Does Myasthenic Serum Bind to the Neuromuscular Junction?

ionSince the original demonstration of a muscle-binding, complement-fixing factor (MGF) in the serum of some patients with myasthenia gravis,' there has been further study of this phenomenon.I t has been investigated in reference to organ specificity,' disease specificity,' frequency' concurrance with antithymus epithelial cell reactivity? and noncomplement-fixing anticardiac muscle r e a ~t i v i t y , ' .~ techniques of detectionBl o and affinity for muscle extracts.*' '' However, identification of the binding sites of M G F at the ultrastructural level and the pathophysiological significance of this factor remain to be determined.This report describes investigation of possible reactivity between the neuromuscular junction (nmj) and MGF.Tissue containing nmjs was studied first by the indirect immunofluorescent technique and subsequently by histochemical demonstration of cholinesterase which allowed identification of nmjs.Fluorescing structures which resembled nmjs during the immunofluorescent study were identified as debris, clumped erythrocytes, fragmented tissue and crystalline particles after the cholinesterase staining, and they differentiated from nmjs on the basis of morphologic properties and/or the absence of cholinesterase activity.