a method for producing an antibody to a polypeptide, antibody produced therein, antibody or antibody fragment that binds to a polypeptide, methods for reducing or inhibiting il-20 induced proliferation or differentiation of hematopoietic cells and hematopoietic cell progenitors, to reduce il-20 induced inflammation, to suppress an inflammatory response in an inflamed mammal, to treat a mammal afflicted with an inflammatory disease, to treat a pathological condition in a patient associated with il-20 activity