Oncostatin M, interleukin 2, interleukin 6 and interleukin 8 in breast cyst fluid

Women with breast cysts lined by apocrine epithelium (intracystic Na/K < 3) may have a higher risk of developing breast cancer than those whose breast cysts are lined by "flattened" epithelium (intracystic Na/K < 3). In this study, the concentrations of the cytokines, oncostatin M (OSM), interleukin 2 (IL-2), interleukin 6 (IL-6) and interleukin 8 (IL-8) were measured in breast cyst fluid, OSM, IL-2 and IL-6 having been shown to have growth-inhibitory actions on tumour cells. All cytokines were measured by "sandwich" enzyme immunoassays. IL-2 was not detectable in breast cyst fluid. OSM, IL-6 and IL-8 concentrations were significantly higher in the high-electrolyte-ratio group. Although significant positive correlations were found between OSM and IL-6, OSM and IL-8, OSM and Na/K, IL-6 and IL-8, IL-6 and Na/K and IL-8 and Na/K when all samples were analysed together, analysis of the correlations between these analytes in each subgroup separately suggests that the control of production of these cytokines or the mechanism of entry into cyst fluid is likely to be different for the 2 cyst types. The significantly higher intracystic concentrations of OSM and IL-6 in the high-electrolyte-ratio group may partly explain the lower risk of breast cancer in this group of women.