Abstract
The purpose of this study was to test the hypothesis that Breast Cyst Fluid (BCF) is a secretion from the "pink" epithelial cells found to line such cysts. A series of BC fluids specially collected over a period of 18 months from a local hospital clinic, as well as routinely sent samples, were investigated for their cell content, proteins, and various chemical parameters compared with milk and serum. Histological and cytological material was examined by light and electron microscopy with various stains, and by immunohistochemical techniques using an antiserum raised against whole BCF. The aspirates could be divided into two groups based on cell content and cellulose acetate electrophoresis of the fluid. These methods correlated well. The lack of immunoglobulins in one group was examined and possible reasons for this suggested. The chemical content was found to be very variable; for all parameters a large range was found, and for most, levels were close to those of serum. The exceptions are urate, cholesterol and potassium which tended to be high. Cholesterol often reached enormous levels and was found to be mainly present in a particulate fraction of the whole fluid. The particulate fraction was separated by density gradient centifugation and analysed for cholesterol, protein, and various membrane marker enzymes, which suggested a possible origin from cell membranes. The antiserum to BCF was found to contain antibodies to 2 BCF-specific proteins after absorption to remove antibodies to serum and milk proteins. The specific proteins were found by immunohistochemistry to locate in the Golgi complex of the 'pink' cell, and also in apocrine glands from axillary skin. Whilst the process of secretion was never observed, electron microscopy showed the 'pink' cell to have secretory characteristics.