Figure 5.

VH3 and modified SpA reactivity. (A) VH3-positive antibodies from mature naive and IgM⁺ memory B cells were tested for reactivity with mSpA by ELISA. Horizontal line shows cut-off OD₄₀₅ for positive reactivity as determined by comparison to ED38 (dotted line, VH1-69 and references 2, 43), the negative control antibody mGO53 (green line, VH4-39, and reference 2) and the low positive control antibody eiJB40 (red line, VH3-23 and reference 2). The frequency of mSpA-reactive clones and the number of antibodies tested are indicated below the graphs. (B) The frequency of mSpA-reactive antibodies for individual VH3-family members is shown for mature naive (black bars) and IgM⁺ memory (gray bars) B cell antibodies with the number of antibodies tested indicated. (C) mSpA-binding as measured by ELISA for mutated IgM⁺ memory B cell antibodies (n = 22) and their unmutated counterparts after reversion of IgM⁺ memory B cells antibody IgH and IgL chain genes into their germline forms by PCR.