Monoclonal Antibodies Against Human Haptoglobin

Abstract

Three monoclonal antibodies: 2.36.71.41, 7.60.66.55, and 18.4.40. 80 to human haptoglobin 2–1 were produced, purified and characterized. The affinity constants ranged within 0.3–2.4 x 108 M^-1. The monoclonal antibodies 7.60.66.55 and 18.4.40.80 reacted with β subunit of haptoglobin, showed similar epitope affinities and epitope densities on main haptoglobin types. However, the epitope on the haptoglobin molecule for the monoclonal antibody 18.4.40.80 occupied somewhat more surface than that for the antibody 7.60.66.55. The monoclonal antibody 2.36.71.41 was able to bind both α and β chains of haptoglobin. In ELISA affinity reactions this antibody achieved with haptoglobin 2–2 the plateau phase at absorbance values 15% higher than with haptoglobin 2–1, and 60% higher than with haptoglobin 1–1. End-point titration of the monoclonal antibody 2.36.71.41 against three haptoglobin types showed differences in titer, indicating distinct epitope densities.