Phage peptides recognize persistent antibodies in corresponding serum. Consecutive pairs of MS sera and CSF (S1, C1, S2, C2) were examined by IEF-immunoblotting (see Fig. 5 legend). In two of three patients, phage peptides recognized persistent oligoclonal IgG bands in the paired sera, although all three CSF showed persistent IgG reactivity (see Fig. 2). Positive controls were sera and CSF probed with AP-anti-human IgG. Experiments were repeated twice. A, patient 1 (02-24); B, patient 2 (04-3); C, patient 3 (05-4). Data represent at least three independent experiments.