IL-12: Monoclonal antibodies specific for the 40-kDa subunit block receptor binding and biologic activity on activated human lymphoblasts

Journal Article · Sun Sep 01 00:00:00 EDT 1991 · Journal of Immunology; (United States)

OSTI ID:5017924

Chizzonite, R; Truitt, T; Podlaski, F J; Wolitzky, A G; Quinn, P M; Nunes, P; Stern, A S; Gately, M K ^[1]

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1. Department of Molecular Genetics, Roche Research Center, Hoffmann-La Roche, Inc., Nutley, NJ (United States)

IL-12, formerly known as cytotoxic lymphocyte maturation factor, is a cytokine that stimulates proliferation of PHA-activated human peripheral blood lymphoblasts and synergizes with low concentrations of IL-2 in the induction of lymphokine-activated killer cells. IL-12 is a 75-kDa heterodimer composed of disulfide-bonded 40-kDa and 35-kDa subunits. mAb prepared against a partially purified preparation of natural IL-12 have been characterized by (1) immunoprecipitation of 125I-labeled IL-12, (2) immunodepletion of IL-12 bioactivity, (3) Western blotting of IL-12, (4) inhibition of (125I)IL-12 binding to its cellular receptor, and (5) neutralization of IL-12 bioactivity. Twenty antibodies immunoprecipitate 125I-labeled IL-12 and immunodeplete IL-12 bioactivity as assessed in the T cell proliferation and lymphokine-activated killer cell induction assays. Western blot analysis demonstrated that each antibody binds to the 75-kDa heterodimer and to the 40-kDa subunit. An IL-12R-binding assay identified 12 individual antibodies that inhibited the binding of (125I)IL-12 to its cellular receptor. Two inhibitory antibodies, 4A1 and 7B2, were tested in the neutralization assay and found to block IL-12 bioactivity whereas one noninhibitory antibody, 8E3, was shown not to neutralize IL-12 bioactivity. Antibodies 4A1 and 8E3 can simultaneously bind to the 75-kDa heterodimer demonstrating that inhibitory and noninhibitory epitopes are spatially distinct on the 40-kDa protein. The ability of antibodies specific for the 40-kDa subunit of IL-12 to block receptor binding of (125I)IL-12 and to neutralize IL-12 bioactivity suggests that localized determinants on the 40-kDa subunit may be necessary for binding to the IL-12 cellular receptor.

• OSTI ID: 5017924
• Journal Information: Journal of Immunology; (United States), Vol. 147:5; ISSN 0022-1767
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
GROWTH FACTORS
RECEPTORS
LYMPHOCYTES
CELL PROLIFERATION
MONOCLONAL ANTIBODIES
SPECIFICITY
BIOCHEMICAL REACTION KINETICS
IODINE 125
MAN
RATS
TRACER TECHNIQUES
ANIMAL CELLS
ANIMALS
ANTIBODIES
BETA DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LEUKOCYTES
MAMMALS
MATERIALS
MEMBRANE PROTEINS
MITOGENS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PRIMATES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
SOMATIC CELLS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques