Assay of GCDFP-15 by ELISA: an available method for in vitro studies of functional differentiation in human breast cancer.

An enzyme-linked immunosorbent assay (ELISA) was applied to a light protein, isolated from human breast cyst fluid (BCF) termed "gross cystic disease fluid protein - 15 Kda" (GCDFP-15), a potential differentiation marker in in vitro human breast cancer studies. The detection limits of this procedure, performed in microtiter plates, were 0.5 to 250 ng/well corresponding to 10 ng/ml to 5 micrograms/ml of sample or antigen solution. Possible cross-reaction with various antigens, especially those found in culture media, were investigated. The correlation coefficient between enzymoassay and radioimmunoassay was 0.978. The results showed that quantification of GCDFP-15 by ELISA is a specific and highly sensitive method. This procedure may be of interest in in vitro studies on the functional differentiation of breast cancer cells.