Bradykinin antibodies: new developments.

Because all antibodies to bradykinin described to date more or less cross-react with larger and smaller bradykinin derivatives, the aim of the present study was the induction of a specific antibody against bradykinin. A bradykinin derivative, containing a Cys residue at position 6 instead of Ser, was linked to BSA by using a new heterobifunctional cross-linking reagent, the N-maleimido-6-aminocaproyl ester of 1-hydroxy-2-nitro-4-benzenesulfonic acid (mal-sac-HNSA). The Cys6-bradykinin derivative conjugated via the SH group to BSA was used to elicit bradykinin-specific antibodies in rabbits. After the fifth booster injection, the cross-reactivity of this antiserum with kallidin is 4 X 10(-3) when compared with bradykinin. The cross-reactivity of the de-Arg1-bradykinin derivative was 2 X 10(-4), indicating that the antibody requires the free N-terminus. The cross-reactivity of bradykinin and de-Arg9-bradykinin was nearly identical. However, de-Arg9-de-Phe8-bradykinin has a binding of 6 X 10(-3). From these data, it can be concluded that due to the ring-like structure of bradykinin, the coupling of bradykinin in the center of the molecule will elicit an antiserum that needs both the free N-terminal as well as the C-terminal phenylalanine and arginine residues for antibody recognition.