Immunolocalization of bcl-2 in the human corpus luteum

The mechanisms of luteal regression and rescue in women areunknown but forms of programmed cell death may be involved.The proto-oncogene bcl-2 is an important inhibitor of apoptosisbut has not previously been described in the human corpus luteum.Immunohistochemical localization of bcl-2 protein was investigatedin human corpora lutea obtained from women undergoing surgeryduring endocrine monitored menstrual cycles as well as fromwomen who had been treated with human chorionic gonadotrophin(HCG) to prolong the luteal phase. Bcl-2 was found to be localizedin granulosa-lutein, theca-lutein (as identified by co-localizationof P450_{17-hydroxylase}) and the endothelial cells around someblood vessels. Immunoblotting demonstrated the presence of asingle band of MW 26 kDa. There was no apparent change in eitherthe intensity of immunostaining or the histological localizationduring the normal luteal phase or following treatment with humanchorionic gonadotrophin. The product of the proto-oncogene bcl-2is present in the human corpus luteum. It is unlikely that bcl-2expression alone is responsible for prolongation of the lifespanof the corpus luteum in early pregnancy although it is possiblethat the action of the bcl-2 gene present is modified by changesin other members of the bcl-2 family. apoptosis/bcl-2/corpus luteum/granulosa/17-hydroxylase