We generated recombinant antibodies (rAbs) from over-represented IgG sequences expressed by single plasma cells from multiple sclerosis (MS) cerebrospinal fluid (CSF). Panning of a phage-displayed random peptide library with the rAbs revealed several specific peptide sequences. Inhibition assays confirmed specific binding of the peptides to the antigen-binding site of the antibody. The native IgG of MS CSF from which the recombinant antibody was cloned also recognized these peptides. Our data demonstrate that MS rAb reflects the specificity of IgG in the CSF. Thus, the epitopes/mimotopes identified by MS rAb may provide clues to disease-relevant antigens.