Evans blue as counterstain in the demonstration of muscle antibodies by immunofluorescence in myasthenia gravis.

The binding of muscle antibodies to skeletal muscle was studied by immunofluorescence techniques. The non-specific fluorescence was not significantly reduced by absorption of the conjugate by tissue powder but was abolished by counterstaining with a 0.1% Evans blue. Possible explanations for this effect are discussed. By this method, immunofluorescence may become more useful in the demonstration of muscle antibodies.