The monoclonal antibody HCA2 recognises a broadly shared epitope on selected classical as well as several non-classical HLA class I molecules.

HCA2 is a widely used monoclonal antibody, thought to be highly selective for HLA-A and -G heavy chains. We demonstrate here that it also shows affinity to HLA-B73 and HLA-E molecules on intact cells. By comparing the differences in the amino acid (AA) sequences of several HLA class I alleles that are either recognised or not recognised by HCA2, a likely epitope of HCA2 has been deduced. It extends from position 76 to position 83 of the alpha1-domain. In intact cells, the solvent-exposed AA in positions 76 (Ala, Val, or Met), 80 (Asn or Thr) and 83 (Gly) are likely to constitute the recognition region. Inhibition experiments with peptides spanning the region of the alpha1-domain from position 74 to 85 of various HLA class I heavy chains prove that HCA2 recognizes a broadly shared epitope on HLA-E, -F and -G molecules as well as selected HLA-A, -B and -C antigens.

Do monoclonal antibodies Tü15 and Tü67 detect heterogeneity of human transferrin receptor molecules?

The possible molecular heterogeneity of human transferrin receptors was analyzed using two murine monoclonal antibodies, Tü15 and Tü67. Both reagents precipitated from lysates of 125I-labeled HL-60 cells a major component of 88 kDa which could be identified as the transferrin receptor by comparison with the proteins detected by monoclonal antibody OKT9. Although sequential immunoprecipitations appeared to demonstrate molecular heterogeneity of transferrin receptors, since the Tü15-reactive species were fully included in the Tü67-positive population, but not vice versa, the possible association of Tü15-reactive molecules with transferrin receptor is also discussed.

Rapid preparation of multiple cell samples for immunofluorescence analysis using microtiter plates.

A method is described which allows incubation, washing and staining of cells for immunofluorescence analysis to be carried out in microtiter plates. Comparison of this procedure with the conventional protocol, carried out on normal and leukemic human peripheral blood cells, reveals 5 major advantages. (1) Only 2.5 X 10(5) viable cells are needed for testing a particular antiserum. (2) The amount of reagents needed is 1/4 of that used in the conventional method. (3) Damage to cells is reduced to a minimum by shorter processing times and gentler centrifugation steps. (4) A large number of samples can be processed at the same time in an identical and reproducible manner. (5) The cost of an experiment is considerable reduced.

Microheterogeneity in HLA-B35 alleles influences peptide-dependent allorecognition by cytotoxic T cells but not binding of a peptide-restricted monoclonal antibody.

Strong peptide dependency of HLA-B*3501-specific alloreactive T-cell clones was observed in the recognition of cells bearing closely related B35 variants. The single amino acid exchange in the beta-pleated sheet of B*3503 completely abolished the responses of all clones, whereas an amino acid exchange in the alpha 2 helix of the newest B35 member (B*3508) only altered allorecognition of one T-cell clone, demonstrating the differential impact of these positions on peptide binding to B35 molecules. In contrast to T cells, a mAb (TU165) recognizing the B35 specificity in a peptide-dependent manner bound to the B35 variants irrespective of their sequence heterogeneity. However, quantitative binding differences were detected with cells bearing the same B35 alleles. This is most likely due to variations in the amount of peptide(s) that associates with B35 and forms the ligand seen by this mAb. These results reveal how naturally occurring single amino acid substitutions have led to generation of functionally distinct molecules of another multimember HLA class I cluster.

Structurally diverse forms of HLA-B27 molecules are displayed in vivo in a cell type-dependent manner.

The formation of a trimeric complex, composed of heavy chain (HC), beta(2)-microglobulin (beta(2)m) and antigenic peptide, is generally believed to be a prerequisite for the expression of HLA class I molecules at the cell surface in vivo. Therefore, a possible role in immunological processes for HC/beta(2)m complexes devoid of peptide has not been seriously considered. Using a novel HLA-B*2705-transgenic rat model and monoclonal antibodies that distinguish between structurally different forms of HLA-B27 molecules, we demonstrate here that class I molecules which appear to lack antigenic peptides are expressed in abundance on a variety of cell types in lymphoid organs. These results imply a role for structurally diverse, possibly empty, MHC molecules in physiological T cell selection which has so far not been sufficiently appreciated.

Characterization of a monoclonal anti-Bw4 antibody (Tü109): evidence for similar epitopes on the Bw4 and Bw6 antigens.

The production and serologic, as well as immunochemical properties of a cytotoxic murine IgG monoclonal antibody (Tü109) that precipitates HLA-class I molecules, are described. In the microcytotoxicity assay Tü109 supernatant was demonstrated on a panel of 424 HLA-ABC, -DR, -DQ, -MT typed normal Caucasian blood donors to define an epitope on HLA-B locus molecules in great association with the supertypic specificity Bw4. Reactivity of supernatant showed MHC linked inheritance of the Tü109 determinant and discriminated the HLA-Bw4/Bw6 associated HLA-B locus split antigens. Weak or lack of binding on lymphocytes from some HLA-Bw4 heterozygous individuals, particularly typing for HLA-Bw44, appeared to be due to qualitative and/or quantitative variations of HLA-B locus molecules on the cell surface. With Tü109 ascites fluid, however, extra-reactivity on all HLA-Bw6+ cells was demonstrated. Preferential binding of supernatant to HLA-Bw4, but reactivity of ascites fluid with HLA-Bw6+ molecules in addition, was furthermore confirmed by IEF analysis of antigens immunoprecipitated with Tü109 from cell lysates. Thus the antibody may help to analyze the evolutionary relationship of the diallelic specificities Bw4 and Bw6.

Surface expression of HLA-C antigen by human extravillous trophoblast.

In this paper definitive evidence that the classical class I product, HLA-C, is expressed on the surface of normal trophoblast cells is provided. HLA-C transcripts were sequenced from cDNA isolated from first trimester trophoblast cells obtained by flow cytometric sorting. Both paternal and maternal alleles were transcribed. HLA-C proteins were demonstrated by biochemical analysis and found on the cell surface in association with beta(2)-microglobulin. Upregulation of cell surface HLA-C but not HLA-G expression after interferon (IFN)-gamma treatment was demonstrated by flow cytometric analysis. Immunohistology has confirmed HLA-C is expressed by all extravillous subpopulations in vivo. The question of whether trophoblast HLA-C molecules interact with decidual NK cells expressing killer Ig-like receptors (KIR) has also been addressed. Our results demonstrate that extravillous trophoblast expresses at least two HLA class I molecules, HLA-G and HLA-C on the cell surface.

Analysis by sequential immunoprecipitations of the specificities of the monoclonal antibodies TU22,34,35,36,37,39,43,58 and YD1/63.HLK directed against human HLA class II antigens.

The monoclonal antibodies (MOABs) TU22, TU34, TU35, TU36, TU37, TU39, TU43, TU58 and YD1/63.HLK were used to identify subpopulations of class II antigens encoded by the human major histocompatibility complex. Since all MOABs reacted with B lymphocytes of HLA-DR1-8 homozygous as well as all heterozygous cells tested, they recognize monomorphic determinants, with the possible exception of TU58 and YD1/63.HLK which do not fix complement. As shown by radioactive binding assays and immunoprecipitations of labeled chains, 3 MOABs reacted strongly and 3 others weakly with isolated beta-chains, and the former also bound alpha-chains, albeit very weakly. Immunoprecipitations with the MOABs from 125I-labeled KR3598 cells (Dw5, DR5, MT2, MB3 homozygous, SB2, SB4) demonstrated that at least 4 different subpopulations of class II antigens were present in the lysate. Possibilities to reconcile these biochemical data with the reactivity of the MOABs with HLA mutant cell lines and with functional as well as tissue distribution studies are discussed.

Kinetics of restoration of interferon production after bone marrow transplantation in man.

Peripheral blood mononuclear cells (PBMC) from 21 patients after bone marrow transplantation (BMT) were studied for their capacity to produce interferon (IFN) in vitro. The basal and IFN-stimulated 2-5 A synthetase activity was also investigated as a marker of the cells' ability to respond to exogenous IFN. All but one patients received cyclosporin A as a prophylaxis against graft-versus-host disease (GVHD). GVHD was diagnosed in three patients. IFN production in response to stimulation with phytohemagglutinin or poly I:C was not detectable in most patients without GVHD until 7 months after grafting. However, in a proportion of recipients without GVHD, studied early after BMT, transient normal IFN production was observed. In contrast to patients without GVHD, PBMC from patients with GVHD produced stable high levels of IFN when stimulated in vitro. The impairment of IFN production did not correlate with conditioning regimens, infection, plasma cyclosporin levels or the lymphocytes' blastogenic response to the mitogens. Addition of interleukin-2 (IL-2) to culture medium of fresh unresponsive PBMC restored only partially the defective IFN production. Similarly, T-cell lines propagated in IL-2 conditioned medium, from unresponsive PBMC, produced low levels of IFN gamma when stimulated with PHA. The basal activity of 2-5 A synthetase in PBMC from patients without GVHD could not be stimulated, during the first 3 months after BMT, by the cultivation of cells with IFN alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical characterization of round cells in human semen using monoclonal antibodies and the APAAP-technique.

Round cells of 42 ejaculates were characterized by their surface antigens using monoclonal antibodies and the immunocytochemical APAAP-technique. In this way immature germ cells, polymorphonuclear leukocytes, lymphocytes and their subpopulations could be distinguished. It was also attempted to correlate the incidence of these cells, sperm parameters and other clinical data.

HLA antigen expression at the single cell level on a K562 X B cell hybrid: an analysis with monoclonal antibodies using bacterial binding assays.

The influence of different genetic environments on the expression of HLA complex-controlled antigens has been investigated using cell lines with various defects in the synthesis of these molecules and a somatic cell hybrid derived from them. A very sensitive bacterial binding assay allowing simultaneous evaluation of the morphology of a given cell and the quantity of a surface molecule has been developed for these studies. The fetal erythroid cell line K562, the Burkitt's lymphoma-derived cell line DAUDI, and their hybrid DUTKO1 have been employed. K562 and the hybrid, but not DAUDI, expressed HLA-A,B,C heavy chains as detected by the monoclonal antibody W6/32.HL, while two monoclonal antibodies (TU48 and 2BC4) against the supertypic specificities HLA-Bw4 and Bw6 showed no reactivity. The presence of human Ia-like antigens on the cell surfaces was investigated with a panel of eight monoclonal antibodies. K562 cells were completely unreactive, and DAUDI cells gave the expected positive reaction, but about 1% or less of the cells in the DUTKO1 population appeared to express these antigens as well. We discuss possible reasons for the failure to detect HLA-B antigens with monoclonal antibodies and the lack of complete "dominance" of the K562 genome in the hybrid cell line.

Hodgkin and Sternberg-Reed cells contain antigens specific to late cells of granulopoiesis.

The results of a recent investigation, in which an antiserum specifically directed against Hodgkin (H) and Sternberg-Reed (SR) cells was prepared, indicated the existence of a granulocytic cell-specific antigen on H and SR cells. In the present study, a large series of biopsies from patients with Hodgkin's disease were subjected to immunostaining with monoclonal mouse antibodies raised against acute myelomonocytic leukemia (AMML) cells. Among seven hybrids that secreted antibodies showing reactivity to AMML cells but not to Daudi cells, there were three (TU5, TU6 and TU9) whose antibodies selectively stained formalin resistant antigens in cells of granulopoiesis. The strongest staining was found in the more mature cells; only a few promyelocytes stained very faintly with TU9, H and SR cells showed distinct staining for TU9 in 57 (76%) of the 75 tested cases of Hodgkin's disease, whereas TU5 and TU6-reactive H and SR cells were found in only 35 cases (47%). All cases of the nodular sclerosis type and almost all cases of the mixed cellularity type contained TU9-reactive H and SR cells, although the percentage varied from case to case. TU9-reactive H and SR cells were demonstrated in nine of 12 cases of the lymphocyte depletion type and in eight of 21 cases of the lymphocyte predominance type. The presence of granulocytic cell-specific antigens in H and SR cells in most of the cases of Hodgkin's disease suggest that (1) H and SR cells (including the lacunar cell variant) are not heterogeneous, but rather homogeneous in origin and nature, at least in a majority of cases, and (2) H and SR cells are more closely related to cells of the granulocytic cell lineage than to any other type of cell of the hemato-lymphoid system.

Identification of human spermatozoa antigens using monoclonal antibodies and the alkaline phosphatase anti-alkaline phosphatase-technique.

Both cytoplasmic and surface-membrane antigens of human spermatozoa were detected by means of monoclonal antibodies (MoAbs) and of the alkaline phosphatase anti-alkaline phosphatase- (APAAP-) technique. Several advantages of this technique for the identification of sperm could be demonstrated. The labeling of cytocentrifuge preparations from 16 ejaculates proved the presence of glycosphingolipids, nuclear and mitochondrial antigens of spermatozoa. However, there were no HLA-molecules and other leukocyte antigens on sperm cells.

Immunoelectron microscopy of human spermatozoa.

A number of immunocytochemical methods using various markers for electron microscopy have been developed in recent years. The immunogold technique has been especially effective in histotopochemical studies. The value of this technique for demonstrating sperm antigens results from the high electron density of gold, which makes it easily detectable under the electron microscope. The high resolution of the electron microscope permits precise localization of immunologic reactions in the sperm cell. Light microscopy findings can thus be elucidated. We tested a number of monoclonal antibodies that react with sperm antigens. Of three techniques for preparing the spermatozoa, the pre-embedding method and marking of cryoultra-microtome sections proved best.

Soluble T cell receptor-like properties of an HLA-B35-specific monoclonal antibody (TU165).

A mouse monoclonal antibody of IgM class (TU165) was produced using Epstein-Barr virus (EBV)-infected mutant cells derived from the human BJAB-B95.8.6 cell line as immunogen. Binding studies with several HLA deletion mutant cell lines indicated that TU165 recognized the HLA-B35 molecule. In a panel of 89 EBV-transformed lymphoblastoid cell lines, all HLA-B35+ cells (n = 24) reacted with TU165 while all but two HLA-B35- lines (n = 65) were unreactive (r = 0.95). Surprisingly, peripheral blood lymphocytes of HLA-B35+ donors were unreactive; however, strong enhancement of TU165 recognition was observed with B cells of one of these individuals after transformation with EBV (B95.8 strain). Transfection of both HLA-B35 and human beta 2-microglobulin genomic DNA into mouse P815 cells led to high expression of HLA-B molecules; yet, expression of the TU165 epitope was not observed. Furthermore, the EBV-negative cell line BJAB as well as the EBV-infected (P3HR1 strain) line BJAB-HR1K were only weakly reactive, whereas the BJAB-B95.8 cell line was strongly positive. These results indicate that EBV-encoded or -controlled peptide(s) must be bound by HLA-B35 antigens to create the epitope which allows efficient binding of TU165.

Direct selection of a human antibody fragment directed against the tumor T-cell epitope HLA-A1-MAGE-A1 from a nonimmunized phage-Fab library.

Antitumor antibodies with the same specificity as cytotoxic T lymphocytes that recognize antigenic peptides encoded by tumor-associated genes and presented by MHC class I molecules would be valuable tools to analyze the antigenicity or target tumor cells in vivo. To obtain a human antibody directed against a peptide encoded by gene melanoma-associated antigen (MAGE)-A1 and presented by HLA-A1 molecules, we selected a large phage Fab antibody repertoire on a recombinant version of the complex HLA-A1-MAGE-A1 produced by in vitro refolding. One of the selected phage antibodies shows binding to HLA-A1 complexed with the MAGE-A1 peptide, but does not show binding to HLA-A1 complexed with a peptide encoded by gene MAGE-A3 and differing from the MAGE-A1 peptide by only three residues. Phages carrying this recombinant antibody bind to HLA-A1(+) cells only after in vitro loading with MAGE-A1 peptide. These results indicate that nonimmunized phage Fab libraries are a source of antibodies with a T cell antigen receptor-like specificity. The human anti-HLA-A1-MAGE-A1 antibody described here may prove very useful for monitoring the cell surface expression of these complexes, and eventually, as a targeting reagent for the specific immunotherapy of HLA-A1 patients bearing a MAGE-A1-positive tumor.

MHC class II antigen expression is increased in different forms of urticaria.

Urticarial reactions encompass a variety of inflammatory and immunological reactions. In order to clarify specific aspects of these processes, we analyzed the distribution and sequential expression of major histocompatibility complex II (MHC class II) molecules in tissue sections from different types of whealing reactions. Using immunohistochemical techniques and monoclonal antibodies, expression of HLA-DR, HLA-DP, and HLA-DQ was examined on resident and infiltrating cells in different skin cell compartments, comparing early with longer-lasting wheals and lesional with uninvolved skin. Sequential biopsies were studied in cold urticaria (CU). No increase of MHC class II molecule expression was found in early prick test wheals to common inhalant allergens. In CU, however, sequential biopsies demonstrated an up-regulation of MHC class II molecules within 30 min after elicitation. This was more pronounced in longer-lasting urticaria lesions of acute, chronic recurrent and delayed pressure urticaria, with HLA-DR and, to a lesser degree, HLA-DP and HLA-DQ being noted on cell infiltrates, on vascular endothelia and around nerves and sweat glands. Nonelesional skin in these types of urticaria also showed increased MHC class II expression. Longer-lasting urticarial wheals are thus associated with up-regulation of MHC class II molecules on resident and infiltrating cells, suggesting an involvement of these molecules in the pathomechanisms of these types of urticarial lesions.

Expression of HLA-A and -B antigens on differentiating U-937 cells.

Cells from the human immature monocytoid cell line U-937 were induced with 12-O-Tetradecanoyl-phorbol-13-acetate (TPA) to differentiate towards macrophage-like cells. The expression of HLA-antigens during differentiation was examined with a panel of monoclonal antibodies directed against monomorphic and polymorphic determinants. Class II antigens could be detected neither on uninduced nor on TPA-induced U-937 cells. While the expression of HLA-A3 did not change significantly during differentiation, the "supertypic" specificities HLA-Bw4 and Bw6 as well as the "private" specificity HLA-B18 could be detected only on a drastically decreased number of cells after 4 days of exposure to TPA. This may imply a selective loss of HLA-B molecules from the cell membrane and therefore a separate regulatory control of HLA-A and -B antigens.