Local immune state in the women with miscarriage

Functional state of immunity provides maintenance of immunological tolerance for allogeneic fetus, and high level of local protection against antigenic stimulation. Increased functional activity of phagocytic cells at systemic and local levels may cause impairment of complete fetoplacental complex, thus leading to abortion. The purpose of our study was to assess the state of local immunity in women with pregnancy loss.

The study involved 174 women in their reproductive age. The first group consisted of 65 patients (37.4%) with a diagnosis of miscarriage, the history of < 2 abortions over the period from conception to the 20th week of gestation. The second group included 37 patients (21.2%) with documented recurrent pregnancy loss, with a history of > 3 miscarriages. The control group consisted of 72 conditionally healthy women (41.4%) who had 2 or more term pregnancies with the same partner, without a history of obstetric and gynecological complications. Their mean age was 36±6 years old. Total number and viability of leukocytes, the indices of functional neutrophil activity, their functional reserve and neutrophil stimulation index were determined in cervical mucosal samples over the first phase of the menstrual cycle.

In the first phase of menstrual cycle, the women with miscarriage and recurrent pregnancy loss exhibited a statistically significant increase of phagocytosis by the neutrophils from cervical mucus as compared to the group of conditionally healthy women. Intensity of neutrophil phagocytosis in cervical mucus reached higher values in the women with recurrent pregnancy loss more often, compared to the control group. Evaluation of the functional reserve of cervical mucus neutrophils in the subjects with recurrent pregnancy loss and miscarriage showed a trend towards statistically significant differences: this parameter was higher in the patients than in control group. The ability of cervical mucosal neutrophils to produce reactive oxygen species (both spontaneous and induced) did not show statistically significant differences between the patients and controls.

Hence, we have observed aberrant functional activity of neutrophilic granulocytes from cervical mucosa in the groups of women with 2 or more abortions, without changing ability of the cells to produce reactive oxygen species. This finding may be explained by prevalence of oxygen-independent mechanisms of intracellular killing, thus suggesting a role of neutrophils for impaired balance of immunological tolerance in pregnant women at the local level.