Attachment of Antinuclear Antibodies to Nasopharyngeal Carcinoma or Other Cells During Preparation of Biopsy Imprints<xref ref-type="fn" rid="FN2">2</xref>

The presence of Epstein-Barr virus (EBV) genomes in nasopharyngeal and other carcinomas or Burkitt's and other B-cell lymphomas can be established by the demonstration of viral nucleic acid sequences in DNA extracts from biopsy specimens, the detection of EBV-associated nuclear antigen (EBNA) in biopsy imprints, and the inhibition of leukocyte migration by tumor extracts. Of these techniques, the detection of EBNA-positive tumor cells can be performed most readily in the laboratory. This report shows that a patient's antibodies to nuclear antigens can gain access to cell nuclei during the preparation of imprints. If the antibodies are directed against EBNA, nuclear immunofluorescence is elicited solely in the tumor cells when only complement (C') and fluorescein-labeled antibodies to C' are applied to the imprints without prior exposure to anti-EBNA-positive sera. If nonspecific antinuclear antibodies (ANA) are involved, the nuclear immunofluorescence seen in the EBNA-specific and control assays is not limited to the tumor cells but extends to any normal cells that may be present in the imprints. Furthermore, nuclear fluorescence is elicited when solely an anti-human IgG conjugate is applied because ANA is measurable by indirect immunofluorescence, whereas detection of EBNA requires augmentation of the antigen-antibody complexes by C', which differentiates further between EBNA-specific and nonspecific staining. Attachment of antibodies to nuclei can be avoided by minimizing the deposit of blood during imprint preparation and by rapid drying of the imprints. Similar results are obtained experimentally when smears of lymphoblasts are made in the presence of anti-EBNA or ANA.