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), Journal Name: J. Immunol.; (United States) Vol. 128:1; ISSN JOIMA
- Country of Publication:
- United States
- Language:
- English
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62 RADIOLOGY AND NUCLEAR MEDICINE
ACETYLCHOLINE
AMINES
AMMONIUM COMPOUNDS
ANTIBODIES
ANTIGEN-ANTIBODY REACTIONS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BINDING ENERGY
DAYS LIVING RADIOISOTOPES
DIAGNOSIS
DISEASES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ENERGY
ESTERS
IMMUNITY
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
MUSCLES
NEUROREGULATORS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PARASYMPATHOMIMETICS
PATHOGENESIS
QUATERNARY COMPOUNDS
RADIOASSAY
RADIOIMMUNOASSAY
RADIOISOTOPES
RECEPTORS
TRACER TECHNIQUES