Antigen processing and presentation by EBV-carrying cell lines: cell-phenotype dependence and influence of the EBV-encoded LMP1.

Burkitt's-lymphoma (BL) lines which have maintained in vitro the tumor-cell phenotype (group-I BLs) are poor antigen-presenting cells (APC), in spite of a relatively high surface expression of MHC class II. In order to investigate the mechanism of this deficiency, we have compared group-I BL lines, their sub-lines which have progressed in vitro towards an LCL-like phenotype (group-III BLs), and EBV-transformed lymphoblastoid cell lines (LCLs), for their ability to bind and process tetanus toxoid (TT). The uptake and internalization of 125I-labelled TT was equivalent in the 3 cell types.

LAK cells release a novel form of directly acting TGF beta, tightly bound to a high molecular weight carrier(s).

We showed in previous work that LAK cell supernatants contain a large molecular weight factor with toxic activity for A375 melanoma and other cell lines. The factor, Fr1, was identified tentatively as TGF beta-related, since its activity was abolished by anti-TGF beta serum. This relatedness is further confirmed in the present work, which demonstrates that, like TGF beta, Fr1 stimulates the release and deposition of fibronectin and induces morphological changes indistinguishable from those induced by TGF beta.

Cloning and characterization of the latent membrane protein (LMP) of a specific Epstein-Barr virus variant derived from the nasopharyngeal carcinoma in the Taiwanese population.

A DNA fragment containing Epstein-Barr virus (EBV) terminal fragment sequence was obtained from a genomic library of nasopharyngeal carcinoma (NPC). One of the clones (clone 1510) contained the gene encoding latent membrane protein (LMP). Sequence analysis revealed that this gene had 95% homology with the LMP sequence of the B95-8 strain.

Degenerative changes in the A375 melanoma line induced by transforming growth factor beta 1.

A375 human melanoma cell cultures grown in the presence of TGF beta contained greatly reduced cell numbers and exhibited drastic alterations in cell morphology compared to the control cultures. Preincubation of the cells with the cytokine for only 18 h was sufficient to induce these changes irreversibly. Examination of TGF beta-treated cells in the electron microscope revealed large numbers of lipid-filled vacuoles in the cytoplasm, greatly contracted nuclei and some loss of the otherwise abundant microvilli.

A high molecular weight cytotoxic lymphokine in supernatants of lymphokine-activated killer cells cross-reacts with transforming growth factor beta.

Supernatants of lymphokine-activated killer (LAK) cells were highly cytotoxic for melanoma A375 cells. A high-molecular-weight fraction was isolated from such supernatants by gel filtration on an S-300 Sephacryl column (Fraction 1; Fr1). The cytotoxic activity in Fr1 was heat- and acid-resistant and was completely abolished by a rabbit antibody against TGF-beta.

Cross-reactivity between the EBNA-1 p107 peptide, collagen, and keratin: implications for the pathogenesis of rheumatoid arthritis.

An unusually heavy load of Epstein-Barr virus (EBV) infection and autoimmunity to collagen are believed to be contributing factors to the pathogenesis of rheumatoid arthritis (RA). The present report presents data showing that p107, the major epitope of the EBV-encoded EBNA-1 antigen, cross-reacts with denatured collagen (DC) and keratin (K), suggesting a new likely link among RA, EBV-1, and these autoantigens. A radioimmunoassay using antigen-coated microtiter plates was used to demonstrate antibodies in sera of patients with RA and sera of healthy donors against p107, DC, and K.

Culture supernatants of lymphokine-activated killer (LAK) cells contain a high-molecular-weight cytotoxic lymphokine.

Supernatants of human lymphokine-activated killer (LAK) cells grown in vitro were tested for cytotoxic activity against several mouse and human neoplastic cell lines. All LAK preparations tested (14/14) exhibited cytotoxic activity (40-90% killing of the target cells). Sephacryl S-300 Gel filtration experiments indicated that the biological activity of the LAK supernatant is associated with molecular moieties ranging from 800 kDa or more, to less than 10 kDa.

Antibodies in human sera against the Epstein-Barr virus encoded latent membrane protein (LMP).

Antibodies reactive with the Epstein-Barr (EBV)-encoded latent membrane protein, LMP, were detected in human sera. Membrane fractions of the EBV-carrying Raji cells and a fusion protein (LMFP), that represents the carboxy part of LMP, were used as antigens. These were assayed by the reduction of the leukocyte migration inhibition (LMI) reaction.

Proteins in normal and malignant cells, cross-reacting with the latent membrane protein encoded by Epstein-Barr virus.

Human B lymphocytes transformed by infection with the Epstein-Barr virus (EBV) express a new membrane protein of 63 kDa (latent membrane protein, LMP) encoded by the virus. The function of this protein in the virus-cell interaction is not known. In this work we have identified in EBV- human and mouse cell molecules which cross-react with LMP.

Stable transfection of a human lymphoma line by sub-genomic fragments of Epstein-Barr virus DNA to measure humoral and cellular immunity to the corresponding proteins.

An Epstein-Barr virus (EBV)-negative human lymphoid B-cell line, DG75, was stably transfected with recombinant selection vectors that carry a subfragment of the BamHI WYH region (nucleotides 44664 to 50628), the BamHI K fragment, or a subfragment of the EcoRI D region (nucleotides 166614 to 170149) of B95-8 EBV DNA. These fragments contain the coding exons for the EBV-determined nuclear antigens EBNA2 and EBNA1, and the membrane antigen LMP, respectively. Antigen expression of the cells was detected by immunofluorescence.

Down-regulation of the EBV-encoded membrane protein (LMP) in Burkitt lymphomas.

A radioimmunoassay (RIA) has been developed and used to determine the expression of LMP-a membrane protein encoded by the LT3 region of the Epstein-Barr virus (EBV) genome-in cell lines of various origins. The RIA was highly sensitive, specific and reproducible. All EBV-negative cell lines were LMP-negative and 18 of 21 EBV-carrying cells were LMP-positive.

A radioimmunoassay for the diagnosis of malaria.

A newly developed radioimmunoassay for the diagnosis of malaria has been tested in South Africa. The radioimmunoassay is an antibody binding-inhibition assay, based on a monoclonal antibody (D5) cross-reacting with Plasmodium berghei and P. residual binding activity was tested on antigen-coated microtiter plates.

(Auto)antibodies in human breast cancer sera against antigens associated with breast cancer cells, detected by immunoblotting.

Sera of patients with breast cancer (as well as control normal sera and sera of patients with ovarian cancer or melanoma) were screened for the presence of antibodies against antigens expressed by the MDA breast cancer cell line. The techniques employed were radioimmunoassay with radioiodinated protein A and immunodotting with peroxidase-conjugated anti-human immunoglobulin antibodies. Sera reacting strongly by immunodotting were subsequently tested against antigens of the MDA and T47D cell lines in immunoblotting experiments.

Epstein-Barr virus (EBV) antigen-specific leukocyte migration inhibition (LMI) in infectious mononucleosis (IM). I. Kinetics and response to a membrane protein on EBV-transformed cells.

Cell-mediated immune response of mononucleosis (IM) patients to Epstein-Barr virus (EBV)-determined antigens was measured by the leukocyte migration inhibition (LMI) assay. Patients in the acute phase of the disease failed to respond to partially purified nuclear antigen, EBNA, or to cell extracts that contained EBNA as the predominant EBV antigen. They showed a strong specific response to cell extracts enriched in early antigen (EA) and virus capsid antigen (VCA).

Leukocyte migration inhibition demonstrates a human T-cell response to a membrane protein expressed in latent Epstein-Barr virus infection.

Leukocyte migration inhibition tests show that lymphocytes of Epstein-Barr virus-seropositive individuals recognize a Raji cell membrane antigen and a membrane protein encoded by Epstein-Barr virus in latently infected cells. Antiserum against the latter blocks the leukocyte migration inhibition triggered by both preparations, suggesting that the two antigens are associated with the same protein complex.

Serial circulating immune complex values and development of metastatic disease in breast cancer and malignant melanoma patients.

A polyethylene glycol precipitation technique was used to determine the levels of circulating immune complexes (CIC) in breast cancer and melanoma patients. All patients in the study had undergone surgery and were free of distant metastatic disease. CIC were measured at two to four time intervals, of 3 to 6 months each, over an average follow-up period of 13.

Detection of Plasmodium falciparum using a radioimmunoassay based on a crossreacting, monoclonal anti-P. berghei antibody-P. berghei antigen system.

An antibody binding-inhibition test is described, which allows the detection of P. falciparum in red blood cells (RBC) infected in vitro, using a crossreacting, monoclonal anti-P. berghei antibody and P.

Use of a monoclonal, anti Plasmodium berghei antibody, cross reacting with P. falciparum, for the detection of P. falciparum in in vitro infected blood.

This report describes an immunoradiometric assay for Plasmodium falciparum in infected blood, based on a cross-reacting monoclonal antibody (mAb) raised against P. berghei. In this assay, binding of the mAb to intact P.

Detection of an Epstein-Barr virus-associated membrane antigen in Epstein-Barr virus-transformed nonproducer cells by leukocyte migration inhibition and blocking antibody.

Soluble membrane fractions derived from Raji cells trigger lymphocytes of Epstein-Barr virus (EBV)-seropositive, but not EBV-seronegative, individuals to release a lymphokine that inhibits leukocyte migration. The reaction can be blocked by the sera of patients with EBV-DNA-carrying tumors, Burkitt lymphoma, or nasopharyngeal carcinoma. Absorption of these sera with EBV-positive, but not EBV-negative, cells abrogates their blocking activity.

Anti-red blood cell autoantibodies induced in rat by Plasmodium berghei infection bind to a cross-reacting determinant present also in other cell types.

It has been previously shown that rats injected with red blood cells (RBC) infected with Plasmodium berghei make autoantibodies reacting with normal rat RBC as demonstrated by a staphylococcal protein A binding assay. In this study, the serum of the infected rats was found to contain also antibodies to several other types of rat cells (lymphoid, liver, and kidney cells and brain tissue) as well as against RBC and lymphoid cells of mice and sheep, but not of man. Rat, mouse, and sheep RBC and rat and mouse lymphocytes absorbed completely the antibodies to rat RBC, suggesting that a single, cross-reacting determinant might be involved in these reactions.

Levels of fibrinogen/fibrin degradation fragment E and related substances in sera and effusions of patients with malignant disease.

A radioimmunoassay (RIA) was developed and used to determine the level of fragment E [a fibrinogen/fibrin degradation product (FDP)] and of fragment-E-containing substances (FES) in sera and effusion fluids of patients with malignant diseases. Sera of patients with other diseases and sera of healthy individuals served as controls. Results were expressed as units/ml (U/ml), one unit being equivalent to 40 ng pure fragment E.

Preliminary field trial of a radioimmunoassay for the diagnosis of malaria.

A radioimmunoassay (RIA) has been developed for the detection of Plasmodium falciparum in infected blood. The assay is based on the ability of solubilized, infected red blood cells (RBC) (P. falciparum "antigen") to combine with anti-P.