We established a new lymphoma cell line, designated CTB-1, from pericardial effusion of a patient with diffuse large B-cell lymphoma. This cell line showing vigorous growth ability has undergone 260 passages over a period of 34 months in suspension culture, and is heterotransplantable to nude mice. The cultured cells were positive for CD10, CD19, CD20, CD21, HLA-DR, and surface IgG kappa, and negative for T cell antigens. Chromosomal analysis revealed a t(14;22)(q32;q11) that is consistent with original lymphoma cells. CTB-1 cells show the high cell surface expression level of Fas antigen/APO-1. However, ligation of Fas antigen with anti-Fas monoclonal antibody (clone CH-11) did not induce apoptosis of CTB-1 cells. This suggests that Fas itself or the downstream signaling pathways of Fas may be impaired in this cell line. This new cell line may provide a useful in vitro system to study the biology and pathogenesis of B-cell lymphoma which is independent of Fas-mediated apoptosis.