Binding affinities of anti-acetylcholine receptor autoantibodies in myasthenia gravis
Antibodies directed against acetylcholine (ACh) receptors are present in the sera of nearly 90% of patients with myasthenia gravis (MG), and are involved in the pathogenesis of this autoimmune disease. However, the antibody titers measured by the standard radioimmunoassay correspond poorly with the clinical severity of the disease. To determine whether this disparity could be accounted for by differences in the binding affinities of anti-ACh receptor antibodies in different patients, we have measured the binding affinities of these autoantibodies in 15 sera from MG patients. The affinity constants (K/sub o/), as determined by Scatchard analysis, were all in the range of 10/sup 10/ M/sup -1/, comparable to the highest values reported in immunized animals. The affinity constants were truly representative of the population of autoantibodies detected by the radioimmunoassay, as shown by the remarkable linearity of the Scatchard plots (r/sup 2/>0.90) and the close correlation between the antibody titers determined by extrapolation of the Scatchard plots and by saturation analysis (r = 0.99; p < 0.001). There was only a 6-fold variation in affinity constants measured in this series of patients despite widely differing antibody titers and severity of the disease. Factors other than the titer and affinity of anti-ACh receptor antibodies may correlate better with the clinical manifestations of MG.
- Research Organization:
- The Johns Hopkins Univ. of Medicine, Baltimore, MD
- OSTI ID:
- 5639239
- Journal Information:
- J. Immunol.; (United States), Vol. 128:1
- Country of Publication:
- United States
- Language:
- English
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ANTIGEN-ANTIBODY REACTIONS
BINDING ENERGY
IMMUNITY
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LABELLED COMPOUNDS
MUSCLES
PATHOGENESIS
RECEPTORS
AMINES
AMMONIUM COMPOUNDS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
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ISOTOPES
NEUROREGULATORS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PARASYMPATHOMIMETICS
QUATERNARY COMPOUNDS
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TRACER TECHNIQUES
550601* - Medicine- Unsealed Radionuclides in Diagnostics