Analysis, by coimmunoprecipitation assays, of the assembly of BCR components in CLL patients. (A) Analysis of molecules associated with μ or CD79a. B cells from patients 1 and 8 were lysed in digitonin and the resulting cell extract was immunoprecipitated with Abs against CD79a (left panel) or μ (right panel) chains. Immunoprecipitates (IP) were analyzed with anti-μ, anti-CD79a, or anti-CD79b mAbs. (B) Study of the glycosylation status of the molecules associated and unassociated with the CD79a chain. B cells from patients 1 and 8 were lysed in digitonin and the resulting cell extract was immunoprecipitated with anti-CD79a mAb. IP or supernatants from the IP were treated in the presence (+) or the absence (-)of Endo-H and analyzed using anti-μ (top row of blots) or anti-CD79b (bottom row) Abs. μ# indicates the deglycosylated form of μ chains after Endo-H treatment. ^*Nonspecific band observed with the anti-CD79b probe.