Humoral immunity in myasthenia gravis: Biochemical characterization of acquired antireceptor antibodies and clinical correlations

Abstract

The titer and characteristics of antiacetylcholine receptor antibody (AChR-Ab) were investigated in 184 patients with myasthenia gravis. Mean AChR-Ab titers of each clinical grade increased with the severity of the disease. AChR-Ab was always of an IgG class. IgM (5 of 92) and IgA (2 of 48) class AChR-Ab were detected, but only concurrently with IgG and in low concentrations. IgG subclass 3 was not prominent. In 3 patients with AChR-Ab titers in the normal range, blockade of bungarotoxin binding to receptor could still be demonstrated. AChR-Ab from 6 patients was heterogeneous in affinity for receptor, reactivity from human ocular and gastrocnemius muscle, and blockade ot toxin binding. AChR-Ab was oligoclonal in 4 of 6 patients, as shown by concurrent production of AChR-Ab IgG of both kappa and lambda types. Amniotic fluid and fetal cord serum did not interfere with antibody-receptor interaction. Variation in the pattern of weakness among patients was a function of both the heterogeneity of AChR antibodies and the antigenic uniqueness of receptor complexes from different human muscles.

Myasthenia gravis: Reactivation of clinical disease and of automimmune factors after discontinuation of long‐term azathioprine

“…Moreover, in all but 1 patient the clinical relapse was preceded by a rise of the antibody titer. This further supports the notion that the intraindividual correlation among patients between the serum autoantibody concentration and the clinical severity of the disease is usually good [ S , 28,[30][31][32]. After reinstitution of immunosuppressive treatment, the elevated titers declined slowly, approaching the pretreatment levels.…”

Presence and Pathogenic Relevance of Antibodies to Clustered Acetylcholine Receptor in Ocular and Generalized Myasthenia Gravis

“…[21][22][23][24] Herein, in a large group of patients with MG, including SNMG, studied at the time of SFEMG, we found a correlation between jitter values and AChR-Ab titers and clustered AChR-Abs in patients with SNMG. The correlation of complement-fixing capacity with neuromuscular jitter was greater, again supporting the likely importance of the complement system in the pathogenesis of AChR-Ab-positive MG.…”

Correlating extent of neuromuscular instability with acetylcholine receptor antibodies

“…Both laboratory tests are highly sensitive in the diagnosis of MG, 10,11,18,21,22,24 but previous studies have not shown a clear relationship between the degree of abnormality and the clinical severity, presentation, or prognosis of myasthenia. Strong correlations between the mean AChR antibody titers and the clinical severity of disease in groups of MG patients have been reported previously, 14,23 but the absolute AChR antibody titer is often of limited value in predicting the nature of disease progression or its prognosis. Nevertheless, clinical improvement after plasma exchange may be associated with a fall in titer in individual patients.…”