Generation of a panel of human FCRL1-5-specific mAbs. FCRL1-5 mAbs were screened for cross-reactivity with BW5147 cells retrovirally transduced with plasmids expressing individual HA-tagged FCRLs. Cells were stained with the indicated biotin-coupled mouse IgG isotype FCRL mAbs (histogram, black line) or isotype matched controls (histogram, gray shade) followed by SA-PE, and analyzed by flow cytometry. Positive control staining was performed with the 12CA5 (anti-HA) mAb. FCRL1-5 mAbs also did not react with FCRL6 transductants (not shown).