosis and that HLA-DQB1*02 may indicate a risk for progressive disease development. The findings may facilitate the search for immunodominant T-cell epitopes of E. multilocularis.

Human monoclonal antibody with T-cell-like specificity recognizes MHC class I self-peptide presented by HLA-DR1 on activated cells

Alloreactive T cells recognize peptides presented in the binding groove of major histocompatibility complex molecules (MHCs), whereas B cells mainly recognize the MHCs independent of bound peptides. Here, we demonstrate that the human B-cell repertoire comprises B cells which can be stimulated during pregnancy to produce antibodies reacting with MHCs in a way similar to T cells. The human monoclonal antibody UL-5A1 recognizes DR1(DRA/DRB1*0101) molecules on lymphoblastoid cell lines only if they co-express HLA-A2 or if they have been loaded with HLA-A2-derived peptides. The effect of the HLA-A2 peptide 105-117 on UL-5A1 reactivity was specific, time and dose-dependent. Reactivity increased when naturally processed peptides were removed from DR1 molecules before the HLA-A2 peptide 105-117 was loaded. UL-5A1 reacted specifically with cells that had been activated. The results imply a role of activation of cells in peptide processing and/or loading.

Tumor necrosis factor-alpha gene polymorphism in psoriasis

Psoriasis, an inflammatory autoimmune disease, is characterized by increased level and activity of the proinflammatory cytokine TNF-alpha in affected lesions. Two promoter region polymorphisms of the TNF-alpha locus--one at position -308 and the other at -238--were examined in 99 Caucasian patients (64 with type I and 35 with type II psoriasis) and in 123 controls. A highly significant difference in the distribution of the -238 polymorphism--the TNF (G,A) genotypes--was detected between the type I psoriasis patients and controls: compared to the controls, the frequency of the homozygous TNF-G genotype was decreased (55 vs. 91%; p = 0.0000000274; corrected p = 0.0000001644; odds ratio = 0.12), whereas that of TNF-G,A heterozygotes was increased (41 vs. 8%; p = 0.000000264; corrected p = 0.000001584; odds ratio = 7.73) in patients. No significant differences were observed in the distribution of the TNF-A homozygotes. These results suggest that homozygosity of the G allele is associated with a lower relative risk (resistance), whereas heterozygosity at this locus is associated with an increased risk (susceptibility) of type I psoriasis.

Evidence for somatic mutation and affinity maturation of diabetes associated human autoantibodies to glutamate decarboxylase

The processes that lead to the production of islet cell autoantibodies in insulin-dependent (type 1) diabetes mellitus (IDDM) are largely unknown. Humoral autoimmunity may be the result of an antigen-independent polyclonal B cell activation, or a consequence of an antigen driven B cell activation and selection for the antigen. We have analysed the gene elements encoding the immunoglobulin variable regions of seven human monoclonal islet cell antibodies (MICA) 1-7 directed to the major islet autoantigen glutamate decarboxylase (GAD65). These autoantibodies were derived from two patients with newly diagnosed IDDM. The variable gene regions of the MICA revealed different sequences, and no relation between V gene usage and shared epitope recognition of the MICA was evident. An elevated usage of VH 1, VH 4 and Vlambda 2 gene segments was observed. The underrepresentation of VH 3 family members in the MICA discriminated them from most autoantibodies. The high relative avidities for GAD65 of MICA 1, 3, 4 and 6 and their high, nonrandom ratio of replacement versus silent mutations in the antigen binding regions indicated that the humoral response to GAD65 is driven by the antigen. MICA 2, 5 and 7 showed as well an excess of replacement mutations in the antigen binding regions, but revealed lower relative avidities for their antigen. Since these clones accumulated many somatic mutations in their variable gene regions, they may be characteristic for later stages of the autoimmune disease. The results suggest that, in humans, an antigen driven B cell activation and affinity maturation process may contribute to the production of GAD65-autoantibodies found in patients with IDDM.

Familial juvenile onset psoriasis is associated with the human leukocyte antigen (HLA) class I side of the extended haplotype Cw6-B57-DRB1*0701-DQA1*0201-DQB1*0303: a population- and family-based study

To further evaluate the nature of the HLA association with psoriasis, HLA haplotypes of 60 patients with type 1 (early onset, positive family history) and 30 patients with type II (late onset, no family history) psoriasis were investigated by polymerase chain reaction sequence-specific oligonucleotide hybridization (HLA class II) and serology (HLA class I). Ethnically matched blood donors (146) served as controls. In type I, but not type II psoriasis, the Caucasian HLA extended haplotype (EH) Cw6-B57-DRB1*0701-DQA1*0201-DQB1*0303 named according to the B allele EH-57.1 was highly significantly overrepresented (p cor= 0.00021). This particular EH was present in 35% of type I psoriatics but only 2% of controls. EH-57.1+ individuals therefore carry a 26 times higher risk of developing type I psoriasis than individuals who are EH-57.1-negative Further analysis of individual HLA alleles revealed that within EH-57.1, HLA class I antigens (Cw6-B57) were associated to a much higher extent with type I psoriasis than the HLA class II alleles (DRB1*0701-DQA1*0201-DQB1* 0303). Pedigree analysis of three multiply affected families over three generations revealed a cosegregation of disease with EH-57.1. These results strongly suggest that a gene for familial psoriasis is associated with the class I side of the extended haplotype Cw6-B57-DRB1*0701-DQA1*0201-DQB1*0303.

Characterization of two human IgM monoclonal antibodies reactive with HLA-B27

We describe here the generation and characterization of two human monoclonal IgM antibodies (UL-4F11 and UL-F6) reactive with HLA-B27. The monoclonal antibody (mAb) UL-4F11 is cytotoxic for peripheral mononuclear cells and, therefore, useful as typing reagent for HLA-B27 and HLA-B38. Protein chemistry showed that the mAb UL-4F11 precipitates HLA-B27 molecules. Epitope mapping analysis suggests that the amino acids 45, 67, 82 and 83 (alpha-1 domain) of the HLA-B27 sequence are necessary for mAb UL-4F11 reactivity. The mAb UL-F6 is suitable for complement dependent lysis of lymphoblastoid cell lines and stimulated peripheral blood mononuclear cells with HLA-B27 (B*2701, B*2702, B*2703, B*2705, B*2707), B13, B40 (60,61), B47 and B48 specificities. Its reactivity indicates that the amino acid valine in position 152 and glutamic acid in position 163 of the alpha-2 domain are crucial for the binding epitope.

Immunoglobulin variable gene analysis of human autoantibodies reveals antigen-driven immune response to glutamate decarboxylase in type 1 diabetes mellitus

Insulin-dependent (type 1) diabetes mellitus is an organ-specific autoimmune disease frequently associated with an islet-specific humoral autoimmune response. The role of islet cell autoantibodies in the disease process is unclear; in particular, it is not known whether they are a non-specific side effect of islet cell destruction or play a role in the autoimmune network leading to type 1 diabetes. Here we report the immunoglobulin gene usage and somatic mutation rates of a panel of seven human monoclonal islet cell autoantibodies (MICA 1-7) directed towards the major islet cell autoantigen glutamate decarboxylase (GAD). These autoantibodies were produced from cells from two patients with newly diagnosed type 1 diabetes. VH1, VH4 and V lambda 2 gene segments were frequently used in the MICA, but no correlation between V gene usage and epitope recognition was found. The nonrandom ratio of replacement versus silent mutations in the variable gene region, an accumulation of replacement mutations in the complementarity determining regions, which confer antigen binding, and the high relative avidity for GAD observed for MICA 1, 3, 4, and 6, suggested that the immune response to GAD is driven by the antigen. In contrast, MICA 2, 5, and 7, revealing a lower affinity for antigen, have accumulated a large number of silent mutations. These latter antibodies may, therefore, be characteristic for later stages of the chronic autoimmune disease. Our results argue in favor of an antigen-driven autoantibody response to islets in human type 1 diabetes. They suggest that GAD is an important target of autoimmunity associated with type 1 diabetes.

Analysis of TAP2 and HLA-DP gene polymorphism in psoriasis

TAP2 is a gene, located between HLA-DP and HLA-DQ, whose products form a transporter molecule involved in endogenous antigen processing. Polymorphic residues have been described in this gene. TAP2 is of particular interest because its involvement in antigen presentation makes it a candidate for a disease susceptibility gene. In psoriasis, two clinical subtypes analogous to the situation in diabetes type I with early onset and family history and type II with later onset and without family history have been described. We have previously shown that type I but not type II psoriasis is associated with the HLA-DRB1*0701/2, -DQA1*0201, -DQB1*0303 haplotype. To investigate whether this haplotype extends to include particular TAP2 and/or DP alleles, we tested the TAP2 and HLA-DP alleles of a control group (n = 199), patients with psoriasis type I (n = 66), and patients with psoriasis type II (n = 35) by hybridization with SSOs. Our data show that there is no significant correlation between TAP2 and/or HLA-DP gene polymorphism and psoriasis type I and/or type II. We conclude that disease association in type I psoriasis is associated with the extended haplotype HLA-B57, -Cw6, -DRB1*0701/2, -DQA1*0201, -DQB1*0303.

[Bone marrow transplantation]

Bone marrow transplantation from HLA-identical siblings has become an accepted therapy for leukaemia and a variety of lympho-haematopoietic disorders. In recent years the marrow of unrelated donors is increasingly used for patients lacking a family donor. In this paper current principles and methods of donor selection are presented with special regard to the search for an unrelated donor.

Semiautomated HLA-DQB1 typing by fluorescent dye photometry of amplified DNA on microtiter plates

We report a simple semiautomated HLA class II typing method that suits the demands of a 24-hour-duty transplantation service for preorgan retrieval donor typing. The procedure consists of sequence-specific amplification of HLA alleles by the polymerase chain reaction (nested PCR-SSP) followed by fluorescent dye photometry of the resulting PCR products on microtiter plates. The entire typing procedure is semiautomated and completed in less than 90 minutes after DNA isolation. The test was evaluated for the definition of the specificities DQ1-DQ9 (generic HLA-DQB1 typing). Sensitivity and specificity as judged by DNA reference typing in a different laboratory was 99.5% (n = 202 alleles).

HLA DNA preorgan retrieval donor typing in renal transplantation

For the first time, a DNA technique was used in clinical practice for pre-organ donor retrieval typing in renal transplantation. The method is based on the polymerase chain reaction with nested sequence-specific pairs (nested PCR-SSP) for all serological HLA-DR specificities of DR1-DR18. A panel of reference-typed individuals (n = 101) was investigated in a blind quality control study and the results revealed a sensitivity of 99.5% and a specificity of 100%. Semi-automation of PCR-SSP provided rapid, accurate and reliable typing results demonstrating that this DNA test is most suitable for replacing the error-prone HLA-DR serological technique. Twenty-seven consecutive cadaveric organ donors have been successfully typed so far. The results were available within less than 3 h after blood sampling and in all cases prior to the retrieval of organs. In conclusion, the introduction of this accurate DNA typing in HLA matching programs may significantly improve the graft survival rate in renal transplantation.

TAP2 gene polymorphism segregates with DR-DQ in DR/DP recombinant siblings

RING 11, a second transport-associated gene (TAP2), has been recently identified in the DR-DP interval of the human class II region. Two predominant alleles, TAP2A and TAP2B, differing by 17 amino acids at the C-terminus of the ATP-binding domain are present in the Caucasoid population at frequencies of 79% and 21%, respectively. In the rat, polymorphism of the TAP genes were found to influence peptide loading of MHC class I molecules and, in humans, it was speculated that variation in peptide loading of HLA-B27 molecules might be also linked to factors altering antigen presentation presumably encoded in the HLA region. To determine whether TAP2 gene polymorphism may be relevant to peptide loading in humans, we typed 41 HLA-ABC, DR-identical pairs for TAP2A and TAP2B by PCR-SSO hybridization or direct genomic sequencing. In eight cases, GLO-different and, in six cases, DP-different recombinant siblings were included. Allele frequencies for TAP2A and TAP2B were as previously reported (74% and 26%, respectively). In all pairs, TAP2 gene polymorphism segregated with the DR-DQ type, mapping the TAP2 gene telomeric to the recombination hot spot in the DR-DP interval of the human class II region. We conclude that, in HLA-identical siblings, TAP2 gene differences are very unlikely to occur. Thus, in HLA-identical siblings, minor histocompatibility antigenic differences cannot be attributed to variant peptide loading due to TAP2 gene polymorphism.

Human monoclonal islet specific autoantibodies share features of islet cell and 64 kDa antibodies

The first human monoclonal islet cell antibodies of the IgG class (MICA 1-6) obtained from an individual with Type 1 (insulin-dependent) diabetes mellitus were cytoplasmic islet cell antibodies selected by the indirect immunofluorescence test on pancreas sections. Surprisingly, they all recognized the 64 kDa autoantigen glutamate decarboxylase. In this study we investigated which typical features of cytoplasmic islet cell antibodies are represented by these monoclonals. We show by double immunofluorescence testing that MICA 1-6 stain pancreatic beta cells which is in agreement with the beta-cell specific expression of glutamate decarboxylase. In contrast an islet-reactive IgM monoclonal antibody obtained from a pre-diabetic individual stained all islet cells but lacked the tissue specificity of MICA 1-6 and must therefore be considered as a polyreactive IgM-antibody. We further demonstrate that MICA 1-6 revealed typical features of epitope sensitivity to biochemical treatment of the target tissue which has been demonstrated for islet cell antibodies, and which has been used to argue for a lipid rather than a protein nature of target antigens. Our results provide direct evidence that the epitopes recognized by the MICA are destroyed by methanol/chloroform treatment but reveal a high stability to Pronase digestion compared to proinsulin epitopes. Conformational protein epitopes in glutamate decarboxylase therefore show a sensitivity to biochemical treatment of sections such as ganglioside epitopes. MICA 1-6 share typical features of islet cell and 64 kDa antibodies and reveal that glutamate decarboxylase-reactive islet cell antibodies represent a subgroup of islet cell antibodies present in islet cell antibody-positive sera.

Oligonucleotide typing reveals association of type I psoriasis with the HLA-DRB1*0701/2, -DQA1*0201, -DQB1*0303 extended haplotype

Although the pathogenesis of psoriasis is still a matter of debate, there are several lines of evidence supporting the concept of this disease being immunologically mediated with T cells playing a crucial role. Because a considerable portion of the cellular infiltrate in psoriasis consists of activated T-helper cells, expression of HLA class II antigens might be of particular importance for the understanding of its pathogenesis. Therefore, we investigated the HLA type of patients with type I (early onset, positive family history) and type II (late onset, no family history) psoriasis by means of serology (n = 89) and genotyping using sequence-specific oligonucleotide probes (n = 64). Serologic analysis of class I documented the association of type I psoriasis with HLA-Cw6, -B13, and -B57, whereas type II psoriasis showed a weaker correlation with HLA-Cw2 and -B27. Genotyping using SSO for class II detected the elevation of the HLA-DRB1*0701/2 allele frequency from 13% in normal population to 36% in type I, but only to 15% in type II psoriatics. Moreover, positive correlations with type I psoriasis were detected for HLA-DQA1*0201 and HLA-DQB1*0303. The HLA-DRB1*0701/2, -DQA1*0201, -DQB1*0303 extended haplotype was found exclusively in type I psoriasis. This is the first report documenting the association of distinct HLA class II alleles with type I psoriasis as detected on the DNA level, an approach both more specific and more sensitive when compared to serology.

Human monoclonal islet cell antibodies from a patient with insulin-dependent diabetes mellitus reveal glutamate decarboxylase as the target antigen

The autoimmune phenomena associated with destruction of the beta cell in pancreatic islets and development of type 1 (insulin-dependent) diabetes mellitus (IDDM) include circulating islet cell antibodies. We have immortalized peripheral blood lymphocytes from prediabetic individuals and patients with newly diagnosed IDDM by Epstein-Barr virus transformation. IgG-positive cells were selected by anti-human IgG-coupled magnetic beads and expanded in cell culture. Supernatants were screened for cytoplasmic islet cell antibodies using the conventional indirect immunofluorescence test on cryostat sections of human pancreas. Six islet cell-specific B-cell lines, originating from a patient with newly diagnosed IDDM, could be stabilized on a monoclonal level. All six monoclonal islet cell antibodies (MICA 1-6) were of the IgG class. None of the MICA reacted with human thyroid, adrenal gland, anterior pituitary, liver, lung, stomach, and intestine tissues but all six reacted with pancreatic islets of different mammalian species and, in addition, with neurons of rat cerebellar cortex. MICA 1-6 were shown to recognize four distinct antigenic epitopes in islets. Islet cell antibody-positive diabetic sera but not normal human sera blocked the binding of the monoclonal antibodies to their target epitopes. Immunoprecipitation of 35S-labeled human islet cell extracts revealed that a protein of identical size to the enzyme glutamate decarboxylase (EC 4.1.1.15) was a target of all MICA. Furthermore, antigen immunotrapped by the MICA from brain homogenates showed glutamate decarboxylase enzyme activity. MICA 1-6 therefore reveal glutamate decarboxylase as the predominant target antigen of cytoplasmic islet cell autoantibodies in a patient with newly diagnosed IDDM.

Selection of unrelated bone marrow donors: does the current procedure warrant complete MHC class II identity?

Bone marrow transplantation from unrelated donors is being used increasingly for the treatment of patients with leukemia and several other hematologic disorders. Selection of unrelated bone marrow donors currently relies on serological HLA identity and negative mixed lymphocyte reactions between donor/recipient pairs. As serological HLA-DP typing is not feasible, we used the HLA-DPB1 oligonucleotide typing method to investigate whether the current selection procedure can guarantee complete MHC class II identity. In 40 consecutive patients, one third (62/193) serologically HLA-A, -B, -C, -DR and -DQ identical donors were found to be MLC negative with a relative response below 5%. HLA-DPB1 oligonucleotide typing of these MLC negative donors revealed that again only one third (20/62) was also identical for DP with their presumptive recipients. In the majority of pairs a disparity in graft-versus-host direction or in host-versus-graft direction of at least one allele was seen. These data indicate that in spite of the strict MLC criteria used, the current procedure did not warrant complete MHC class II identity. This implies that oligotyping for DPB1 can improve matching and should be introduced for typing of volunteers. We speculate that DP differences may contribute to the higher incidence of graft-versus-host disease or graft rejection in unrelated transplants.

The incidence of DPB1 differences between serological and mixed lymphocyte culture matched unrelated individuals: implications for selection of bone marrow donors

Bone marrow transplantation from unrelated donors is being used increasingly for the treatment of patients with leukaemia and other disorders of lymphohaemopoiesis. Selection of histocompatible unrelated bone marrow donors currently relies on serological HLA identity and negative mixed lymphocyte cultures (MLC) between potential donor-recipient pairs. Since serological HLA-DP typing is not feasible, we used the HLA-DPB1 oligonucleotide typing method to test whether the current selection procedure can also guarantee identity for HLA-DP. In 40 consecutive patients, one-third (62/193) of the serologically HLA-A, -B, -C, -DR and -DQ identical donors were judged as MLC negative (relative response below 5%) with the presumptive recipient. HLA-DPB1 oligonucleotide typing of the MLC negative donors revealed that only one-third of these (20/62) were also identical for DP. In the majority of the pairs, we found a DPB1 disparity. A difference in the graft-versus-host direction was seen in 25/62 cases in the host-versus-graft direction in 28/62 cases and in both directions in 29/62 cases. These data indicate that, in spite of the strict MLC criteria used, the current procedure did not guarantee complete MHC class II identity. Therefore oligotyping for DPB1 can improve matching for DP and should be introduced for typing of volunteers. We suspect that DP differences may contribute to the higher incidence of graft-versus-host disease or graft rejection in unrelated donor transplants.

HLA-DPB1 oligonucleotide typing of a southwest German Caucasian population

HLA-DP genotyping with sequence-specific oligonucleotides can detected known sequence variations in the polymorphic segments of the DPB1 second exon. Since the allelic polymorphism of the 22 published alleles is based on recombination of sequence motifs from six variable regions, DPB1 typing depends on the reactivity pattern of many different probes rather than from typing with single allele-specific probes. By computer simulation, we have previously shown that the minimal set of probes to define the 22 different alleles and most of the heterozygous combinations is 18. Here we describe HLA-DPB1 typing results and allele frequencies in a panel of 200 unrelated Caucasians from Southwest Germany. The result confirmed the power of the new HLA-DPB1 typing method, but we failed to detect three of the previously described alleles in our panel. To accommodate with the observed 19 different alleles, the sequence and hybridization conditions of 17 oligonucleotide probes are given, which are able to differentiate all except two, resolved by group-specific amplification, of the 190 possible heterozygous phenotypes.

How many probes are needed for HLA-DPB1 typing with sequence-specific oligonucleotide probes? A theoretical approach using computer simulation

HLA-DP genotyping with sequence-specific oligonucleotides is used to detect known sequence variations in the polymorphic segments of the DPB1 second exon. This approach is a valuable method replacing the tedious cellular definition of DP polymorphism. We have addressed, by computer simulation, the question: what is the minimum number of probes needed to provide an unambiguous assignment of HLA-DP alleles by genotyping of heterozygous individuals? We were able to reduce the number of probes in a set defining the presently known 22 different alleles and most of the heterozygous combinations to 18 probes. Only two pairs of allelic combinations cannot be distinguished by this method, neither with our optimized set of probes nor with any larger set comprising probes of reasonable length. This is because two pairs of alleles may be the result of a reciprocal genetic exchange. These two pairs, however, could be distinguished by family analysis, direct sequencing, or DNA amplification using specific primers chosen from the polymorphic ends of the DPB1 second exon.

Mapping of an HLA-DRw52-associated determinant on DR beta 1 molecules

The molecular reaction patterns of the DRw52-specific mouse monoclonal antibodies UL-52 and 7.3.19.1 were investigated. Upon immunoprecipitation and two-dimensional IEF-SDS polyacrylamide gel electrophoresis analysis (2D-PAGE) mAb UL-52 selectively isolated DR beta 1 molecules from DRw52-positive cell lines, whereas mAb 7.3.19.1 predominantly precipitated DR beta 3 molecules. Reduced mAb UL-52 binding affinity was observed to DRw8- and DRw12-positive cells, potentially resulting from structural modifications within the antibody binding site. Comparison of mAb UL-52 reactivity with published DR beta chain amino acid sequences demonstrates that the amino acid residues -S- in positions 11 and 13 on DR beta 1 molecules essentially contribute to the formation of the antibody binding site. mAb 7.3.19.1 reactivity, on the other hand, correlates with the expression of DR beta 3 chain amino acid residues K, G and N, in positions 71, 73 and 77, respectively. In contrast to other DRw52 monoclonal antibodies described so far, mAb UL-52 demonstrates a similar reactivity to DRw52 allosera, suggesting that mAb UL-52 and DRw52 allosera possibly recognize the same or a similar determinant on DR beta 1 molecules.

Alloreactive T-cell clones raised in an HLA-B/D crossing-over family dissect HLA-DR5 and HLA-DQw3 subtypes

This study was undertaken to resolve a positive mixed lymphocyte reaction between HLA-ABC identical, HLA-D different siblings. Three CD3+ CD4+ CD8- alloreactive T-lymphocyte clones, called 2/6, 7/1, and 7/2, were generated and extensively studied. Proliferation of 2/6 cells and 7/2 cells was blocked by anti-DQ monoclonal antibodies (mAbs), whereas anti-DR and DP were not effective. Stimulation of 7/1 cells was inhibited by anti-DR, but not by anti-DQ and DP mAbs. Testing on a well-characterized panel of reference B-lymphoblastoid cell lines showed that the DQ-specific clones 2/6 and 7/2 were able to proliferate upon stimulation by cells carrying the DQw7 and DQw8 but not the DQw9 subtype of DQw3. Clone 7/1 was proliferative towards cells expressing DRw11.1 but not towards DRw11.2- or DRw12-positive cells. Moreover, this clone detected determinants present on some DRw8 cells. Correlation of the reactivity of clone 7/1 with available sequence data suggests that amino acids 67, 71, and 86 of DR beta 1 molecules played a crucial role in forming the epitope recognized by this clone. In contrast, sharing of T-cell epitopes between DQw7 and DQw8 subtypes was not inferable from specific amino acid residues. The implication of these findings for T-cell allorecognition is discussed.

Effect of cytokines on proliferation of Epstein Barr virus-transformed B lymphocytes

Plating efficiencies of EBV transformed human B cells seeded in single cell cultures are far lower (less than 1%) than observed in T cell cloning experiments. This report describes the stimulatory effect of several crude as well as recombinant growth factors on proliferation of EBV transformed B cells measured by [3H]thymidine uptake. Supernatant of LPS activated monocytes (HSF) and recombinant interleukin 4 (rIL-4), but not recombinant IL-1 beta, IL-2, IL-6, TNF alpha, GM-CSF, and interferon gamma increased [3H]thymidine incorporation. The combination of HSF and rIL-4 was found to be synergistic on B cell proliferation. Plating efficiency of EBV transformed B cells at limiting dilution was improved by HSF, but not by the combination of HSF and rIL-4.

Interleukin 2 production by alloantigen-stimulated CD4+ and CD8+ human T cell subsets: frequency of HLA class I or class II-reactive precursor cells and clonal specificity of activated T cells

A recently developed limiting dilution (LD) method was used to analyze the frequency and specificity of IL2-producing cells within alloantigen-stimulated human CD4+ and CD8+ T cell subsets. Cell sorter-separated CD4+ and CD8+ responder cells were cocultured under LD conditions with HLA class I and/or class II different Epstein Barr virus (EBV)-transformed lymphoblastoid cells line (LCL) stimulator cells in the absence of additional factors. After 3 days, IL2 in cell-free culture supernatants was measured by a colorimetric assay on IL2-dependent murine CTLL cells. Under these conditions, one out of 200-500 CD4+ and one out of 300 to 1000 C8+ T cells produced IL2 when stimulated by HLA class I and class II disparate LCL. By using selected responder and stimulator cells differing only in HLA class I (A, B, C) or class II (DR) antigens, it was found that CD4+ T cells produced IL2 in response to HLA class II antigens, while CD8+ T cells produced IL2 in response to HLA class I antigens. Surprisingly, high frequencies of IL2-secreting CD4+ T cells were noted in certain HLA-DR-identical responder-stimulator combinations. To investigate whether HLA class II antigens other than DR (i.e., DQ or DP) activate CD4+ cells to IL2 secretion, we analyzed a set of HLA-A,B,C and -DR,DQ-identical responder-stimulator cells which differed only in DP antigens. In several of these instances, we measured high frequencies (f = 1/1000 to 1/2000) of HLA-DP-reactive CD4+ IL2 producers, while the frequencies in LD cultures stimulated with autologous LCL were low (f = 1/10,000 to 1/30,000). The specificity of alloantigen-activated IL2-secreting T cells was assayed by restimulation with the original or HLA-mismatched third-party LCLs. CD4+ responder cells could be efficiently and specifically restimulated to IL2 production after a resting period of 3 to 4 days, while CD8+ cells were refractory to restimulation under these conditions. Together these data demonstrate that: 1) CD4+ and CD8+ cells are stimulated to IL2 production by HLA class II and class I antigens, respectively; 2) alloantigen-activated CD4+ IL2 producers are highly specific for stimulating HLA antigens as shown by a split culture and restimulation approach; and 3) significant numbers of CD4+ IL2-producing T cells can be activated by selected HLA-DR-identical, DP-different stimulator cells.

Monoclonal antibody to a supertypic determinant associated with HLA-DRw52

A cytotoxic mouse monoclonal antibody UL-52 (IgG2b) was obtained after immunization of a BALB/c mouse with the lymphoblastoid cell line STA homozygous for HLA-A3, B8, Cw7, DR3, DRw52, DQw2, DPw2. Fluorescence analysis on a panel of B lymphoblastoid cell lines from the 10th International Histocompatibility Workshop 1987 showed almost exact concordance of UL-52 reactivity with the presence of the HLA-DRw52 antigen. Cytotoxicity testing of UL-52 on mononuclear cells of HLA-typed individuals revealed a pattern of reactivity closely associated with the HLA-DRw52 specificity as defined by conventional alloantisera (R = 0.77). UL-52 precipitated appropriate 29,000- and 33,000-dalton bands on SDS- polyacrylamide gels under reducing conditions from an HLA-DRw52 positive B lymphoblastoid cell line. Thus, by serological and biochemical criteria UL-52 defines a supertypic determinant associated with HLA-DRw52. In contrast to most DRw52- like monoclonal antibodies, UL-52 binds to DRw8 positive cells.

Detection of an HLA-DPw1-associated epitope by an alloreactive T cell clone

An alloreactive T cell clone was generated using HLA-A, B, C, DR, DQ, D identical, but HLA-DP different homozygous typing cells as responder and stimulator. The alloproliferative and -cytotoxic clone appears to recognize an epitope associated with HLA-DPw1.

MHC class II restricted self-recognition after allostimulation: clonal analysis

After allostimulation in vitro using a combination of HLA-A, B, C, DR, DQ, D identical but HLA-DP different homozygous typing cells, 34 T cell clones were derived. Thirty-one of them were alloreactive clones, but three clones were found to be autoreactive. One of these autoreactive clones was further expanded. In order to characterize in more detail the determinant restricting the autologous response, a panel of HLA-typed peripheral blood mononuclear cells (PBMC) or Epstein-Barr virus lymphoblastoid cell lines (EVB-LCL) was typed. A good correlation of typing responses with the self haplotype HLA-A1, B8, Cw7, DR3, DRw52, DQw2 was found. Typing responses also segregated together with this haplotype in informative families. Blocking studies using MHC class I and II specific monoclonal antibodies (MoAb) linked the restricting determinant to MHC class II molecules. The clone which was both autoproliferative and autocytotoxic bore the CD3(+), CD4(+), CD8(-), Ia(+) phenotype. Antibiotics or foreign plasma proteins were ruled out as restricted determinants.

Generation and characterization of three new monoclonal antibodies detecting the allospecificities HLA-A2,w69, HLA-A3 and HLA-B13

Immunization of balb/c mice with peripheral blood mononuclear cells of a leukemic patient possessing the antigens HLA-A2,3; B7,35 resulted in the polymorphic monoclonal antibody (moab) UL-101/68 (IgM) defining HLA-A3. Immunization of a second group of balb/c mice with the lymphoblastoid cell line BER homozygous for HLA-A2; B13 revealed two polymorphic moabs UL-39/10 (IgG3) specific for HLA-B13 and UL-39/24 (IgG2b) defining HLA-A2,w69. Immunoprecipitation and polyacrylamide gel electrophoresis with the two moabs of the IgG isotype confirmed the class I structure of the recognized antigens.