Epstein-Barr virus DNA and latent gene products in Ki-1 (CD30)-positive anaplastic large cell lymphomas.

Epstein-Barr virus (EBV)-specific DNA sequences were detected by polymerase chain reaction analysis in 15 of 47 (32%) DNA extracts prepared from CD30-positive (Ki-1 antigen-positive) anaplastic large cell (ALC) lymphomas. EBV-encoded RNA (EBER) transcripts could be detected by in situ hybridization in the tumor cells of 9 of 11 EBV DNA-positive cases. Twenty-eight cases were examined by immunohistology on cryostat sections for the presence of the EBV-encoded latent membrane protein (LMP), the nuclear antigen 2 (EBNA2), the BZLF1 transactivator protein, and the late viral glycoprotein gp350/250. A distinct LMP-specific membrane and cytoplasmic staining was detected exclusively in lymphoma cells of five cases (18%); two of these cases additionally expressed EBNA2. BZLF1 protein and gp350/250 immunoreactivity was absent in all instances. All LMP-positive cases contained EBV DNA and EBER sequences. The pattern of EBV latent protein expression in ALC lymphomas showed heterogeneity with respect to EBNA2 expression: LMP-positive/EBNA2-negative cases displayed a pattern previously described for undifferentiated nasopharyngeal carcinomas and Hodgkin's disease, whereas LMP-positive and EBNA2-positive cases showed parallels to lymphoblastoid cell lines. Because the LMP gene has transforming potential, our findings support the concept of a pathoetiologic role for EBV in a proportion of CD30-positive ALC lymphomas.