[Purification and specificity control of labelled antibodies (author's transl)].

A review is given about causes of unspecific binding and the possibility of its prevention. Unspecific binding can be caused by: binding of proteins and glycoproteins on cells or tissues by non-covalent links, undesirable antigen-antibody-reactions, non-immune affinity reactions, changes of the charge of antibodies depending on the labelling procedure. A method for fractionation of labelled antibodies by using precipitation with protamine sulphate is described.