Activation of Peripheral Blood Neutrophils and Lymphocytes by Human Procathepsin D and Insulin-like Growth Factor II

Cathepsin D, a lysosomal aspartic proteinase, is well known to be overexpressed and secreted in the form of its zymogen by many types of human breast cancer tissues. In the cell lines derived from these tissues, cathepsin D functions as an autocrine mitogen, and it was suggested that its secretion might pose some physiological functions. Recently we have identified the presence of procathepsin D in human breast milk and similar findings were reported for bovine milk which imply also some physiological function. Thus, we have tested the influence of procathepsin D and insulin-like growth factor II on the expression of CD11a, CD11b, FcRI, CD62L, and HLA-DR surface determinants on neutrophils and lymphocytes. We have used procathepsin D purified from the secretions of breast cancer cell line ZR-75-1 and commercially available IGF II. Our results showed that both studied factors significantly influence the expression of tested surface molecules.