Differentiation and Ig-allele switch in cell line WEHI-231.

Because of its susceptibility to apoptosis upon Ag receptor cross-linking and lack of IgD expression, cells of the mouse cell line WEHI-231 have been classified as immature B cells. In this study we show that early freezings of the WEHI-231 line express IgD but not CD93, which classifies the cells as more similar to mature B cells. Another, later line obviously has differentiated in culture and has all the hallmarks of activated B cells. But despite activation-induced cytidine deaminase expression, there is no switch in isotype; instead we found switching from one mu allele to the other. As a consequence of these findings, we now view the apoptosis studies in the WEHI-231 line to reflect properties of mature and activated B lymphocytes, respectively.