Detection of antigens determined by the epstein barr virus (EBV) in human lymphoblastoid cell culture lines by elution of specific radioiodine labeled antibody

Antigens determined by EBV in lymphoblastoid cell lines derived from BL and NPC biopsies have been defined and quantitated by elution of specific radioiodine labeled antibodies (RIE) from live target cells. By treating an antigen negative cell line with 5-iododeoxyuridine (IUDR) or superinfecting it with EBV in the presence of cytosine arabinoside (Ara C), early antigen was induced whereas viral capsid antigen (VCA) did not appear. These preparations were exposed to labeled human EA and VCA reactive antibody. Subsequently, the bound fraction was eluted at pH 2.8. There was a good correlation between the peak of elutable radio-activity and the percentage of EA positive cells by immunofluorescence. It was concluded that this reaction measured EA. Labeled Ig with EA and VCA specificity was allowed to compete with unlabeled MA (membrane antigen) and VCA positive, but EA negative, serum for reactive sites on target cells expressing all three antigens. Successful antibody competition indicated that the reactants were competing for VCA. EBV superinfection in the presence of Ara C induced EA and MA but no VCA in an originally antigen negative line. The binding and subsequent elution of a labeled MA+, EA-, VCA+ Ig from these cells demonstrated anti-MA activity. Sequential elution experiments, performed after different numbers of washes, demonstrated that measurable MA activity was lessened after each wash. The specificity of the antibody binding and elution was demonstrated by successful antibody competition with unlabeled sera containing the corresponding antibodies, but not by EBV negative human serum (NHS). Labeled Ig from NHS did not bind to the positive target cells in a paired radioiodine labeled antibody test (PRILAT). Labeled EBV-reactive Ig bound selectively to the antigen positive "producer" lines but not to antigen negative "nonproducer" cell lines. Antigen induction by graded doses of superinfecting EBV was quantitated by the RIE technique in one of the originally antigen negative cell lines. There was good agreement between the level of antigen induction as judged by immunofluorescence and the amount of eluted radiolabeled Ig.