FIG 4.

Polyreactivity and specificity of natural IgM. (A) Binding of IgM to DNP-BSA determined by ELISA. BALB/c IgM was purified from serum as previously described (8, 9). DNP-BSA-binding and DNP-BSA-nonbinding pools of IgM were purified from BALB/c IgM by affinity chromatography. Monoclonal antibody 2E4 is a polyreactive IgM that can bind to a variety of antigens (21). (B) Binding of IgM to AdCMV-Luc by ELISA. (C) Binding of IgM to AdHVR7 by ELISA. A monoclonal IgM against HBV (H21F8-1; ATCC CRL-8018) showed poor reactivity to AdHVR7. Similar results were obtained on AdCMV-Luc-coated plates (not shown). (D) Influence of IgM transfer on liver transduction in Rag-1^−/− mice. Mice were injected i.v. with PBS or IgM (500 μg) 2 h before i.v. injection with 4 × 10¹¹ vp/kg of AdHVR7. Liver transduction was assayed at 48 h. Groups that do not share the same letter (a, b, and so on) are significantly different from each other (n = 4 or 5 per group, P ≤ 0.05; ANOVA and Holm-Sidak post hoc test). Error bars represent SD. All antibodies were of BALB/c genetic origin.