A novel HLA-D/DR-like antigen specific for human B lymphoid cells. Biochemical evidence for similarity to but nonidentity with known HLA-D/DR antigens

Dissecting the transcriptional program of phosphomannomutase 2 deficient cells: B-LCL as a valuable model for congenital disorders of glycosylation studies

Congenital disorders of glycosylation (CDG) include 150 disorders constituting in genetically and clinically heterogeneous diseases, showing significant glycoprotein hypoglycosylation that leads to pathological consequences on multiple organs and systems which underlying mechanisms are not yet understood. A few cellular and animal models have been used to study specific CDG characteristics although they have given limited information due to the few CDG mutations tested and the still missing comprehensive molecular and cellular basic research. Here we provide specific gene expression profiles, based on RNA microarray analysis, together with some biochemical and cellular characteristics of a total of 9 control EBV-transformed lymphoblastoid B cell lines (B-LCL) and 13 CDG B-LCL from patients carrying severe mutations in the PMM2 gene, strong serum protein hypoglycosylation and neurological symptoms. Significantly dysregulated genes in PMM2-CDG cells included those regulating stress responses, transcription factors, glycosylation, motility, cell junction and, importantly, those related to development and neuronal differentiation and synapse such as CA2 and ADAM23. PMM2-CDG associated biological consequences involved the unfolded protein response, RNA metabolism and the endoplasmic reticulum, Golgi apparatus and mitochondria components. Changes in transcriptional and CA2 protein levels are consistent with CDG physiopathology. These results demonstrate the global transcriptional impact in phosphomannomutase 2 deficient cells, reveal CA2 as a potential cellular biomarker and confirm B-LCL as an advantageous model for CDG studies.

Class II transactivator (CIITA) isoform expression and activity in melanoma

In contrast with melanocytes, melanomas display constitutive expression of HLA-DR (HLA-DR+). This abnormal expression has been associated with tumour progression and metastatic dissemination. We have previously reported that this deregulation of HLA-D genes is due to the abnormal constitutive expression of the lymphocyte-specific isoform of class II transactivator (B-CIITA), in addition to its fibroblast form (F-CIITA), which is usually expressed in major histocompatibility complex (MHC) class II-negative interferon-gamma-induced cell types, such as melanocytes. In this study, we investigated the abnormal expression of B-CIITA in a panel of melanoma cell lines displaying differential HLA-DR expression profiles, and analysed whether such a molecular event can participate in tumour progression. Our results showed that the abnormal expression of B-CIITA did not have any particular effect, in comparison with F-CIITA, on the classical activity of CIITA HLA-D gene regulation. As CIITA has also been shown to regulate genes other than HLA-D, we evaluated the modulation of those encoding cyclin D1, YARS (tyrosyl-tRNA synthetase) and TRIP1 (transforming growth factor (TGF)-beta receptor-interacting protein), proteins involved in cell cycle/apoptosis balance, angiogenesis and resistance to TGF-beta, respectively. In contrast with other cell types, neither B-CIITA nor F-CIITA was able to modulate these genes in melanoma cell lines. Thus, the activity of CIITA, whether lymphocyte-specific or fibroblast-specific, is restricted to HLA-D gene expression in these tumours. Accordingly, our data suggest that CIITA is not involved per se in tumour progression; rather, it is the MHC class II molecules themselves, through tumour antigen presentation and the induction of tumour antigen-specific CD4 lymphocyte anergy, that may participate in immune escape and melanoma progression.

HLA class-II antigen-mediated induction of a proliferative response to anti-IgM in human B lymphocytes

Signal transduction via HLA class-II antigens has been studied using human resting B lymphocytes and monoclonal anti-HLA class-II antibodies. An increased intracellular calcium flux, phosphatidylinositol biphosphate hydrolysis and activation of protein kinase C have all been observed following signal transduction via HLA-class-II molecules. The interaction of HLA-class-II-mediated signalling with sIg-mediated signalling has been studied using a non-mitogenic anti-sIg. This combination provides a model for T-cell-dependent antigenic stimulation. The results demonstrate that stimulation via HLA class-II antigens permits a proliferative response to an otherwise non-mitogenic anti-sIg and that this effect is not restricted to one HLA class-II isotype. These data suggest that HLA-class-II-mediated signalling is important in responses to T-cell-dependent antigens.

Intracellular events associated with inhibition of B cell activation by monoclonal antibodies to HLA class II antigens

We have investigated several aspects of the inhibitory effects of monoclonal antibodies (mAb) directed against MHC class II antigens in B cell activation/proliferation, using a panel of mAb specifically reactive with antigens encoded by HLA class II loci (DP, DQ, DR). All mAb except the anti-DP mAb inhibited significantly anti-mu plus B cell growth factor-induced DNA synthesis. Only one mAb, however, which was reactive with gene products of all three class II loci (DP, DQ, DR) inhibited anti-mu-induced DNA synthesis as well as c-myc mRNA expression. In addition, the same mAb inhibited the early events induced by anti-mu stimulation alone, including phosphatidylinositol turnover and elevation of [Ca2+]i. In contrast to previous findings in the murine system, none of the anti-MHC class II mAb used in this study increased the cAMP levels.

Downregulation of c-myc RNA is not a prerequisite for reduced cell proliferation, but is associated with G1 arrest in B-lymphoid cell lines

We related the effects of c-myc expression on the ability of growth inhibitors to block the cells in the G0/G1 phase of the cell cycle. In two different B-cell lines, there was an association between the accumulation of cells in the middle to late G1 phase of the cell cycle and a rapid transient downregulation of c-myc mRNA levels. The phorbol ester TPA and the adenylate cyclase activator forskolin reduced the c-myc RNA, levels and after 3 days of treatment a proportion of the cells accumulated in G1. In contrast, neither interferon-gamma, tumor necrosis factor-alpha nor the monoclonal antibody 33-1 against DQ major histocompatibility antigens changed the cell-cycle distribution or regulated the c-myc RNA levels. Yet, all five growth inhibitors reduced the proliferation to approximately the same extent. The growth reduction was not accompanied by definite differentiation, as judged by the absence of the B-cell differentiation marker B1 (CD20).

Molecular complexity of HLA-DQw3: the TA10 determinant is located on a subset of DQw3 beta chains

In attempts to examine the relationships between serologic and structural polymorphisms of HLA-DQ molecules we have analyzed several monoclonal antibodies generated against polymorphic determinants on HLA-DQ molecules. One antibody, SFR20-DQw3, has a serologic reactivity like that of the previously characterized anti-DQw3-like monoclonal antibody, IVD12, but differs from IVD12 in its affinity for DQw3 molecules associated with DR4 and DRw9 haplotypes. Two other monoclonal antibodies have identical serologic and molecular specificity, and react with a subset of DQw3 positive cells; they have been designated SFR20-DQ beta 5. Biochemical analysis of the DQ molecules carried by DQw3-positive cell lines associated with different DR haplotypes (DR4, DR5, DRw8, DRw9, DRw12), reveal the presence of at least three different kinds of beta chains carrying the DQw3 epitope. All the cell lines bound by SFR20-DQ beta 5 (DR5, DRw8, and DRw12) possess DQ beta chains of indistinguishable electrophoretic mobility, which are different from the DQ beta chains of DQw3 cell lines not bound by this antibody while DQw3 beta chains carried by DR4 and DRw9 haplotypes are distinct from DQ beta 5-positive BLCL and from each other. The serologic reactivity of antibody DQ beta 5 correlates perfectly with an RFLP of the DQ beta gene designated DQw3.1 (Kim et al.: PNAS 828139, 1985), and with the serologic specificity TA10 as defined during the Ninth International Workshop (Schreuder GMT et al.: Histocompatibility Testing 1984). SFR20-DQ beta 5 reacts with a separated beta chain by Western blot analysis. The finding of indistinguishable beta chain electrophoretic mobility for all DQ beta 5/TA10 positive cell lines tested provide the molecular basis for these specificities, and strongly suggest that antibody SFR26-DQ beta 5 detects a single allele of the multiple DQ beta alleles which can contribute to the formation of the DQw3 specificity.

An antiviral T-cell clone defines a functional supertypic specificity shared by different HLA-DR molecules from DR2-short, DRw11, and DRw13 haplotypes

An influenza virus-specific HLA class II-restricted human T4+ clone (Ij) allows us to define a new functional supertypic HLA class II specificity shared by three different haplotypes. Influenza A virus-infected antigen-presenting cells of these three haplotypes, HLA-DR2 short, DRw11, and DRw13, are able to stimulate Ij cells. The same precise viral specificity is seen in all three cases. Proliferation inhibition experiments using HLA-specific monoclonal antibodies demonstrate that HLA-DR products are involved in all cases. However, according to the DR specificity of the antigen-presenting cell, differential blockings by a series of DR-specific monoclonal antibodies suggest that the functional epitope is shared by different HLA-DR molecules. This is confirmed by two-dimensional gel analysis of the HLA-DR beta chains expressed in the three haplotypes.

Isolation and allelic polymorphism of cDNA clones and genomic clones of HLA-DP heavy and light chains

From a human cDNA library constructed from consanguineous HLA-homozygous cell line AKIBA (HLA-A24, Bw52, DR2, Dw12, Cp63 Cp63: a new DP type), cDNA clones encoding the heavy and light chains of an HLA-DP Cp63 alloantigen were isolated and analyzed by restriction enzyme mapping and nucleotide sequence determination. Allelic comparisons of DP alpha and DP beta cDNA sequences showed that the amino acid sequence of the DP alpha chain was less polymorphic than that of the DP beta chain. In the DP beta chain, the polymorphic region was restricted to the beta 1 domain. We also isolated and characterized 15 genomic phage clones spanning a 74 kilobase (kb) pair of the DP region which were found to contain one DP alpha gene, one DP-like alpha gene, one DP beta gene, and one DP-like beta gene. Genomic blot analyses with different HLA-DP type cell lines using DP alpha cDNA as a probe revealed EcoRI fragment length polymorphism around the DP alpha gene.

Follicular mantle zone cell subpopulations detected by monoclonal antibody SN3

A monoclonal antibody, SN3, has been prepared against a cell membrane fraction of the pre-B leukemic cell line NALM-1. By radioimmunoassay, SN3 reacted with four of four non-T/non-B, two of two pre-B and one of three leukemic B cell lines. The reagent was unreactive, however, with established leukemic T and myelomonocytic cell lines or normal B cell lines. On immunohistochemical assays on frozen sections of nine reactive lymph nodes and three spleens, SN3 showed a preferential binding to 50-95 per cent mantle zone (MZ) cells and 5-20 per cent interfollicular or red pulp B-lymphocytes. This was uninhibited by pre-incubation with heterologous anti-HLA-DR or anti-delta reagents. SN3 was unreactive with normal germinal centre (GC), epidermal or Langerhans cells but did react with less than 1 per cent thymic B-lymphocytes. In eight follicular small cleaved cell lymphomas tested SN3 exhibited three patterns of reactivity: peripheral follicular, combined peripheral and central follicular, and combined follicular and interfollicular. Three follicular lymphomas were essentially SN3-. In three diffuse small lymphocytic lymphomas, SN3 showed patchy areas of reactivity unassociated with proliferation centres. In four diffuse B-cell lymphomas (one mixed small and large cell, two large non-cleaved cell, and one small non-cleaved (Burkitt) cell), SN3 reactivity was uniformly distributed in the majority (60-90 per cent) of the cells. SN3 was unreactive with one diffuse B-large cell lymphoma, three nodal T-cell lymphomas and three cases of mycosis fungoides. The findings indicate that SN3 detects an antigen that is present in subpopulations of normal MZ cells, the antigen is also detected in GC cells undergoing lymphomatous transformation but is not readily detected in normal GC cells, and the antigen is also expressed in subpopulations of diffuse B- but not T-cell lymphomas.

Multiple epitopes on a single DQ molecule from the DQw3-carrying haplotypes

Multiple polymorphisms on the DQ molecule(s) have been detected by monoclonal antibodies (MoAbs). Among these, TA10 and IIB3 have been described as two new alleles in the DQ region other than the conventional DQw1-w3 allelism. The TA10 specificity is DQw3-related and is in linkage disequilibrium with DR5 and weakly associated with DR4. The IIB3 specificity is DQw1-related and is in linkage disequilibrium with DR2, DR4, DRw9 and DRw13. Thus, the DQw3-carrying haplotypes are either positive with TA10 or IIB3. The molecular and topological analysis has revealed that both TA10 and IIB3 determinants were expressed on a single DQ molecule that also carried the DQw3 determinants on DR5 and DR4 cell lines, respectively. Thus, a single DQ molecule generated multiple epitopes detected by alloantisera and/or MoAbs at least on the DQw3-carrying haplotypes. These would be useful for unraveling the largely unknown functions of the DQ class II molecules.

Functional definition of HLA-DR and -DQ epitopes specific for DR2-short, DwFJO haplotype

T-lymphocyte clones specific for the influenza A/Texas virus were obtained by limiting dilution of activated T cells from an HLA A2/3,B7/39,Cw -/-,DR2-short/2 short,DQw1,DwFJO/FJO donor. Among the proliferating clones studied, and irrespective of their antigenic specificities, most of them were restricted by epitope(s) on HLA-DR molecules present only on DR2-short/DwFJO cells but not on DR2-negative or DR2-long positive (Dw2,Dw12,Dw-) cells. Two clones were restricted by epitopes borne by DQ products. Here again, these epitopes were present on DR2-short/DwFJO but not on DR2-long,DQw1 (Dw2,Dw12) cells, indicating that the DQw1 molecules of DR2-long and DR2-short haplotypes are different. Taken together, these results indicate that the DR2-short,DwFJO haplotype is characterized by both HLA-DR- and DQ-specific molecules. Finally, one clone was restricted by an epitope shared by DR products from DR2 short/DwFJO, DRw11, and DRw13 haplotypes. This latter functional determinant has never been described until now.

A new polymorphic determinant on HLA-DQ molecules

In man, the immune response genes are located within the HLA-D/DR region, and the gene products, the Ia antigens, are expressed on B lymphocytes, monocytes, and a percentage of null cells and activated T lymphocytes. We recently identified a human Ia antigen, K19, which appeared to be limited in its expression to B lymphocytes, and to be preferentially expressed on the more mature cells within this population. This work was facilitated by a monoclonal antibody. HK-19, which recognized a monomorphic determinant of this Ia molecule. We now report the characterization of a second monoclonal antibody, HK-13, which recognized the same molecule as HK-19, but only on cells from some individuals. The greater affinity of HK-13 allowed more complete characterization of the K19/K13 molecule. This characterization included cytofluorography, two-dimensional gel electrophoresis, tryptic peptide mapping, and partial N-terminal amino acid sequencing, and indicated that K19 and K13 were epitopes on HLA-DQ (DC) molecules. The pattern of reactivity of HK-13 on a panel of typing cells did not correlate with any of the known HLA-DQ polymorphic determinants. Thus, HK-13 is a new polymorphic determinant of the HLA-DQ series.

Cells homozygous for two HLA-DR7-associated HLA-D specificities express highly similar DR molecules but different DQ molecules

The Ia molecules expressed by cells homozygous for two distinct HLA-DR7-associated HLA-D specificities, Dw7S and Dw11L, were compared. The complete Ia phenotypes of these cells are DR7, DRw53, DQw2, Dw7S, DPw4 and DR7, DRw53, DQw3, Dw11L, DPw4, respectively. Immunofluorescence analysis revealed that three DQ-specific monoclonal antibodies (Leu-10, 33.1, and HK-19), which detect polymorphic DQ determinants that do not correspond to known serologic specificities, are nonreactive with DR7, Dw7S cells but are reactive with DR7, Dw11L cells. The DR molecules isolated from Dw7S and Dw11L cells are very similar and comigrate when analyzed together by two-dimensional gel electrophoresis. In contrast, the DQ molecules isolated from these cells are structurally distinct: the DQ beta chains of DQw2-bearing molecules from Dw7S cells are very basic, while those of DQw3-bearing DQ molecules from Dw11L cells are more acidic. The finding that two DR7, D-different cells express indistinguishable DR molecules and structurally distinct DQ molecules documents a unique pattern of Ia molecular organization which is different from those previously described for the DR2-, DR4-, or DRw8-associated HLA-D specificities.

RCH-ACV: a lymphoblastic leukemia cell line with chromosome translocation 1;19 and trisomy 8

A cell line (RCH-ACV) was established from a bone marrow sample of a child with acute lymphoblastic leukemia (ALL). The cell line lacked Epstein-Barr virus nuclear antigen and exhibited a recently described nonrandom chromosome translocation, 1;19, thought to be associated with pre-B-ALL and poor prognosis. Banding studies confirm that the breakpoint of chromosome #19 occurs at p13.3. Cell surface marker analysis using a panel of monoclonal antibodies revealed markers consistent with common ALL phenotype. Although the cells did not show cytoplasmic immunoglobulin, studies of the immunoglobulin gene rearrangement confirmed the pre-B phenotype. This cell line could be of great value to studies of the role of the specific translocation 1;19 in the etiology of pre-B-ALL.

The specific induction of myc protooncogene expression in normal human B cells is not a sufficient event for acquisition of competence to proliferate

Resting human B cells can be activated to proliferate in the presence of both polyclonal antibodies to immunoglobulin mu heavy chains and B-cell growth factor (BCGF). This process appears to be temporally controlled in that the initial activation of the B cells and their responsiveness to BCGF is carried out by polyclonal anti-mu-chain antibodies alone. We have used this system to investigate the role of the c-myc gene in the cell cycle of normal human peripheral blood B cells. Our results show that the polyclonal anti-mu-chain antibody-induced B-cell activation is accompanied by a specific induction of c-myc gene expression without promoting subsequent entry into the S phase unless BCGF is added. Monoclonal antibodies to either mu chain or the pan-B-cell antigen Bp35 also revealed a similar G0-to-G1 transition and activation of c-myc gene expression. However, unlike activation with polyclonal anti-mu-chain antibodies, cells stimulated with these monoclonal antibodies do not acquire responsiveness to BCGF. The results imply that additional inducible functions must be present to potentiate the myc-specific function in order for the B cells to acquire the capacity to proliferate in response to BCGF. These findings are discussed in relation to the origin of B-cell malignancies.

Genetic complexity and expression of human class II histocompatibility antigens

The genes encoding nearly all of the serologically defined class II antigens of the major histocompatibility complex have been isolated. Three class II loci have been studied in great detail. The DR region contains a single alpha gene and 3 beta chain genes, 1 of which is a pseudogene. The DR alpha chain gene has been linked to a DR beta gene which encodes a beta protein which contains the serological determinant MT3. A second cosmid cluster contains 2 beta genes, 1 of which encodes the DR4 allospecificity. The identification of these genes has been made by the comparison of amino terminal sequences of DR molecules obtained from a DR4 cell line and the deduced protein sequences of the beta 1 exons from cosmid and phage clones. A conserved element including the promoter and signal sequence is found at the 5' end of each of the 3 DR beta genes. Additionally, this element occurs three more times in the DR region, raising the question of whether additional beta chain genes might be found. The DQ region contains 2 pairs of genes, 1 of which encodes the DQ antigen. The 2nd pair of genes, called DX alpha and beta, appears to be capable of expressing a DQ-related product, although, to date, there is no evidence for its expression. The DP region also contains 2 pairs of genes. One pair encodes the DP antigen while the 2nd alpha-beta pair is shown to be composed of pseudogenes. The location of polymorphic regions in these genes and aspects of their relationship to the serology, evolution, and function of the class II MHC are discussed. The control of expression of class II genes by gamma-interferon has been examined. The promoters of class II genes are characterized by two conserved sequences common to all alpha and beta chain genes as well as by conserved sequences specific for either alpha or beta chain genes. In addition to studies of expression by DNA-mediated gene transformation, a system for the gene transfer of MHC antigens utilizing transmissible retrovirus vectors is described. Retrovirus vectors have been used to transmit DR alpha, DR beta, and the invariant chain (gamma) sequences to recipient cells with resultant expression of these proteins.

HLA class I genes: from structure to expression, serology and function

HLA class I genes have been isolated from phage and cosmid libraries and assayed by transfection into murine L cells. The transfection step proved to be very important because of the large number of genes (and pseudogenes) in this family. All functional genes characterized so far in this way are "classical" class I genes, i.e. members of the HLA-A, -B or -C families. Three of these have been sequenced (HLA-A3, -Aw24; HLA-Cw3) in addition to the pHLA 12.4 pseudogene. Sequence comparisons indicate, in particular, extreme conservation of the 3' non-coding region between allelic HLA-A locus genes; the general organization of all these genes (8 exons) is very similar. Restriction mapping around the functional genes has been performed to investigate the degree of conservation (e.g. between HLA-A3 regions from 2 different individuals) and examine allelism at the DNA level (e.g. between HLA-A3 and HLA-Aw24 regions). Exon shuffling experiments followed by serological analysis of the expressed product indicate that, as expected, specificities are determined by the first two domains of the molecule. However, further constructs show that as soon as a single exon is exchanged most specific reactivities disappear. CTL analysis of murine cells expressing HLA molecules has run into many difficulties but still holds promise for the study of structure-function relationships in this system.

Production and characterization of a unique monoclonal antibody against human B cells (33.2.1)

A monoclonal antibody specific for a polymorphic antigen on human B cells (33.2.1) was produced and characterized. By flow cytometry, 33.2.1 was found to react with peripheral blood B cells, monocytes, and Epstein-Barr virus (EBV)-transformed B-cell lines, but not with peripheral blood T cells, mitogen-activated T cells, or allo- or autoactivated T cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that 33.2.1 recognizes a noncovalently bound bimolecular complex composed of an alpha chain of about 32 kDa and a beta chain of about 28 kDa. The failure of anti-HLA-DR, anti-Leu-10, and anti-HLA-DC1 to remove the 33.2.1 antigen by sequential immunoprecipitation suggests that 33.2.1 recognizes a distinct molecule rather than a different epitope on either HLA-DR or DS/DC/MB. In T-cell-independent B-cell activation systems, preincubation with 33.2.1 markedly inhibited RNA and DNA synthesis as well as polyclonal Ig production. In contrast, anti-HLA-DR was inhibitory only when it was present throughout the culture, but not when it was used for preincubation. Anti-Leu-10 led to only moderate inhibition. These results suggest that 33.2.1 recognizes a unique Ia-like antigen critical for B-cell activation.

Specificity of monoclonal antibodies directed against human and murine class II histocompatibility antigens as analyzed by binding to HLA-deletion mutant cell lines

The specificity of 70 monoclonal anti-Ia monoclonal antibodies (MoAbs) (18 mouse allo-induced and 52 rodent anti-human) was studied with a panel of 17 HLA-deletion mutants that were derived from a single parent line and vary in expression of Ia antigens due to deletion of different subregions of HLA. MoAb binding was analyzed both by ELISA and flow microfluorometry. Characterization of the MoAbs with respect to specificity for products of subregions of a DR1-DC1-SB2 haplotype revealed great complexity. Many antibodies were quite specific for DR-linked determinants (26 MoAbs), DC-linked determinants (5 MoAbs), or determinants indistinguishable from SB (4 MoAbs). However, many MoAbs bound to products of more than one subregion: DR + SB (+/- weak DC) (22 MoAbs); DR + DC (3 MoAbs); or DR + DC + SB (1 MoAb). Furthermore, a number of the MoAbs bound unequally to products of the two HLA haplotypes analyzed, particularly among those recognizing DC1-linked determinants and the murine alloinduced MoAbs. Finally, despite strong structural homologies of murine I-A to human DC and murine I-E to human DR, the intraspecies cross-reactions of MoAbs do not closely follow that pattern. These data: (1) illustrate the usefulness of HLA-deletion mutant cell lines for analysis of the specificity of MoAbs and for delineation of HLA subregions; (2) demonstrate the great diversity of MoAbs specific for class II molecules and the high frequency of MoAbs that bind to products of more than one Ia subregion, particularly DR and SB. In view of such complexity, many (perhaps most) MoAbs cannot be relied on to unambiguously identify products of a particular Ia subregion, without extensive characterization.

Cellular distribution of a human I-A-like (DS/DC) antigen on normal and neoplastic lymphoid cells

Previous biochemical studies have shown that B cell specific, monoclonal antibody, McAb 33.1, reacts with a class II antigen that represents a human analogue of murine I-A (DS/DC) antigens (J. Exp. Med. 158:1924, 1983). McAb 33.1 recognizes a polymorphic human B lymphocyte specific antigen present on mu+, B1+ peripheral B cells, B lymphoid cell lines, activated B cells, and neoplastic B lymphoid cells. Of 100 HLA-D/DR typed EBV-transformed lymphoblastoid cell lines tested, only those from DR3,3 and DR7,7 individuals failed to react with McAb 33.1. The 33.1 antigen is present at lower concentrations on B cells from blood, tonsil, spleen, and lymph node when compared to B cell lines. By contrast, the antigen is not detectable on blood T lymphocytes, T cell lines, or mitogen activated T cells and it is absent on monocytes of some individuals or is present only on a minor subpopulation (approximately 20%). McAb 33.1 should facilitate the functional, structure, and molecular dissection of the human Ia system.

Lymphocytic lymphoma/B-chronic lymphocytic leukaemia--an immunohistopathological study of peripheral B lymphocyte neoplasia

Twenty seven patients with malignant lymphoma of lymphocytic type/B-chronic lymphocytic leukaemia (ML, L/B-CLL, Kiel classification) diagnosed from lymph node and splenectomy specimens were studied histologically and immunologically. Lymph node biopsies showed a diffuse effacement of normal architecture by small round lymphocytes usually with scattered proliferation centres (PC). A1 spleens showed white pulp with or without red pulp involvement, sometimes with tumour nodules present. PC-like cells or PC were only found in the white pulp or tumour nodules. Studies of 13 specimens using the ABC immunoperoxidase technique on frozen sections with a large panel of monoclonal antibodies showed that although a part of the monoclonal B cell neoplasm, the proliferation centres or splenic white pulp have a different phenotype from the surrounding cells. Some of these phenotypic changes are similar to those reported with in vitro induction of "maturation" of ML, L/B-CLL cells. The implications for normal B-cell development are discussed. In contrast to reported peripheral blood findings, T cells, predominantly of T helper phenotype in lymph nodes, were present but usually not numerous.

The detection of HLA-DR, MB and MT determinants on purified class II molecules by inhibition of microcytotoxicity

An assay has been developed which makes it possible to determine the HLA allospecificities carried by molecules in purified fractions of detergent lysates from EBV-transformed human lymphocytes. It is based on inhibition of the standard microlymphocytotoxic test used for identifying HLA class I and II antigens with alloantisera. Soluble cell membrane products from EBV-transformed cell lines homozygous for the HLA region gave specific inhibition of standard typing antisera. The test requires preincubation of microliter volumes of soluble antigen preparations maintained in 0.05% NP-40 with selected antisera prior to adding EBV-transformed cells as target cells. It was possible using this assay to follow isolation of the structurally related human class II molecules bearing the MB and DR specificities. Detergent lysates of cells were fractionated on affinity columns prepared from monoclonal antibodies directed against distinct class II antigens. Eluates from these columns contained the expected DR and MB specificities. The assay is easy to perform, highly reproducible and allows multiple determinations.

Homozygous deletions that simultaneously eliminate expressions of class I and class II antigens of EBV-transformed B-lymphoblastoid cells. I. Reduced proliferative responses of autologous and allogeneic T cells to mutant cells that have decreased expression of class II antigens

Mutant human B-lymphoblastoid cell lines, 721.174 and 721.180, that have greatly reduced expressions of known class I and class II HLA antigens were produced by two cycles of gamma-ray mutagenesis followed by selection for HLA antigen loss. Residual binding of monoclonal antibodies directed against class II antigens was negligible except for 10% residual binding of SB-binding antibody ILR1. However, deletion of SB was functionally complete as indicated by failure of the mutants to stimulate proliferation of SB-primed lymphocytes. Residual binding of monoclonal antibodies directed against class I "framework" determinants was reduced by 90-95%. However, the binding of monoclonal antibodies directed against beta 2-microglobulin and against the A2 epitope recognized by monoclonal antibody BB 7.2 was about 20% of normal. The identities of the residual class I-like antigens are unknown. The mutants retained full expression of the EBV-induced EBVCS antigen. Mutants 721.174 and 721.180 have lost most, but definitely not all, of their capacity to stimulate primary allogeneic and autologous lymphoproliferative responses. Therefore, the mutants still express antigens other than those that are presently known to stimulate lymphocyte proliferation. By means of studies of the present sort, and in future studies on expression of transferred HLA genes, mutants 721.174 and 721.180 promise to be useful in molecular and functional analysis of MHC-region-encoded gene products and their genetic regulation.

HLA loss variants of a B27+ lymphoblastoid cell line: genetic and cellular characterization

Variants of a lymphoblastoid cell line, LCL 526 (SB3 MB1 DR1 B44 C5 A2/SB4 MT4 DR4 B27 C2 A24), which lost various HLA specificities were selected with monoclonal antibodies and complement using a method developed by Kavathas et al. (PNAS 77:4251, 1980). Using alpha B27 monoclonals, 8 B27 only loss mutants and 4 B27 haplotype multiple loss mutants were generated. The parental LCL 526 and two of the B27- mutants were used to select alpha B27 CTLs. The selection of six A2 loss, one A2-C5 loss, and 14 A2 haplotype multiple loss variants as well as secondary selection on haplotype loss variants to obtain A null, B null, DR null, and total A, B, C, null variants is also described. The usefulness of these mutants for the study of the relationship between B27 and disease and as two new haplotypes for immunologic, genetic, and molecular research is discussed. These mutants are available to other researchers.

Separation of four class II molecules from DR2 and DRw6 homozygous B lymphoid cell lines

Four human class II molecules, one FA, one DC1, and two DR-like molecules, were isolated from DR2 and DRw6 homozygous cell lines by means of a variety of monoclonal antibodies and were compared with each other by two-dimensional (2-D) gel electrophoresis. Anti-DR2 or anti-DR3 + 5 + w6 sera immunoprecipitated two distinct light chains (L1 and L2) and one heavy chain (H1) from a DR2 or DRw6 homozygous cell line, respectively. One or both of these two class II molecules were also immunoprecipitated by "DR-specific" monoclonal antibodies and were considered to constitute a "DR" family of molecules. Three DC1-specific monoclonal antibodies, SDR4.1, Tu22, and PLM5, immunoprecipitated a set of heavy (H2) and light (L3) chains distinct from those of two DR-like molecules. The heavy chains of the DC1 antigens from DR2 and DRw6 cell lines were indistinguishable, whereas the light chains were structurally distinct from each other. A fourth molecule, FA, was identified by a novel monoclonal antibody and was also detected by two additional antibodies, Tu39 and SG171, that blocked the SB-specific T-cell proliferative response. The FA light chain (L4) was distinct from those of the former three antigens on both cell lines, whereas the FA heavy chain was indistinguishable from the DC1 heavy chain (H2) in this 2-D gel analysis. Thus, four light chains and two heavy chains were isolated from both DR2 and DRw6 homozygous cell lines. A possible gene-antigen organization of the DC-like antigens was also discussed.

Primary structural sequence polymorphism in the human class II MHC antigen 33.1

Monoclonal antibody 33.1 defines a non-DR, class II, human major histocompatibility complex antigen, 33.1, which appears to be distinct from other class II antigens in its cellular distribution and primary structure. To characterize the structure more fully and to determine the degree of polymorphism within 33.1, a comparative N-terminal sequence study has been undertaken using a series of ten B lymphoblastoid cell lines with different DR and MB types. The results confirm that both the alpha and beta chains of 33.1 are homologues of the corresponding chains of the murine I-A antigen and indicate that while 33.1 does not appear to be identical with MB, it is closely related. Sequence analyses revealed two major variants of 33.1, corresponding to cells with specificities MB1 and MB3, respectively. Within each MB type, other polymorphisms have been detected. Cells that are MB2 do not react with monoclonal antibody 33.1. Suggestive evidence is presented that monoclonal antibody 33.1 reacts predominantly with the beta chain of the antigen. The preferential expression of 33.1 on activated B cells suggests that expression of at least the 33.1 beta chain gene is greatly enhanced in the course of B-cell activation, but the specific function of 33.1 remains to be determined.

Highly polymorphic products of both HLA-DR and HLA-DQ genes contribute to the polymorphism of the HLA-DRw13 haplotype

We studied the polymorphisms of HLA-DR and HLA-DQ products from HLA-DRw13 haplotypes by analyzing the restriction of influenza A-specific cloned T cells from an HLA-DRw13,DQw1,Dw19 homozygous individual. The results show that some functional epitopes, which can be borne by either HLA-DR or HLA-DQ molecules, are strictly correlated with the HLA-Dw19 subtype of HLA-DRw13. This clearly indicates that both HLA-DR and HLA-DQ products contribute to the HLA-Dw19 subdivision of HLA-DRw13. At least two different restricting epitopes are borne by DR products: one is correlated with the HLA-DRw13 serologically defined specificity, which includes Dw19 and Dw18 haplotypes; the other is correlated with the only HLA-Dw19 subtype of HLA-DRw13. Restricting epitopes borne by DQ molecules have been found on Dw19 cells only. DQ-restricted clones were unable to react with DQw1 APC of any other haplotypes tested, including DR1, DR2-long, DR2-short, and DRw14, demonstrating a high degree of functional polymorphism among the serologically defined DQw1 specificities.