Blood and cell infiltrate neutrophilic leucocytes As inflammation markers in chronic endometritis: A prospective non-randomised controlled trial

Background. Inflammation declares itself with the presence of cellular tissue infiltrate, which composition reflects the inflammation type. Chronic inflammation is predominated by mononuclear cell infiltration with a certain amount of neutrophils, which role and significance are not fully understood to date.

Objectives. Assessment of the infiltrated neutrophil count at various chronic endometritis severity and its dependency on the functional and metabolic activity in neutrophilic leucocytes in peripheral blood.

Methods. This prospective non-randomised controlled trial estimated the CD45⁺ leucocyte and activated CD16b⁺ neutrophil counts in inflammation infiltrate using immunohistochemistry protocols. Cell counts per section 1 mm² were measured with computer morphometry. The content of and NADPH oxidase activity in activated neutrophilic leucocytes in venous blood were estimated with a nitroblue tetrazolium reduction test.

Results. The study included 40 women with a history of chronic endometritis (CE) divided in two cohorts by endometrial biopsy data, with inactive (n = 25) and active CE (n = 15). A control cohort comprised 20 women with no signs of CE. The inactive CE cohort had higher counts of CD45⁺ leucocytes and activated CD16b⁺ neutrophils in infiltrate compared to control. Higher content of activated neutrophilic leucocytes with higher NADPH oxidase activity were found in peripheral blood. Morphological exacerbation markers of EC were associated with sharper peaks of CD45⁺ and CD16b⁺ cell counts in infiltrate and an elevated functional metabolic activity in circulating neutrophilic leucocytes. A strong direct correlation was revealed between blood activated neutrophil and endometrial CD16b⁺ neutrophil counts, as well as NADPH oxidase activity in blood neutrophils and infiltrate CD16b⁺ cell counts.

Conclusion. Even minor morphological markers of exacerbated endometrial inflammation are accompanied by the elevated infiltrate counts of both total CD45⁺ leucocytes and activated CD16b⁺ neutrophils. The functional metabolic activity of peripheral blood neutrophilic leucocytes is interlinked with the inflammatory infiltrate cell composition and reflects severity of chronic endometrial inflammation.

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