Effect of prolactin on class II HLA antigen expression by MCF7 cell line

Effects of prolactin on Class II HLA Ag expression have been identified for the first time in a human breast cancer cell line maintained in long-term tissue culture (MCF7) and were reported in this work as follows. Quantification methods for assaying Class II HLA Ag expression modulated by prolactin were established. Class II HLA Ags were internally labelled with [35S] methionine, extracted with Nonidet P-40, immunoprecipitated specifically with anti-Class II HLA MoAbs, isolated on protein A-Sepharose and quantified by chromatofocusing. For low doses of prolactin added to a final concentration (0.015 to 0.350 micrograms/ml culture medium), no change in Class II HLA Ags expressed by MCF7 cells was observed, when compared with controls, the percent of Class II HLA Ags assayed by chromatofocusing was then 4.03 +/- 0.57. For high doses of prolactin added to the final concentration (1.50 micrograms to 3.00 micrograms/ml medium), the percent of Class II HLA Ags increased to 6.05 +/- 0.72. When prolactin was added to the culture medium of MCF7 human breast cancer cell line, increased Class II HLA Ag expression by membrane cells was noted. Prolactin induction of Class II HLA Ag expression by human breast cancer cell lines should prove very useful to study the biology of prolactin in the tumorogenesis of the human breast.