Evidence for a new segregant series of B cell antigens that are encoded in the HLA-D region and that stimulate secondary allogenic proliferative and cytotoxic responses

Strong lymphoproliferative suppressive function of PLT clones specific for SB-like antigens

From a total of 37 different priming combinations between donors matched for HLA-A,B, and/or Dw/DR, but mismatched for SB, antigens, T cell clones strongly restimulated with concordance for SB specificities were isolated from only two. Most of the alloproliferative (PLT) clones obtained were restimulated by determinants not correlated with any currently known HLA product. Nonetheless, their stimulation was inhibited by a monoclonal antibody TU 39, which preferentially blocks stimulation by SB-, rather than by Dw/DR-associated determinants. Despite having an OKT4+, OKT-, Leu8- phenotype, and secreting Interleukin-2 after contact with stimulatory cells, these clones strongly suppressed proliferative responses of cloned PLT reagents as well as unprimed lymphocytes in mixed leukocyte cultures. They may thus represent a novel type of immunoregulatory T cell, stimulated by SB-related antigens, which despite their "helper/inducer" phenotype are able directly to suppress lymphoproliferative responses.

HLA class-II-specific T-lymphocyte clones with dual alloreactive functions

The relationship between T lymphocytes that proliferate in response to HLA class II antigens and those that mediate the cytotoxic response toward HLA class II target antigens was investigated. Alloreactive T-cell clones were derived under conditions in which the likelihood of clonality was high. Three populations of HLA class-II-specific T cells were identified. Two of these populations exhibited only HLA class-II-directed cytotoxicity or HLA class-II-induced proliferation. The third population of T cells exhibited both of these responses.

Possible involvement of the T4 molecule in T cell recognition of class II HLA antigens. Evidence from studies of CTL-target cell binding

The present study examines the potential role of the T4 molecule in functional cell-cell interactions between target cells and human cytotoxic T lymphocyte (CTL) clones that are specific for HLA class II alloantigens encoded by the SB locus. There were marked differences (greater than 30-fold) between the seven SB-specific clones studied with respect to their susceptibility to inhibition by anti-T4 as well as anti-T3 antibodies. We wished to test the hypothesis that such variation among the clones would be due to differences in clonal "affinity" for antigen. To quantitate differences among the CTL clones in the tightness with which they bind target cells, the clones were analyzed using a previously published assay of susceptibility of CTL-target cell conjugates to dissociation in the presence of unlabeled targets. The results revealed that the clones that were most susceptible to inhibition by anti-T4 and anti-T3 were the weakest target cell binders, and vice versa. Anti-T4 antibody could partially induce dissociation of functional CTL-target cell conjugates in the absence of any added cold targets. For the "highest affinity" clone such anti-T4 antibody-induced dissociation could be observed at 4 degrees C but not 23 degrees C. These results indicate that the T4 molecule is functionally involved in target cell binding by CTL, and raise the possibility that although it is easiest to demonstrate the function of the T4 molecule in "low affinity" clones, that function may also be operative in the "high affinity" clones.

The influence of matching for SB on MLC typing is significant but marginal

To investigate the role of SB in MLC typing responses, reactions of lymphocytes from 23 DW3-positive, HLA-D-heterozygous individuals against 9 Dw3 homozygous typing cells (HTCs) were evaluated. Significantly more clear typing reactions were observed in those combinations that were matched for SB as compared with those that were mismatched. Nevertheless, MLC responses towards HTCs that were HLA-D/DR- and SB-compatible could be very strong. An additional analysis of the influence of HLA-B and the newly defined determinants LB-Q1 and LB-Q2 demonstrated that in combinations that were matched for these markers as well, stabilized relative responses could still be over 100%.

Analysis of the structural heterogeneity and polymorphism of human Ia antigens. Four distinct subsets of molecules are coexpressed in the Ia pool of both DR1,1 homozygous and DR3,W6 heterozygous B cell lines

Four monoclonal antibodies reacting with distinct human Ia antigenic determinants have been used to demonstrate the coexpression of four distinct subsets, NG1, NG2, H40+-3/4+, and DC1 H40--3/4+, in the Ia pool of DR heterozygous or homozygous B cell lines. By two-dimensional peptide mapping the four subsets within the same Ia pool displayed structurally different beta as well as alpha subunits. The beta chain of the NG1 subset was shown to display considerable structural polymorphism when analyzed in two cell lines with distinct DR but similar DC phenotype, LG2 (DR1,1-DC1) and Raji (DR3, W6-DC1). In contrast, the beta chains of NG2, DC1 H40+-3/4+, and DC1 H40--3/4+ subsets of LG2 cells were shown to be very similar to their homologous Raji cell counterparts, thus indicating a relatively low structural polymorphism. Furthermore, the alpha chains of either one of the four subsets expressed in LG2 cells displayed very high structural similarities to the homologous counterparts in the Raji Ia pool, thus suggesting a relatively low polymorphism for the large Ia subunits described in this study. A striking feature deduced from this study was the selective subunit association of the distinct alpha-beta heterodimers.

Relation of insulin-dependent diabetes mellitus (IDD) and the HLA-linked SB system

This report deals with the question of the susceptibility for IDD association with the recently described HLA-linked SB system. The SB system is located centromeric of HLA-DR between HLA-DR and GLO. At present five specificities of the SB system, which behave as alleles, can be recognized. A total of 40 IDD patients and 96 normal controls were characterized for HLA-A, -B, -C, -DR and SB antigens. Our results confirmed the strong positive association of IDD with HLA-DR3 and -DR4 and the negative association of IDD with HLA-DR2. The genetic analysis of the SB system and IDD, however, demonstrated no significant association between alleles of SB and susceptibility for IDD. The analysis of association between alleles of HLA-DR and SB revealed no significant linkage disequilibrium in IDD patients and a significant linkage disequilibrium between SB1 and HLA-DR3 in the controls. These results suggest that the genes associated with susceptibility for IDD are primarily coded for telomeric of SB and tightly linked with HLA-DR.

Influenza A hemagglutinin-specific T cell clones strictly restricted by HLA-DR1 or HLA-DR7 molecules

The antigenic specificities, major histocompatibility complex restrictions and functional properties of influenza virus-specific proliferative cloned cell lines have been studied. These lines were specific for the H3 hemagglutinin subtype of influenza A viruses. By using a large panel of HLA-phenotyped antigen-presenting cells, it was found that the polymorphic structures, defined as DR1 and DR7 molecules, or closely associated structures, function as the restricting elements. We excluded for these lines a possible restricting role of supertypic specificities, known cross-reacting elements on DR molecules, or products of other loci in known linkage disequilibrium with the HLA-DR molecules. Such exquisitely restricted clones might be of great help in the class II typing of antigen-presenting cells. Their specific activity was stable for several months. This has allowed the study of some functional properties of these long-term-cultured cloned cell lines: interleukin 2 sensitivity and production, helper function in specific antibody synthesis and ability to stimulate in mixed leukocyte reactions.

Both alpha and beta chains of HLA-DC class II histocompatibility antigens display extensive polymorphism in their amino-terminal domains

At least three class II antigens, all composed of an alpha and a beta subunit, are encoded in the human major histocompatibility complex, i.e., DR, DC and SB. Two cDNA clones, encoding a DC alpha and a DC beta chain, respectively, were isolated from a cDNA library of the lymphoblastoid cell line Raji (DR3,w6). The two polypeptides predicted from the nucleotide sequences of these clones are each composed of a signal peptide, two extracellular domains, a hydrophobic transmembrane region and a short cytoplasmic tail. Comparison of the DC alpha sequence with two previously published partial sequences shows that the majority of the differences is located in the amino-terminal domain. The differences are not randomly distributed; a cluster of replacements is present in the central portion of the amino-terminal domain. Likewise, the allelic polymorphism of the DC beta chains occurs preferentially in the amino-terminal domain, where three minor clusters of replacements can be discerned. The non-random distribution of the variability of DC alpha and beta chains may be due to phenotypic selection against replacement substitutions in the second domains of the polypeptides.

Antigen-specific HLA-restricted human T-cell lines. I. An MT3-like restriction determinant distinct from HLA-DR

The results presented provide evidence that the HLA specificity known as MT3, BR4, or Hon7 can serve as a restriction epitope for the proliferation of certain T cells responding to mumps viral antigen. This restriction determinant was found to be HLA-linked in family studies, and to segregate centromeric to a crossover between HLA-B and DR in one family. In the population studied, the specificity was found to be associated with the DR antigens DR4, DR7, and DRw9, which are known to be associated with MT3. The ability of accessory cells to present mumps antigen in the context of this supertypic restriction determinant was blocked by a monoclonal antibody specific for MT3. Since MT3 (BR4, Hon7) has been shown to be expressed on molecules distinct from DR, our experiments suggest that such molecules are functionally important in antigen presentation to T cells.

HLA-DR7-specific monoclonal antibodies and a chimpanzee anti-DR7 serum detect different epitopes on the same molecule

We describe here two monoclonal antibodies with HLA-DR7 serologic specificity. The antibodies, SFR16-DR7M, a cytotoxic rat IgM antibody of high affinity, and SFR16-DR7G, a noncytotoxic antibody of the rat IgG 2a class, react with only DR7-positive cells in radioimmunoassay. The cytotoxic activity of SFR16-DR7M correlates completely with the presence of the DR7 specificity, and segregates with the DR7-bearing haplotype in a family. SFR16-DR7M precipitates a class II molecule with the electrophoretic characteristics of DR molecules from LG-10, an HLA-DR7 homozygous cell line. SFR16-DR7G completely inhibits the cytotoxicity of SFR16-DR7M, but only partially inhibits the cytotoxicity of a chimpanzee antiserum with DR7 specificity, Gay/Swei. In binding-inhibition studies, binding of SFR16-DR7M to LG-10 cells is only partially inhibited by the chimpanzee antiserum and vice versa. Both SFR16-DR7M and Gay/Swei reciprocally deplete the same class II molecules from a 35S-methionine-labeled detergent-solubilized membrane preparation of the LG-10 cell line. The chimpanzee serum Gay contains antibodies reactive with epitopes on separated DR7 beta chains, while both SFR16-DR7M and SFR16-DR7G bind only to DR7 alpha-beta complexes. These data suggest that at least two allogenic epitopes exist which result in the same serologic specificity, and that these epitopes differ in their requirement for alpha-beta complex formation.

Linkage disequilibrium of HLA-SB1 with the HLA-A1, B8, DR3, SCO1 and of HLA-SB4 with the HLA-A26, Bw38, Dw10, DR4, SC21 extended haplotypes

Homozygous typing cells from 13 normal HLA-A1, B8, Dw3, DR3 and five normal HLA-A26, Bw38, Dw10, DR4 individuals were typed for the following markers: HLA-SB, MB, MT; complement proteins BF, C2, C4A, C4B; and GLO. Ninety-one percent of A1, B8, Dw3, DR3 homozygous individuals (HI) tested were homozygous for BF*S, C2*C, C4A*QO, and C4B*1 (SCO1 complotype), which indicates that the SCO1 complotype is in linkage disequilibrium with the A1, B8, DR3 haplotype in randomly selected normal populations. Sixty-seven percent of HLA-A1, B8, Dw3, DR3, SCO1 positive HI also expressed SB1; since the frequency of SB1 in random Caucasian populations is 11.2%, this finding indicates that SB1 is in linkage disequilibrium with the A1, B8, DR3, SCO1 extended haplotype. All HI with the A26, Bw38, Dw10, DR4 haplotype were homozygous for both SC21 and SB4, suggesting that SC21 and SB4 should be included in the A26, Bw38, Dw10, DR4 extended haplotype. On the other hand, neither of the GLO markers were found in association with either haplotype. The results of this study indicate that HLA-SB is included in some extended haplotypes and may be important in these markers for diseases such as insulin-dependent diabetes mellitus. This study also demonstrated an apparent influence of HLA-SB on primary mixed lymphocyte culture (MLC) responses. The mean relative response of primary MLCs between individuals matched for HLA-A, B, D, DR, MB and MT but not SB was 40% of that for the MLCs with mismatched HLA-D, significantly higher than the MLCs matched for all HLA and complotypes.

Signal sequences distinguish class II histocompatibility antigen beta chains of different loci

The signal sequences of two HLA-DR beta chains and the DR alpha chain were determined. In addition, the major part of a DC beta-chain signal sequence was also elucidated. The data were obtained by combining amino acid sequence analyses of isolated alpha and beta chains with nucleotide sequencing of four cDNA clones. All signal sequences comprise 25 amino acids or more. The two HLA-DR beta-chain signal sequences are identical and exhibit only marginal homology to the DC beta-chain signal sequence. No homology is apparent between alpha- and beta-chain signal sequences. The differences in the signal sequences of the DR and DC beta chains suggest that these sequences may be used to assign beta chains to different loci of the human major histocompatibility complex.

Reactivity pattern of 15 HLA-Dw1 homozygous typing cells in primary mixed lymphocyte culture

The Dw1 specificity was highly correlated with the serologically determined HLA-DR1 antigen in the Eighth International Histocompatibility Workshop 1980. By testing a large number of HLA-Dw1, DR1 defined homozygous typing cells (HTC) in a checkerboard primary mixed lymphocyte reaction, on a panel of about 30 HLA-DR1 heterozygous individuals, and in family segregation, three Dw1 "subtypes" could be defined in association with certain HLA-A, -B, and -C-antigens. HTC TA, FRI, and FRA carrying the HLA haplotypes A11, B35, Cw4 or A3, B35, Cw4 in the homozygous state gave positive typing results with most HLA-DR1 positive panel members and stimulated only four other Dw1 HTCs (SRR less than or equal to 35%). In contrast to this operationally "broad" specificity, Dw1-HTC-HEN (HLA-A2, B44, C-, homozygous) was non-stimulatory to all HTCs except one, but gave high responses against these, leading to the definition of a "narrow" specificity included in the "broad" one. Another such "narrow" specificity was represented by HTC FEE (HLA-A2, B27, Cw2 homozygous). Typing patterns with FEE were mostly different from those defined with other HTC. In family studies a specific typing pattern for this HTC could be shown to segregate with HLA. However, within some of these responses a contribution of the HLA haplotype in the trans position must be assumed.

A matrix approach to human class II histocompatibility antigens: reactions of four monoclonal antibodies with the products of nine haplotypes

Three putative HLA-DC-specific monoclonal antibodies, Genox 3.53, BT3/4 and anti-Leu-10, and the HLA-DR-specific antibody, L243, were compared. Their interactions with molecules from homozygous cell lines expressing DR types 1 through 9 were studied. Indirect radioimmunoassays on 29 cell lines demonstrated that Genox 3.53 reactivity correlated with DR1, 2, 6; BT3/4 reactivity correlated with DR 1, 2, 4, 6, 8; and anti-Leu-10 reactivity correlated with DR1,2,4,5,6,8, and 9. In addition, one of six DR3-positive cells and three DR7, DRw10-positive cells reacted with anti-Leu-10 and one of two DR9-positive cells reacted with BT3/4. Binding studies with soluble antigen and competitive radioimmunoassays demonstrated that all three antibodies reacted with the DC1 molecule. Preincubation with BT3/4 blocked anti-Leu-10 binding; Genox 3.53 and L243 did not. Genox 3.53 and L243 were only blocked by themselves. Serial immunoprecipitation showed anti-Leu-10 reacted with non-HLA-DR molecules from cells expressing DR types 1-6, 8 and 9. However, the molecules precipitated by anti-Leu-10 were characteristic class II major histocompatibility complex (MHC) molecules. Their alpha and beta chains were of lower apparent molecular weight than the DR chains in all haplotypes. They also comigrated with the DC1 molecule precipitated by Genox 3.53. Serial immunoprecipitation also showed that anti-Leu-10 removed all Genox 3.53 reactive molecules from cell lysates, but Genox 3.53 removed only a subset of anti-Leu-10 reactive molecules. These studies show Genox 3.53, BT3/4, and anti-Leu-10 react exclusively with class II MHC molecules that are not HLA-DR, and most likely define different polymorphisms of DC molecules, the human equivalent of mouse I-A products.

Rheumatoid arthritis: relationship with HLA-D

Understanding of the genetic component of rheumatoid arthritis has been greatly enhanced by the discovery of the association of risk for development of this disease with certain histocompatibility antigens. The HLA-D region, at the centromeric end of the HLA gene complex, on the short arm of chromosome number 6, is concerned with important functions in the regulation of the immune response. The products of the HLA-D region (DR, SB, MT, and the like) function as "restriction elements" for antigen presentation, mediators of immune response and immune suppressor genes, stimulators of graft rejection, and of other allogenic effects. Rheumatoid arthritis is associated with Dw4 and DR4 in Caucasians. The association with DR4 has been observed also in Blacks and Orientals. HLA-DR4 is associated with more severe, rheumatoid factor-positive disease. Clinical and genetic heterogeneity has been revealed by studies of patients with juvenile arthritis. Conditions often associated with rheumatoid arthritis and also thought to have an immunologic basis, such as Sjögren's syndrome, Felty's syndrome, and rheumatoid vasculitis, and reactions to medications, such as gold and penicillamine, reveal an interesting spectrum of immunogenetic relationships. Thus, HLA studies have shed light on the classification of patients with rheumatoid diseases. In view of the role of HLA-D in the immune response, these studies are expected to further our understanding of the mechanism underlying predisposition for development of rheumatoid arthritis and related conditions.

Exon-intron organization and complete nucleotide sequence of a human major histocompatibility antigen DC beta gene

We have determined the complete nucleotide sequence of a human class II histocompatibility antigen DC beta gene. The gene spans more than 7 kilobases and contains five exons corresponding to the different domains of the DC beta polypeptide. The exon-intron organization is thus analogous to that of class II antigen alpha-chain genes, class I antigen heavy chain genes, and the constant parts of immunoglobulin genes, emphasizing further the evolutionary relationship among these molecules. The mature polypeptide deduced from the DC beta gene shows 93% and 88% homology, respectively, to sequences derived from two DC beta cDNA clones of other haplotypes. The allelic polymorphism of DC beta chains resides predominantly in the first extracellular domain, whereas the rest of the polypeptide is virtually constant. The exons of the DC beta gene display high homology to the corresponding exons of a murine I-A beta gene. Also, the introns show significant homology. The DC beta chains lack eight amino acids in the cytoplasmic tail, as compared to DR and I-A beta chains. This is probably due to a nonfunctional splice junction of DC beta genes, causing a separate cytoplasmic exon to be nonexpressed.

Clonal analysis of T lymphocyte response to an isolated class I disparity

A bulk primed lymphocyte reagent generated in a class II identical class I (HLA-B) disparate sibling combination demonstrated both cytotoxic [cell mediated lympholysis (CML)] and proliferative [i.e., primed LD (lymphocyte) typing (PLT)] reactivity associated with the class I antigen, Bw62. Cells from this bulk population were plated by limiting dilution and cloned by micromanipulation. Three functional groups of clones were isolated. Some clones derived were found specifically to proliferate to and lyse cells bearing the Bw62 antigen. Based on such reactivities, these clones were analogous to the class of antigen-driven, helper cell independent cytotoxic (HITc) clones previously reported from our laboratories. Other clones responded proliferatively to stimulation by Bw62 positive cells but were not cytotoxic, thus fitting characteristics of Th, although it will be necessary to test such clones for their ability to produce Interleukin 2 (IL-2). In addition, conventional cytotoxic clones which did not proliferative to, but did lyse cells bearing the Bw62 antigen were isolated. The results were consistent with the existence of both HITc and Tc mediated cytotoxicity generated against this isolated class I disparity.

Mapping SB in relation to HLA and GLO1 using cells from first-cousin marriage offspring

A newly defined leukocyte antigen system, the secondary B-cell (SB) system, was shown to be linked to HLA. The SB marker has been investigated in lymphocyte donors presumed to be genetically homozygous for HLA-A through HLA-D/DR by virtue of descent from a first-cousin marriage and of phenotypic homozygosity for these HLA markers. Of 19 donors, 3 were found to be heterozygous for SB. Studies of the families of these three donors could not distinguish with certainty whether the heterozygosity resulted from SB/DR recombination or from "pseudohomozygosity" for HLA-A through -D/DR by inheritance of two genetically unrelated but similar haplotypes. However, our data favored the occurrence of SB/DR recombination with a meiotic distance perhaps as large as 3.3 cMorgan. Recombinations were identified which mapped SB between HLA-B and GLO1. These studies demonstrate the usefulness of cells from first-cousin marriage offspring in mapping a polymorphic genetic system.

Allocytotoxic T cell clones: both Leu 2+3- and Leu 2-3+ T cells recognize class I histocompatibility antigens

T cell clones were selected which were cytotoxic for human class I major histocompatibility target antigens. Specificity was based on target cell panel studies and inhibition by monoclonal antibodies to class I determinants. Eight clones were Leu 2+3-. The cytotoxicity of these clones was inhibited by antibody to the Leu 2 antigen. Two clones expressed the Leu 2-3+ phenotype and were not inhibited by anti-Leu 2a or anti-Leu 3a antibodies. These studies indicate that class I-specific cytotoxic T cells are distributed in both T cell subsets, though predominantly in the Leu 2+3- group. In addition, these studies suggest that the Leu 3 molecule may not function in identical fashion in Leu 3+ cytotoxic T cells, which recognize class I target antigens, as in those which recognize class II targets.

HLA-DB3: population distribution and family studies of a new HLA-D antigen associated with HLA-D antigen associated with HLA-DR4 in Caucasoids

On the basis of studies with 6 HTCs in four different families the new cluster DB3 identified in the 8th Workshop can be considered an established specificity of the HLA-D series. In 112 healthy Caucasoids resident in South East England the frequency of this antigen was 2.6% similar to the frequency found in 142 Caucasoid patients with rheumatoid arthritis. The frequency in 54 unrelated Chinese individuals from Shanghai and of 120 Nigerians was 7.5% and 3%, respectively. All Caucasoid individuals who were DB3 were also DR4 whereas no such association was found in the two other population groups.

Dissection of the D-region of the human major histocompatibility complex by means of induced mutations in a lymphoblastoid cell line

This paper describes part of a mutagenic dissection of the human D-region. Twenty-six human lymphoblastoid cell mutants that had lost expressions of HLA-DR were created with a two-step procedure: (i) A mutant from which one entire haplotype had been physically deleted by gamma-rays was isolated by means of immunoselection against cells expressing a specific HLA-B antigen. (ii) This heterozygous deletion mutant was irradiated with gamma-rays or treated with ICR 191, a frameshift mutagen, and mutants that no longer expressed the remaining DR1 antigen were selected with a monoclonal antibody directed against a monomorphic DR determinant. Monoclonal antibody GENOX 3.53 was used to show that four of the gamma-ray induced DR-null mutants did not express the cis-linked MB1/MT1 locus. Since MB1/MT1 was still expressed in the other 16 gamm-ray induced and 6 ICR 191-induced DR-null mutants, the separate loss of expression of MB1/MT1 and DR1 is strong evidence that the DR1 and MB1/MT1 alloantigens are under separate genetic control in the cells we used. Since DR-null mutants bound SB2-specific monoclonal antibody ILR1, whether or not they expressed MB1/MT1, the results mean that gamma-rays resolved the genetic determinants for DR1, MB1/MT1, and SB2. Additional complexity of determinants encoded by D-region genes is indicated by the following results. The amount of MB1/MT1 antigen that was detected with ELISA tests for binding of GENOX 3.53 antibody to cells varied inversely with the number of expressed copies of DR or of a locus near DR. This could result from an increased amount of MB1/MT1 antigen or from increased binding accessibility of GENOZ 3.53-reactive antigen in DR-null mutants. Monoclonal antibodies CC 11.23 and CC 6.4 displayed patterns of binding to parental and diverse mutant cells that differed from that of GENOX 3.53, suggesting the existence of at least one additional D-region antigen that is neither SB, DR, nor MB/MT.

Expression of T-lymphoblast-encoded HLA-DR, MT, and SB antigens on human T-B lymphoblast hybrids

The Ia-like antigens of hybrids of the B-lymphoblastoid cell line (B-LCL) WI-L2 and a subline of the T-lymphoblastoid cell line (T-LCL) HSB were examined. Antigens of the HLA-DR and MT series were analyzed by indirect immunofluorescence with chimpanzee anti-DR sera and monoclonal antibodies, and antigens of the SB series were analyzed by primed lymphocyte typing (PLT). The WI-L2 X HSB hybrids expressed antigens of each series not found on either parent cell. In each case, the novel antigens were indistinguishable from those found on SB, a B-LCL established from the same individual as HSB, and are thus presumably HSB encoded.

Identification of four SB antigens by cloned cells. Population studies of Norwegians

By priming in vitro with allogeneic HLA-DR compatible and also HLA-A,B mostly compatible lymphoid cells, PLT cells resulted in recognizing a group of non D/DR allelic antigens provisionally named K, L, M and N. To improve discrimination these bulk primed typing reagents were cloned and expanded. By typing of previously SB typed lymphoblastoid B cell lines (LCL) the provisional specificities could be identified as SB1, 4, 3 and 2, respectively. Typing of 186 unrelated Norwegians gave the following gene frequences: SB1: 0.05, SB2: 0.16, SB3: 0.13, SB4: 0.42 and SB blank: 0.24. No triplets were found, the calculated gene frequencies fit with Hardy-Weinberg equilibrium, and typing of a B-DR recombinant family confirmed that the SB locus is situated centromeric to B. Associations between SB and A, B, DR antigens in the same material were generally weak, the most significant associations found were between SB1-DR3 and SB4-DR2.

Genetic mapping of a human class II antigen beta-chain cDNA clone to the SB region of the HLA complex

A class II antigen beta-chain cDNA clone was isolated from a human B-cell cDNA library by using as a probe the murine I-A beta gene. This cDNA clone, pHA beta, was shown to be distinct from the DC beta- and DR beta-related loci by DNA sequence analysis, thus suggesting that it might correspond to a third polymorphic human class II locus, SB, which encodes secondary B-cell antigens. Genetic mapping of this beta-chain cDNA clone to the SB region was performed by the blot hybridization procedure. We showed that (i) within panels of HLA-DR homozygous human B-cell lines and of unrelated individuals who have been typed for HLA antigens, differential mobility of DNA fragments segregated with distinct SB genotypes; (ii) gamma-ray-induced deletion mutants that have lost the expression of DR or DC/MT antigens but maintain SB expression preserved a pattern consistent with (a) their SB phenotype and (b) the genetic independence of the SB locus with respect to DR and DC/MT; and (iii) within an informative family, two siblings differing only for one allele at the SB locus (because of the occurrence of an internal recombination between DR and GLO) and otherwise HLA identical exhibited a restriction enzyme polymorphism linked to the SB locus. Therefore, all available data are compatible with identity between HA beta and SB beta.

The MHC in human bone marrow allotransplantation

In this chapter, we have considered the theoretical and practical background of bone marrow transplantation. The immune response and its regulation by genes within the major histocompatibility complex, particularly of the I region of the mouse and of the HLA-D/DR region in man, is of central importance in both graft acceptance (rejection) and graft-versus-host disease. Methods which are available for typing alleles at the HLA-A, -C, -B, -DR and complotype (BF, C2, C4A, C4B) loci, have been considered in detail. The extent to which recombination affects specific alleles on haplotypes within families is discussed, as is the occurrence of linkage disequilibrium and extended haplotypes in populations of unrelated individuals. Because the HLA-DR and complotype region in man is thought to be critical for the success of bone marrow transplantation, methods for typing of HLA-D by both the HTC and PLT approaches have been examined. Although HLA-D/DR assignments are easily made in normal subjects, they are ambiguous in about 50 per cent of candidates for bone marrow transplantation, including, particularly, patients with aplastic anaemia, leukaemia, and severe combined immunodeficiency. In this setting, it is particularly important to obtain additional information by modification of HLA-D typing procedures and through complotype and GLO allele determinations in all family members. Finally, we can hope that there will be an increased possibility of using non-family donors through methods for removing cytotoxic T cells from donor marrow and through the identification, in the general population, of individuals who are genotypically similar or identical to the recipient. In this regard, the recognition that some 30 per cent of chromosome 6 in caucasians (50 per cent of individuals) bear extended haplotypes, which include a relatively fixed set of alleles particularly in the HLA-B, -DR, complotype and GLO regions, offers considerable promise.

LB-Q1 and LB-Q2: two determinants defined in the primed lymphocyte test and independent of HLA-D/DR, MB/LB-E, or SB

The primed lymphocyte test (PLT) was used to prepare reagents between HLA-D/DR identical individuals. Two sets of primed lymphocytes were obtained which recognized the new determinants referred to as LB-Q1 and LB-Q2, respectively. LB-Q2 is significantly associated with HLA-A1, -B8, and -D/DR3. Nevertheless, LB-Q1 and LB-Q2 seem to be distinct from any of the established HLA antigens. No association with any of the alleles of the SB system was observed. A recombination between HLA-D/DR and HLA-B suggested that the locus encoding LB-Q2 is situated on the telomeric side of HLA-D/DR.

Human allospecific T cell proliferative clones: different T cell clones expressing an apparently identical HLA class II specificity are heterogeneous in regard to their proliferative inhibition by a panel of monoclonal antibodies against human Ia-like antigens

Four independent PLT clones displaying an apparently identical class II specificity (i.e., Dw/DR3) were found to give a heterogeneous pattern of inhibition in relation to 15 anti-class II mAb and an anti-beta 2m mAb used as a control. Some clones were inhibited by all anti-class II mAbs, irrespective of the cluster of molecular subsets with which they reacted. Such clones were also inhibited by the control anti-beta 2m mAb. Other clones were inhibited by only a few of the mAb tested. Within this group of T clones following the addition of a limiting amount of conditioned medium the inhibitory data of all independent clones with an identical specificity were inhibited by the same mAb; under these conditions, it was possible to relate the mAb inhibition patterns with the specificity of the T cell clones and these T cell specificities with the epitopic cluster/molecular subsets defined by these mAbs. A new level of T cell subset heterogeneity within T cell clones with apparent identical proliferative specificities is demonstrated, in relation to the T cell clone "susceptibility" or "resistance" to the effects of anti-class II mAbs directed towards their own Ia-like antigens.

Five epitopes of a differentiation antigen on human inducer T cells distinguished by monoclonal antibodies

A series of mouse monoclonal antibodies reacting with human T cells of the helper/inducer subclass, OKT4, 4A, 4B, 4C, and 4D, have been reported. Using double-fluorescent staining and complement-mediated depletion, it was shown that the antigen(s) recognized by OKT4, 4A, 4B, 4C, and 4D antibodies are present on the same cell. Using FITC-labeled OKT4, 4A, 4B, 4C and 4D, a lack of competition between the antibodies for their epitopes was shown. Immunoprecipitation of the antigen recognized by each antibody yielded a molecule of approximately 60,000-62,000 Da. Sequential precipitation with several antibodies resulted in a minimum of additional precipitated antigen following removal of the first antigen. Capping of cell surface antigen with OKT4, followed by staining with OKT4, 4A, 4B, 4C, or 4D, indicated that the epitopes for all five antibodies co-cap. A sandwich ELISA assay using OKT4 and the other antibodies showed that molecules binding to OKT4A, 4B, 4C, and 4D also bound OKT4. It can therefore be concluded that monoclonal antibodies OKT4, 4A, 4B, 4C, and 4D recognize distinct epitopes present on a molecule of approximately 60-62,000 Da on human helper/inducer T cells.

A minimum of four human class II alpha-chain genes are encoded in the HLA region of chromosome 6

The major histocompatibility complex (MHC) in man, also called the HLA region, is located on the short arm of chromosome 6 and encodes antigens involved in immunological processes. The class II HLA antigens consist of two noncovalently associated polypeptide chains, one of molecular weight 34,000 (alpha) and the other of molecular weight 29,000 (beta). The extensive polymorphism of the beta chain(s) has allowed the genetic mapping of the corresponding beta gene(s) to the HLA-DR region. cDNA clones for the HLA-DR alpha chain have been used to map the non-polymorphic DR alpha-chain gene to chromosome 6 using mouse-human somatic cell hybrids. Similarly, the DR alpha-chain gene has been mapped to the short arm of chromosome 6 centromeric to the HLA-A, -B and -C loci by in situ hybridization experiments. We isolated a cDNA clone that is related to the DR alpha chain and encodes the class II antigen DC alpha chain. We describe here how this DC alpha clone was used to find two or three additional alpha-chain genes by cross-hybridization and how HLA-antigen loss mutants of a human lymphoblastoid cell line (LCL) were used to ascertain that these additional class II antigen alpha-chain genes are also located in the HLA region.

Stimulation in primary MLR caused by a PLT defined non-HLA-D/DR determinant, EP1

The influence in primary mixed lymphocyte culture reaction (MLR) of a primed lymphocyte typing (PLT) defined non-HLA-D/DR determinant, EP1, was investigated. In primary MLR between HLA-D/DR compatible lymphocytes, the response of the lymphocytes from 14 EP1-negative HLA-D/DR heterozygous individuals towards two EP1-positive homozygous typing cells (HTCs) was on an average approximately 35% higher than the response towards two EP1-negative HTCs (P less than 0.01). The strength of the MLR between lymphocytes from 25 EP1-negative and 10 EP1-positive individuals matched for two HLA-D/DR antigens was investigated. The average responses of EP1-negative lymphocytes against EP1-positive lymphocytes were approximately 40% higher than the average responses against EP1-negative lymphocytes (P less than 0.01). These data indicate that the PLT defined determinant EP1 causes stimulation in primary MLR.

Expression of HLA-DR antigens at the surface of mouse L cells co-transfected with cloned human genes

The H-2 I region in the mouse and the HLA-D region in humans contain a set of polymorphic genes which encode Ia antigens and control the immune response. Cloned genes for the different polypeptide chains of one of the human Ia antigens, HLA-DR, have been used for the co-transformation of mouse L cells. Expression of HLA-DR antigens at the surface of transfected mouse cells has been documented with monoclonal antibodies.

Human 'Ia' antigen populations defined by monoclonal antibodies

The relationships between the antigens recognized by four monoclonal anti-human 'Ia'-like antibodies were investigated using sequential immunoprecipitation and capping techniques. Two of the antibodies were 'monomorphic' and have previously been shown to recognize epitopes in which carbohydrate residues are involved, whereas the two 'polymorphic' antibodies recognized protein-defined epitopes--one of these epitopes being present on MB+DR- molecules. In the absence of an indisputable anti-DR monoclonal antibody, it was not possible to conclusively verify which 'Ia'-encoded antigens were detected by the anti-'Ia'-like monoclonal antibodies. Nevertheless, several firm conclusions could be drawn: (a) so-called 'monomorphic' antibodies do not necessarily react with all 'Ia' molecules encoded by a single locus--from the results using the two monomorphic antibodies, B5.1 and 3F1.1, described herein, two populations of antigens being B5.1+3F1.1+ and B5.1+3F1.1- were identified; (b) cross-reactivity of a polymorphic determinant expressed on antigenically-separable 'Ia' molecules was noted--using the two polymorphic antibodies, 26.1 and F5C9, molecules which were 26.1+F5C9+ and 26.1-F5C9+ were identified; and (c) the data clearly point to the existence of at least two loci coding for 'Ia'-like antigens (one of which may or may not be the HLA-DR locus). Given that polymorphisms can now include protein- and carbohydrate-defined epitopes, that cross-reactions occur and that the definition of DR itself by monoclonal antibodies is not clear, the complexity of the human 'Ia' antigens is apparent.

In vitro generation of cytotoxic cells specific for human minor histocompatibility antigens by lymphocytes from a normal donor potentially primed during pregnancy

A normal female donor (H9) is described, whose cells generate strong cytotoxicity against a human minor histocompatibility antigen in vitro. These cytotoxic T lymphocytes are generated after secondary restimulation with cells from an HLA-A, -B, -C, and -DR-matched donor and are HLA restricted (HLA-B7). No other donor could be identified whose cells responded to this antigen. The two children of donor H9 are virtually HLA identical to her and one of the children expresses the relevant minor histocompatibility antigen. These data suggest that priming in vivo during pregnancy has facilitated cytotoxic T cell response to human minor histocompatibility antigens in vitro.

Primary and secondary MLR characterization of three allelic variants of HLA-Dw7 segregating in a single family

Three of four parental haplotypes of a kindred from the Old Order Amish religious isolate carried HLA-DR7 and specificities of the HLA-Dw7 "cluster." Intrafamily primary and secondary mixed lymphocyte responses clearly distinguished the three Dw7-related allelic specificities. Two of the specificities fall within the Dw11 crossreacting group, designated here as Dw11 "short" (Dw11S) and Dw11 "long" (Dw11L), while the third is more closely related to Dw7. Reaction patterns in this family illustrate the complexity of antigen recognition in primary and secondary mixed lymphocyte responses and the important role played by the responder cell in generating discriminatory primed lymphocyte typing reagents.

Human influenza virus-specific T helper cell clones can be restricted by MHC products different from serologically defined HLA-DR antigens

Clones of human influenza A virus-specific T lymphocytes were generated by limiting dilution after several in vitro stimulations with autologous influenza A/USSR virus-infected cells. The clones were expanded in T cell growth factor and then grown only in the presence of antigen and irradiated stimulator cells. The clones showed antigen specificity in that they were stimulated only by cells infected with influenza A virus, but not with influenza B virus; some clones even showed distinct reactivity patterns with several influenza A virus subtypes. All clones had the OKT3+4+8-phenotype. Analysis of the restriction elements for the recognition of viral antigens, demonstrated that most clones recognized antigens associated with but not identical to serologically defined HLA-DR specificities. From the recognition pattern with HLA-DR typed donors, three different restricting antigens could be demonstrated.

Enhanced expression of human Ia antigens by chronic lymphocytic leukemia cells following treatment with 12-O-tetradecanoylphorbol-13-acetate

Using a panel of monoclonal antibodies which detect framework determinants of human-Ia alpha and beta polypeptides and the DC-specific monoclonal antibody Genox 353, the in vitro effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the expression of Ia antigens by cells from chronic lymphocytic leukemia (CLL) patients have been studied. In all subjects studied a great increase in expression of framework Ia determinants was found following culture of CLL cells for 90 h with TPA at 10(-7) g/ml. TPA treatment of CLL cells also induced increased expression of Genox 353+ antigens, in some cases where Genox 353 binding was either negligible or not detectable in cells cultured in the absence of TPA.

HLA-D and -DR antigens on human amniotic fluid cells. I. Lack of expression of HLA-D

Human amniotic fluid cells, known to express HLA-A, -B, and -C antigens, were tested for the presence of lymphocyte-stimulating antigens (LD or HLA-D) using modifications of the mixed lymphocyte culture (MLC) and primed lymphocyte typing (PLT) tests. Peripheral blood lymphocytes were co-cultured with various concentrations of allogeneic amniotic fluid cells, either growing as a monolayer culture in microtiter plates or suspended in medium following treatment with trypsin. The kinetics of such mixed lymphocyte amniotic fluid cell culture (MLAC) reactions were followed during days 3 to 8. Under none of these conditions did amniotic fluid cells significantly stimulate allogeneic lymphocytes, even after lymphocytes were specifically primed in the PLT assay to the HLA-D antigens segregating in the family of the amniotic fluid cell donor. Furthermore, in three-cell experiments, amniotic fluid cells failed to inhibit an ongoing MLC reaction, indicating that the absence of proliferative response to amniotic fluid cells is not due to active suppression. Taken together, these data strongly suggest that amniotic fluid cells either do not express HLA-D antigens or do not express them in a form that is detectable in either primary or secondary MLC.

Detection of non-HLA-DR determinants by alloreactive lymphocyte clones

Using the soft-agar colony assay, we have generated three MT3-associated clones: HJ1, HJ13, and HJ39, from an MLR combination of two unrelated individuals. Another clone, HJ37, appeared to recognize a novel HLA-D determinant. PLT inhibition studies with monoclonal anti-Ia-like antibodies (Mab) were conducted on clones HJ1, HJ39, and HJ37. Five different anti-DR Mab had no significant inhibitory effect on these clones. On the other hand, two Mab SG171 and Q5/13 which appear to react with DR and MT3 (I-A like) molecules strongly inhibited the two MT3-specific PLT clones. While SG171 and Q5/13 had little effect on HJ37, it was observed that a polymorphic Mab 17.15 had a strong inhibitory effect. These results, in concordance with biochemical data on Ia molecules precipitated by these Mab, suggest that these alloreactive clones may recognize non-DR PLT determinants. They also provide further indirect support that MT3 molecules represent the human homologue of murine I-A molecules.

Distinct HLA-DR epitopes and distinct families of HLA-Dr molecules defined by 15 monoclonal antibodies (mAb) either anti-DR or allo-anti-Iak cross-reacting with human DR molecule. I. Cross-inhibition studies of mAb cell surface fixation and differential binding of mAb to detergent-solubilized HLA molecules immobilized to a solid phase by a first mAb

A series of HLA-DR-reactive mouse anti-human B cell or anti-Ia monoclonal antibodies (mAb) have been used to explore the serological complexity of human class II antigens at the determinant level, using two techniques: (a) cross antibody-binding competitor assays using 125I-labeled and-unlabeled mAb were performed to study the topological organization of the corresponding determinants to determine epitopic clusters recognized by this collection of mAb and (b) differential reactivity of mAb to detergent-solobilized solid-phase-immobilized HLA-DR molecules to determine epitopes expressed on identical DR isotypes. The fifteen mAb could be classified according to the first technique as falling into three different epitopic clusters. Using the second technique, we were able to define at least two independent molecular subsets, one co-expressing two of the three epitopic clusters and the second expressing only the third one. We could not formally identify molecular subsets expressing only one of the first two clusters, using the second technique. The precise serological mapping of the determinants recognized by various anti-class II mAb should prove very useful if such mAb were to be introduced in anti-class II-specific T cell clone blocking experiments. We anticipate that some of them should facilitate the correlation at the clonal level between the T cell repertoire and the epitopes or molecular subsets defined by these mAb. However, within mAb belonging apparently to a same cluster, some could mediate different biological effects.

Age-related loss of function of alloactivated interleukin 2-propagated human primed lymphocyte typing clones

Human lymphocytes alloactivated in vitro were cloned by limiting dilution in the presence of filler cells and interleukin 2 (IL 2)-containing supernatants of phytohaemagglutinin-stimulated lymphocytes. Clones with allospecific proliferative reactivity (PLT clones), measured by tritiated thymidine (3H-TdR) incorporation, were selected for extensive IL 2-dependent expansion. The cloned lines had finite lifespans, ranging from an estimated minimum of 28 to greater than 65 doublings. Function as PLT reagents, however, was retained in all cases for only an estimated 30 cell doublings. This apparent cessation of function was not caused by loss of the ability to metabolize thymidine, since lines continuing to grow for greater than 30 doublings still incorporated 3H-TdR in the presence of IL 2. An altered requirement for stimulating antigen (number of stimulating cells), or altered response kinetics, did not contribute to loss of PLT function. Exogenous IL 2 added during restimulation to responders previously 'rested' overnight without IL 2 did not restore the response. Thus, under present experimental conditions, functional lifespans of cloned PLT reagents appear fixed at approximately 30 cell doublings.