Antibodies to blood group antigens mimic pemphigus staining patterns: a useful reminder

Pemphigus is a clinically important autoimmune skin disease characterised by intercellular substance antibodies, detected by indirect immunofluorescence on monkey oesphagus tissue. It has been observed that anti-A and anti-B blood group antibodies can produce staining patterns similar to that seen in pemphigus, yet this potential problem is not well recognised. We have demonstrated false positive pemphigus staining with blood group O sera and describe features by fluorescence and confocal microscopy, which may be useful in distinguishing true from false positive pemphigus staining.