Analysis of μ chain glycoform expression in normal B cells after treatment with anti-μ. (A) Surface proteins were purified from normal B cells of 3 healthy donors treated in vitro with anti-μ (+) or isotype control (−) for 24 hours; μ chains were analyzed by immunoblotting. Data are representative of a total of 5 experiments. (B) Surface proteins from another healthy donor were purified and treated as in panel A for 24 hours. Proteins were then exposed to EndoH or PNGase or left untreated and analyzed by immunoblotting. The immature form (◁) and the mature form (◀) of μ chain are indicated in panels A and B.