CD40 and B-cell non-Hodgkin lymphoma: In order to visualize these interactions in cells with endogenous expression levels, the CD40-positive and Fas-positive B-cell lymphoma cell line BJAB, with or without expression of TRAILR2, was used.24 Immunocytochemistry using antibodies against the ectodomains of CD40, Fas and TRAILR2 showed colocalization at the cell surface between CD40 and Fas in TRAILR2-negative BJAB cells.