Reactivity and specificity of rFab and nFab derived from CLL cells from 12 patients tested for all identified CLL antigens. (A) rFabs obtained by BCR cloning and expression and (B) CLL-derived nFabs obtained by papain digestion show identical specificity in the ELISA using the recombinant CLL antigens as antigenic coats. (C) Reactivity and specificity of nFab derived from CLL cells from 47 patients tested for previously identified CLL antigens. On the x-axis, all 51 patients are shown (patients 29, 33, and 34 failed during Fab preparation; patient 7 does not qualify); the antigens tested are listed on the y-axis and included (from front to back: BSA, acetylated BSA, LDL, oxidized LDL (oxLDL), Streptococcus pneumoniae, calreticulin, cofilin, vimentin, myosin heavy chain 2A (MYH2A), U266 cells before and after induction of apoptosis with methotrexate, and CMV-derived pUL32 protein. Only 3 reactivities were detected: oxLDL was recognized by BCRs from patients 6 and 8 and MYH2A was recognized by patient 38.