Autoreactive membrane associated proteins were identified in a subset of eight CLL patients. (A-D) Immunoblot analysis of autoreactive membrane associated proteins demonstrated immunoreactive bands (delineated by red boxes) (A,C). The identified autoreactive bands were subsequently excised from the coomassie-stained twin gels (B,D) and analyzed by mass spectroscopy to obtain preliminary protein identifications (Table 1). (E) ELISA analysis of LCP1-specific IgG in 33 previously untreated CLL patients and 6 healthy donor controls. (F) ELISA was used to compare autoimmune IgG responsiveness to LCP1 relative to the known vaccine antigen, tetanus toxin (Tet). All CLL patients assayed by ELISA had not received any previous intravenous immunoglobulin therapy. Statistical analysis was performed by Student t test; Error bars indicate standard error of the mean (P = .0004).