IMMUNOLOCALIZATION OF BCL-2 IN THE HUMAN CORPUS-LUTEUM

The mechanisms of luteal regression and rescue in women are unknown bu t forms of programmed cell death may be involved. The proto-oncogene b cl-2 is an important inhibitor of apoptosis but has not previously bee n described in the human corpus luteum. Immunohistochemical localizati on of bcl-2 protein was investigated in human corpora lutea obtained f rom women undergoing surgery during endocrine monitored menstrual cycl es as well as from women who had been treated with human chorionic gon adotrophin (HCG) to prolong the luteal phase, Bcl-2 was found to be lo calized in granulosa-lutein, theca-lutein (as identified by co-localiz ation of P450(17 alpha-hydroxylase)) and the endothelial cells around some blood vessels. Immunoblotting demonstrated the presence of a sing le band of similar to MW 26 kDa. There was no apparent change in eithe r the intensity of immunostaining or the histological localization dur ing the normal luteal phase or following treatment with human chorioni c gonadotrophin. The product of the proto-oncogene bcl-2 is present in the human corpus luteum, It is unlikely that bcl-2 expression alone i s responsible for prolongation of the lifespan of the corpus luteum in early pregnancy although it is possible that the action of the bcl-2 gene present is modified by changes in other members of the bcl-2 fami ly.