Antibodies unrelated to Epstein-Barr virus in human sera which precipitate soluble components of cultured lymphoblasts

A technique for the identification of glycoprotein antigens in immune complexes and its application to the detection of a common glycoprotein in sera of patients with Burkitt's lymphoma and nasopharyngeal carcinoma

A new technique for the detection of glycoprotein antigens in immune complexes (IC) isolated from serum is described. The technique was developed with a model IC system consisting of ovalbumin (OVA)-rabbit anti-ovalbumin antibodies (aOVA), at 3 times antigen excess. OVA-aOVA IC added to normal human serum (NHS) were purified by absorption onto and elution from tubes coated with rheumatoid factor (RF) and were subjected to electrophoresis in polyacrylamide gels. Concanavalin A (Con A)-binding proteins were detected by treating the gels with radioiodinated Con A (125Con A), followed by autoradiography. IC isolated from sera of patients with Burkitt's lymphoma (BL) and Nasopharyngeal Carcinoma (NPC) were analyzed before and after reduction with dithiothreitol. Two closely spaced proteins of about 40 kdalton were identified in the reduced samples in 26 of 30 BL sera (86%) and in 24 of 30 NPC sera (80%) but were not seen in 30 sera of African patients with a variety of unrelated tumors nor in 12 sera of European blood bank donors.

Epstein-Barr virus-induced membrane antigens: immunochemical characterization of Triton X-100 solubilized viral membrane antigens from EBV-superinfected Raji cells

In an attempt to qualitatively identify the membrane antigen (MA) complex induced by Epstein-Barr virus (EBV) infection of lymphoblastoid cells, superinfected Raji cells were surface labelled with 125I by the lactoperoxidase method and solubilized with Triton X-100, then the 125I-labelled membrane proteins were precipitated by sera containing high antibody titers to MA. Analysis of these immune precipitates on sodium dodecyl sulfate polyacrylamide gel eletrophoresis identified four major EBV-specific membrane proteins with molecular weights (mol. wt) of 280,000, 250,000, 170,000 and 90,000. Sera from patients with Burkitt's lymphoma (BL), nasopharyngeal carcinoma (NPC) and infectious mononucleosis (IM) and from EBV-infected disease-free individuals showed differential patterns of reactivity to these antigens with some sera only recognizing three or less of the antigens. The results from invesigations with these sera also indicated that these major proteins were not related to EBV-induced viral capsid antigens (VCA) or the virus-associated early antigen (EA) complexes as defined by immunofluorescence. Metabolic labelling of EBV-infected Raji cells with [14C]glucosamine, followed by Triton X-100 solubilization and radioimmune precipitation, identified the 280,000, 250,000 and 90,000 components as glycoproteins. The lactoperoxidase-labelled 170,000 molecular weight component was not significantly glycosylated and, therefore, could not be categorized as a glycoprotein on the basis of this study. In addition, a glycoprotein with a mol. wt of 130,000 was identified by this approach which also appeared to be specified by EBV. The results from these investigations, therefore, indicated that the EBV-induced MA complex was composed of four major glycoproteins and one nonglycosylated high mol. wt protein.

Studies on Epstein-Barr virus-related antigens. I. Indirect single radial immunodiffusion as a useful method for detection and assay of soluble antigen

A useful method for the detection and assay of Epstein-Barr virus (EBV)-related soluble antigen has been developed by the application of the indirect single radial immunodiffusion technique which is frequently used for quantitative measurements of immunoglobulins and other soluble proteins. When the extracts of EBV-determined nuclear antigen (EBNA)-positive non-producer cells (Raji and NC-37) were applied to agar plates containing seropositive human serum, followed by overlay with anti-human IgG serum, ring-shaped precipitates with high specificity were clearly evident. The size of such precipitin rings was proportional to the amount of the antigen. This method is simple and applicable for a quantitative assay of a particular EBV-related soluble antigen and antibody and the sensitivity is equivalent to that seen with the complement fixation test.

Studies of Epstein-Barr virus (ebv)-associated nuclear antigen. I. assay in human lymphoblastoid cell lines by direct and indirect determination of 125I-IgG binding

A quantitative assay for EBNA in human lymphoblastiod cell lines has been developed. The assay employs EBNA-positive and -negative 125-I-IgG preparations as reagents and can be used in a direct or indirect manner. EBNA specificity has been demonstrated in a number of ways. The antigenic relationship between EBNA present in Raji cells and in a number of other human lymphoblastiod cell lines of diverse origins and between the cell-associated antigen present in FT Raji cells and that present in isolated Raji nuclei has been studied. The possibility of carrying out blocking titrations for anti-EBNA determination has been demonstrated and the effect of glutaraldehyde and formaldehyde upon antigenic activity in FT Raji cells has been studied.