Functional analysis of an Epstein-Barr virus-nontransformed human B cell line

A human B cell line, IW.2, was established from the culture of peripheral blood lymphocytes of a patient with chronic lymphocytic leukemia. IW.2 was shown to express IgM, B1 (CD20), and 12 (a major histocompatibility complex class II antigen) molecules on the cell membrane by analysis of flow microfluorometry (FMF) as well as a receptor for the third component of complement (C3R), but not to express an Epstein-Barr virus nuclear antigen. The cell growth of IW.2 was markedly inhibited when treated with either B cell stimulatory factor from phytohemagglutinin-conditioned medium or 12-O-tetradecanoylphorbol-13-acetate. Interestingly, IW.2 cells were capable of generating a significant amount of both IgM and IgG at the same time when stimulated with these reagents, followed by a decrease in the expression of IgM, B1, and I2 molecules on the cell membrane as well as C3R. The results suggest that IW.2 cells may be a model for the study of the maturation of human B cells.