Correlation of colitis histopathology score (0_60) with serum anti_Fla-X and anti-CBir1. Twenty-three mdr1a–/– mice, ranging in age from 6 to 13 weeks, were randomly chosen for assignment of quantitative histopathology scores. Serum anti-flagellin from these mice was quantified by ELISA. Colitis scores of 0_2 represent no disease; 3_15, mild disease, 16_35, moderate disease, and more than 35, severe disease (22). Similar results were obtained for both recombinant flagellins: Fla-X (left panel) and CBir1 (right panel).