Monoclonal antibodies to human interferon-gamma. II: Antibodies with neutralizing activity.

Two types of hybridomas secreting monoclonal antibodies (MAB) with neutralizing activity against human interferon-r (HuIFN-r) were obtained by somatic cell hybridization between mouse myeloma P3UI cells and spleen cells from BALB/c mice immunized with purified recombinant HuIFN-r and a conjugate of a synthetic amino-terminal peptide (residues 4-21) of HuIFN-r and bovine thyroglobulin. One of these MAB recognized the amino-terminal region (residues 4-21) of HuIFN-r, and the other recognized some region in the internal part (residues 22-130) of the molecule. These results suggest that another region, in addition to the amino-terminal region, contributed to the biological activity of rHuIFN-r. A combination of one of these MAB and a previously described MAB directed to the carboxyl-terminal region (residues 131-146) of HuIFN-r enables a quantitative and sensitive assay method of biologically active rHuIFN-r.