IL-4 increases expression of CD79B and the “mature” glycoform of sIgM. CLL samples were treated with IL-4 for 24 hours or left untreated as a control (NA). (A) CD79A and CD79B mRNA expression was quantified by quantitative polymerase chain reaction (n = 9). β2M was used as the housekeeping gene, and relative expression values were normalized to the untreated cells. (B) Representative sample expressing CD79A and CD79B protein was analyzed by immunoblotting and (C) summarized for CD79B from immunoblotting following Image J quantitation (n = 26). BCL2 expression was analyzed as a loading control. (D) The fold change of CD79B expression between the NA control and IL-4 treated cells was quantified and represented for U-CLL and M-CLL (n = 19). (E) CLL cells were treated with IL-4 and assessed by immunoblotting for total levels of μ-chain (whole cell protein; WCL) or surface protein (SP) μ-chain. EndoH was used to digest the mannosylated µ-chain of IgM (**), whereas the fully glycosylated form (*) was confirmed by resistance to EndoH cleavage. (F) WCL extraction or SP was analyzed by immunoblotting from CLL samples treated in the presence or absence of IL-4. The protein band intensity of mature and immature IgM was quantified using Image J (n = 12). Statistical significance was determined by paired Student t test or Wilcoxon matched pairs signed rank test.