Antigen processing and presentation capability of EBV-positive T and NK tumor lines. (A) Flow cytometric analysis of cell surface HLA class I. Representative data from 2 lines (SNT 16 and SNK 6, black shading) compared with a LCL (dark gray shading) is shown. (B) Western blot of whole cell lysates probed with antibodies to transporter associated with antigen processing (TAP) 1 and 2 and total cellular class I heavy chains (HC 10) in NK- and T-cell lines, shown relative to levels in a LCL. Calregulin serves as the loading control. (C) EBV antigen expression in NK- and T-cell lines. Western blot of whole cell lysates of EBV-positive NK- and T-cell tumor lines probed with antibodies to EBNA 1, EBNA 2, LMP1, and LMP2A compared with a LCL and an EBV-negative NK line (NKL). Note the different molecular weight of EBNA 1 in the different lines is attributable to the variable size of the Gly-Ala repeat domains. (D) Schematic indicating the exon structure of the LMP2 gene and splicing patterns of conventional LMP2A and LMP2B transcripts, across the TR region of the genome. Each transcript contains a unique 5′ first exon (1A for LMP2A, shaded gray and 1B for LMP2B, shaded white). (E) Real-time PCR for LMP2A and LMP2B mRNA. Gray and white shaded bars represent quantities of LMP2A and LM2B transcripts, respectively, relative to a LCL. Error bars indicate SDs from the mean.