Beta amyloid precursor protein and patterns of HIV p24 immunohistochemistry in different brain areas of AIDS patients

Objectives: To evaluate the correlation between immunohistochemical positiv e patterns (globular and filamentous structures) of beta -amyloid precursor protein (beta -APP), used as a marker of axonal damage, and the different distribution of HIV p24 antigens, in three different brain areas of AIDS pa tients. Methods: Eighteen AIDS patients with HIV-related brain lesions were include d in the study. Forty-nine sections from basal ganglia, frontal cortex and hippocampus were selected. After microwave oven pre-treatment, the sections were incubated with anti-HIV p24 and anti-beta -APP monoclonal antibodies; the reactions were developed with peroxidase/3,3'diaminobenzidine. The pos itivity was graded by semi-quantitative scores. Double immunohistochemical staining was used to Evaluate the co-localization of the antigens. Results: HIV p24 immunohistochemistry was positive in 44 of 49 sections (89 %), with a prevalence of interstitial positive cells and positive microglia l nodules in 27 and 13 sections respectively. beta -APP-positive structures were demonstrated in 23 of 44 sections (52%) with HIV-related lesions, and were absent from the five sections without viral expression. Globular and filamentous lesions were observed in 21 of 23 sections and 10 of 23 lesions respectively. Moreover, a high grade of globular type lesion was related t o an elevated presence of diffuse interstitial HIV p24-positive cells in ba sal ganglia; double immunohistochemical reactions demonstrated the co-local ization of beta -APP globules and HIV p24 antigens. Conclusions: The data obtained confirm the coexpression of beta -APP and vi ral antigens in particular areas of the brain with HIV-related lesions; the re is a strict correlation between beta -APP globules (indicating chronic c erebral damage) and the interstitial pattern oi HIV p24 immunohistochemistr y. (C) 2001 Lippincott Williams & Wilkins.