A comparative immunofluorescent study of fixed decalcified tissue and frozen non-decalcified tissue from the guinea pig cochlea.

The immunofluorescence test (IF) is an important diagnostic laboratory tool for detecting immune-mediated sensorineural hearing loss (SNHL). The results of applying the IF to ethanol-fixed, paraffin-embedded, decalcified sections of guinea pig cochlea as compared with frozen non-decalcified preparations are presented. Sera from ten patients with SNHL were tested in addition to antibody-positive and negative human serum controls. Despite fixation and prolonged decalcification, deparaffinized cochlear sections showed a strong positive reaction with most of the positive serum controls. Anti-endothelial antibodies were detected in the serum of one patient and anti-nuclear antibodies in another. The fine cochlear structure was clearly delineated. However, the decalcified specimens failed to react with one serum model, which revealed a positive fluorescence when incubated with the frozen non-decalcified cochlear preparations. These latter findings denote possible leaching of the antigenic material from the sections. This study further shows that frozen nondecalcified cochlear tissue is a reliable tissue source for the interpretation of the results obtained with IF.