Cells from peripheral tissues that exhibit high APP expression are characterized by their high membrane fusion activity.

The amyloid precursor protein of Alzheimer's disease (APP) is ubiquitously expressed suggesting a general function throughout the organism. We have used APP-specific antibodies to investigate the expression and localization of APP in different tissues from rat (testis, ovary, liver, kidney, spleen, pancreas, salivary gland). Immunohistochemistry demonstrated that APP is highly expressed in Sertoli cells, follicle cells, secretory cells, podocytes and macrophages. Features common to these cells include their high membrane turnover and their functional characteristics of endocytic and phagocytic retrieval and exocytosis. This suggests APP may participate in interactions of cells of the mononuclear phagocytic system, and function in relation to tissue maintenance and repair.