HSP90AA1 and Alzheimer disease: Using home-made indirect ELISA assay, we found for the first time that serum levels of anti-Hsp90 IgE were significantly elevated (p < 0.0001) in AD patients (n = 29) as compared to age- and gender-matched healthy controls (n = 70), whereas levels of anti-Hsp90 IgG, IgM, or IgA were similar between both groups (Fig. 2a).