Bound immunoglobulins of classes M,A, and G studied in the thymus of patients with myasthenia gravis

Deposits of granular material containing immunoglobulins (Ig) of the M, A, and G classes, were found by direct immunofluorescence in the thymus of patients with myasthenia. Treatment of sections of the thymus of myasthenic patients with unlabeled preparations against individual classes of human Ig inhibits the reaction of the granular material with homologous labeled preparations. Disappearance of fluorescence of the deposits also was observed in sections treated with glycine-HCl buffer, pH 2.8. These results suggest that the granular material consists of immune complexes in which IgM, IgA, and IgG act as antibodies and components of the thymus tissues as the antigen. The presence of bound Ig in the thymus is evidence that in myasthenia an autoimmune process directed against the tissues of this organ is involved.Laboratory of Streptococcal Infections, N. F. Gamaleya Institute of Epidemiology and Microbiology. Professorial Surgical Department, I. M. Sechenov First Moscow Medical Institute. Laboratory of Clinical Pathophysiology, Institute of General and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR M. I. Kuzin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 6, pp. 709–712, June, 1978.