Temporal artery biopsies. Correlation of light microscopy and immunofluorescence microscopy.

Immunopathologic studies are done routinely on biopsy specimens from tissues affected by many autoimmune diseases. To evaluate the role of direct immunofluorescence microscopy (DIFM) in identifying temporal arteritis, the authors reviewed all temporal artery biopsies done over a 30-month period (100 consecutive biopsies). The DIFM, using antibodies to IgG, IgM, IgA, complement, and fibrinogen, had a diagnostic sensitivity rate of 93% and a specificity rate of 87% compared with light microscopy. In biopsy specimens showing arteritis by light microscopy, IgG was demonstrated by DIFM in 85% of cases, IgM in 69%, and IgA in 15%. In one patient, a DIFM staining pattern highly suspicious of temporal arteritis identified a patient with features of clinical temporal arteritis despite negative findings by light microscopy. The demonstration of immunoglobulin by DIFM supports the possible role of humoral immunity in the pathogenesis of temporal arteritis.