Figure 3. Over-representation of IGHV4-34 among SLE ASC clonal expansions.

(a) Plots showing size distribution of individual clonotypes for 17 samples with large IGHV4-34 clones depicted as red bins. For each subject, clonality is depicted for both CD138⁻ ASC (“−”), and CD138⁺ ASC (“+”). Within each bar, lineages are ordered by size from bottom to top and delineated by horizontal lines. Selected VH-genes (where the normalized lineage size is greater than 0.1% of total sequences) are shown in colors. Bar graphs above the lineage plots show the percentage of sequences in the largest 20% of clones that were IGHV4-34, which was significantly higher in SLE (p < 0.01, Wilcoxon rank sum test). (b) Elispot analysis of antigen-specific ASC. Frequencies of 9G4, Flu, and Tetanus responses are shown as % of total IgG spots. Boxes are 25^th to 75^th percentiles, lines in boxes are medians, whiskers show extent of non-outlier data (outliers are 1.5 times the interquartile range beyond 25^th or 75^th percentiles). Note different scales for 9G4 and Flu, Tetanus. (c) Autoantibody frequency (as determined by Elispot), in SLE patients with large increases of ASC (>10% of CD38⁺⁺CD27⁺⁺ of IgD⁻CD19⁺ cells). Left horizontal bars: frequency of CD138⁻ and CD138⁺ ASC in individual SLE patients (n=16); right horizontal bars: corresponding percentages of autoantibody specificity out of total IgG ASC.