Protein concentrations in fluid from gross cystic disease of the breast.

Wide variations in the concentrations of IgA, IgG, lactoferrin, lysozyme and albumin were found in 96 cyst fluids obtained from 75 patients with gross cystic disease of the breast. Sedimentation coefficient determination were performed on 19 of the cyst fluids with the highest IgA concentrations in an attempt to discover the basis for the wide variation and two types of cyst fluids were found: cyst fluids that resembled external secretions such as colostrum of milk with the IgA wholly or predominantly in the 11S (secretory) form, and low concentrations of IgG and albumin, and cyst fluids that resembled serum with the IgA wholly or predominantly in the 7S (serum) form, and high concentrations of IgG and albumin. Some cyst fluids contained low concentrations of all proteins measured, and no relationship was observed between the concentrations of the proteins studied, and age, parity or menstrual status.