Impaired central B-cell tolerance in RA and T1D humanized mice. Single CD19⁺CD21^loCD10⁺IgM^hiCD27^– new emigrant/transitional B cells were sorted from PB of 1 HC and 1 RA donor, and from the spleen of 1 HC, 1 RA, and 1 T1D humanized mouse. Expression cloning was carried out as described³¹  and antibodies from new emigrant/transitional B-cell clones were tested by enzyme-linked immunosorbent assay for reactivity against (A) double-stranded DNA (dsDNA), insulin, and lipopolysaccharide (LPS) or for (B) anti human epithelial type 2 (HEp-2) cell reactivity. Dotted lines show monoclonal polyreactive antinuclear antibody control (ED38⁺) and solid lines show binding for each cloned recombinant antibody. Horizontal lines define cutoff optical density at 405 nm (OD₄₀₅) for positive reactivity. For each sample, the frequency of polyreactive (filled area) and nonpolyreactive (open area) clones is summarized in pie charts, with the total number of clones tested indicated in the centers.