SERUM FROM NORMAL ELDERLY INDIVIDUALS CONTAINS ANTIBASEMENT MEMBRANE ZONE ANTIBODIES

Background: Bullous pemphigoid is an autoimmune bullous disease with c irculating anti-basement membrane zone antibodies, and it commonly aff ects elderly individuals; however, the reasons for the late onset of t he disease are unclear. Design: The anti-basement membrane zone antibo dies in serum samples from normal elderly subjects were compared with those in serum samples from normal young subjects. Participants: Serum samples from 32 elderly and 28 young normal individuals and 10 patien ts with bullous pemphigoid were used. Interventions: Indirect immunofl uorescence against guinea pig esophagus or human salt-split epidermis and immunoblotting against human and guinea pig epidermis were perform ed. Results: Serum samples from young individuals were devoid of anti- basement membrane zone antibodies against guinea pig esophagus and hum an salt-split epidermis. Among 32 serum samples from elderly patients, 6 cases (19%) were positive for anti-basement membrane zone antibody for guinea pig esophagus, and in those the titers were 10 in 3 cases a nd 40, 80, and 320 in the others. One case was positive against human split epidermis at a titer of 10. An immunoblotting analysis showed th at the antigenicity of the 230-kd and 180-kd bullous pemphigoid antige n from guinea pig epidermal extract was similar to that of human epide rmal extract; however, the molecular weight was slightly different. Th e 4 cases of elderly serum that recognized guinea pig esophagus baseme nt membrane zone showed positivity with the 230-kd peptide in the guin ea pig epidermal extract; however, they were negative with the human e pidermal extracts. Direct immunofluorescence observation of these case s showed that deposition of IgG or C3 was not present in cryostat sect ions from flexor arm surfaces. Conclusions: The serum samples from eld erly subjects possessed a relatively high incidence of anti-basement m embrane zone antibodies detectable with guinea pig esophagus as substr ate. This observation of a specific immune defect in elderly individua ls might explain why they are more susceptible to developing bullous p emphigoid.