We report a new and apparently unique human lymphoma cell line termed Deglis. The line was established from a polymorphic centroblastic lymphoma. The cell line and its source carry a dual B-cell and T-cell phenotype and Epstein-Barr virus (EBV) genomes. Simultaneous expression of B-cell (CD19+, CD20+, CD23+, CD37+) and T-cell (CD2+, CD3+/-, CD7+, CD43+) antigens, activation antigens (CD30+, CDw70+) as well as CD68+, a macrophage-associated antigen, was observed on the cell line and its source. Genotypic studies of the cell line showed dual gene rearrangements. JH (on both primary tumor and the cell line) and C kappa were rearranged without expression of cytoplasmic or surface immunoglobulins. T-cell receptor-alpha (TCR-alpha) and TCR-beta genes were rearranged, but TCR-delta and TCR-gamma genes were in germline configuration. Apparently, functional transcripts of TCR-alpha and truncated transcripts for TCR-beta and TCR-delta were observed. EBV- encoded proteins (LMP and EBNA2) were expressed by the parent tumor and the cell line. Southern blot analysis showed the same clonal EBV genomes in the primary tumor and the cell line. Karyotypic analysis of the cell line showed several chromosomal abnormalities but normal chromosomal number. The characteristics of this cell line suggest that neoplastic transformation has occurred in a precursor cell broadly committed to lymphoid lineage. Further studies on this cell line may help resolve some issues in the physiopathology of lymphoid tumors.