Western blot and immunoprecipitation demonstrating significant levels of cCD20 in the plasma of patients with CLL.

(Panel A) Western blot showing detectable CD20 protein in plasma from patients with CLL. The plasma CD20 is similar in molecular weight to CD20 detected in cell lysates from BJAB cell line (BJ) and cells from a patient with CLL (C). As expected, no CD20 is detectable in lysate from the HL60 cell line (HL). Plasma from a healthy control individual (N) shows lower levels of CD20. Immunoprecipitation products from BJAB (B) and HL60 (H) cell lysates are also shown. Precipitation from beads and antibody without plasma or cell lysate is also shown as a negative control (NC). The molecular weight marker (M) is shown. One microliter of plasma is used in lanes that contain plasma. The levels of cCD20 detected in the plasma by ELISA are shown on the bottom. (Panel B) Coomassie blue-stained gel showing immunoprecipitation of CD20 from plasma of patients with CLL. The CD20 from cell lysates from BJAB (B) and CLL (C) are shown as positive control and from HL60 (H) as a negative control. Equal amounts of plasma (33 μL) from each sample were denatured before immunoprecipitation (abbreviation as in Panel A).