The Ig HC repertoire was single-cell PCR amplified from splenic follicular (A) and MZ (B) B-cells from B6 (151 FO and 166 MZ HC sequences, all clonally independent, amplified from 2 mice) and B6.Sle1z (201 FO and 159 MZ HC sequences, all clonally independent, amplified from 7 mice), and examined for the frequencies of ANA-associated HC sequence motifs “A”, “B”, and “C”. Annotations are as detailed in Fig. 2. Indicated P-values pertain to Chi-square test or Fisher's exact test comparisons of B6.Sle1z HC sequence versus B6 control sequences (1, P < 0.05).