Comparison of immune assays for the detection of anti-HSP70 antibodies in patients with idiopathic sensorineural hearing loss

BACKGROUND: Detection of anti-heat-shock protein 70 (HSP70) IgG response by Western blot (WB) is of clinical utility in a subset of patients with idiopathic sensorineural hearing loss (SNHL) due to autoimmunity. METHODS: To validate an immune assay for the detection of anti-HSP70 antibody responses in the clinical laboratory, we employed a commercial anti-human HSP70 IgG/A/M ELISA and developed an anti-HSP70 IgG WB test. Using sera from 81 patients with idiopathic SNHL and 100 healthy controls, we assessed each assay performance with results from another diagnostic laboratory that utilizes a WB test. RESULTS: Our results showed a significant lack of agreement between either WB assay and the anti-human HSP70 IgG/A/M ELISA for antibody-positive samples. Comparison of WB assays revealed a significant level of agreement (89.7%) for all samples tested. CONCLUSIONS: Our data suggest that the antigenic targets in WB and ELISA immunoassays differ and demonstrate that the anti-HSP70 IgG WB test is reproducible within and between clinical laboratories. Thus, in the absence of disease-specific markers, the anti-HSP70 IgG WB assay could be of use to detect patients with idiopathic SNHL who might benefit from steroid treatment.