Introduction: In spite of increasing number of immune cells in the endometrium during the decidualization, the integrity of endometrial tissue in each menstrual cycle is maintained by adaptive changes in expression of several factors that regulate activity of immune cells and concomitant hormonal alterations during the menstrual cycle. This regulatory function of endometrium is also related to resistance to apoptosis, in which metallothionein (MT) may play a role.
Materials and methods: Study group included 26 women with spontaneous abortion and 18 patients with tubal ectopic pregnancy. Control group included 17 women whose endometrial tissue samples were taken during the normal secretory cycle phase. Expression of metallothionein (MT), CD56 and CD69 were assessed in tissue samples by immunohistochemistry.
Results: The number of CD56-positive cells was significantly higher in women with ruptured than unruptured ectopics. MT expression was higher in tubal mucosa distant from the implantation site in ruptured compared to unruptured ectopics. It was found also to be significantly lower than in decidua taken from women with spontaneous abortion. CD69 expression was similar in women with spontaneous abortion as well as patients with ruptured ectopics compared to the control group. On the other hand, CD69 expression in unruptured ectopics was significantly lower than in women with spontaneous abortion and the control group.
Conclusion: The concentration of immune cells and increase of their activity in tubal mucosa, with insufficient protection against immune-mediated apoptosis assessed by MT expression, might result in tubal rupture during ectopic pregnancy.