Rat bladder epithelium: A sensitive substrate for indirect immunofluorescence of bullous pemphigoid

Serological diagnosis of bullous pemphigoid is based on immunoblotting or i ndirect immunofluorescence on normal human salt-split skin. These methods a re expensive or time-consuming and not available as a routine test in all l aboratories. We used rat bladder epithelium as substrate for indirect immun ofluorescence and compared it with other substrates and with immunoblotting , Twenty-nine bullous pemphigoid sera were studied on rat bladder epitheliu m, monkey oesophagus, salt-split skin and with immunoblotting on human kera tinocyte cultures. Indirect immunofluorescence on rat bladder epithelium pr oved to be more sensitive (72%) than on monkey oesophagus alone (45%) and l ess sensitive than on salt-split skin (97%). Rat bladder epithelium, when t ested on 41 sera of a control group, showed a very high specificity: 2/41 ( 95%), In combination with immunoblotting on keratinocyte extracts, indirect immunofluorescence on rat bladder epithelium allowed 93% of sera to be rec ognized, a value close to the salt-split skin alone, Rat bladder epithelium appears to be a more sensitive substrate than monkey oesophagus for the di agnosis of bullous pemphigoid and, although less specific, it is easier and faster than using salt-split skin, which remains indispensable to distingu ish bullous pemphigoid from epidermolysis bullosa acquisita.