Immuno-electron microscopical investigations with a new tracer: peroxidase-labeled protein A: application for detection of pemphigus and bullous pemphigoid antibodies.

Peroxidase-labeled Protein A, stable immunoenzyme tracer of high reactivity and comparatively low molecular weight, has been applied in immuno-electron microscopy for detection of bound IgG-type pemphigus and bullous pemphigoid antibodies. Comparing Protein A-peroxidase with peroxidase-labeled immunoglobulins, we obtained similar morphological results in corresponding incubation techniques, but lower nonspecific adsorption of Protein A-peroxidase complexes in tissues. The Protein A-peroxidase molecules showed good tissue penetration abilities. Our rapid one-step incubation procedure led to enhanced preservation of tissue fine structures, without the need of prior tissue fixation. It seems that Protein A-peroxidase is able to replace peroxidase-labeled anti-IgG for immuno-electron microscopical purposes.