Dendritic cells (DCs) are specialized antigen presenting cells that are highly involved in the stimulation and modulation of the immune response within mucosal surfaces, including the female reproductive tract. DCs have been poorly characterized in the non-pregnant endometrium.

Hysterectomy specimens were obtained from premenopausal women (n = 49) with histoloigically normal endometrium. Endometrial sections were stained immunohistochemically using antibodies for monoclonal mouse anti-human CD1a and CD83, two markers which are specific for populations of immature and mature DCs, respectively.

There was a significantly higher density of endometrial CD1a+ DCs than CD83+ DCs throughout the menstrual cycle (P < 0.001). The density of CD1a+ and CD83+ DCs did not vary between the fundus and isthmus of the uterus. There was a significant increase in the density of CD1a+ DCs, but not CD83+ DCs, in the basal layer of the endometrium through the phases of the menstrual cycle. The density of CD83+ was significantly greater in the basal layer compared with the functional layer during both the proliferative (P = 0.004) and secretory phases (P = 0.001), whereas for CD1a+ DCs, the greater density in the basal layer was only observed in the secretory phase (P < 0.001).

The highly coordinated cyclical changes in DC populations during the normal menstrual cycle reported in this study may be important for local regulatory mechanisms relevant to menstruation and implantation; alterations in this normal profile may contribute to the development of disturbances of function, fertility and even benign gynaecological disease.