Novel compositions derived from antigen-binding sites of immunoglobulins having affinity for IL-31 are provided. The compositions exhibit immunological binding properties of antibody molecules capable of binding specifically to a human IL-31. CDR regions derived from same or different immunoglobulin moieties are provided. Also provided are single chain polypeptides wherein VH and VL domains are attached. The sFv molecules can include ancillary polypeptide moieties which can be bioactive, or which provide a site of attachment for other useful moieties. The compositions are useful in specific binding assays, affinity purification schemes, drug or toxin targeting, imaging, and genetic or immunological therapeutics for inflammatory diseases. The invention thus provides novel polypeptides, the DNAs encoding those polypeptides, expression cassettes comprising those DNAs, and methods of inducing the production of the polypeptides. The invention further provides the amino acid sequences of the variable regions of the monoclonal antibodies and use of these monoclonal antibody or antibody fragment in conjunction with an human IgG4 Fc molecule.