Interleukin-1 receptor antagonist expression in epithelial cells of human endometrium.

OBJECTIVE

To examine the expression of interleukin-1 (IL-1) and IL-1 receptor antagonist (IL-1ra) in the human endometrium in the follicular and luteal phases.

METHODS

The concentrations of IL-1alpha and IL-1beta in the culture supernatants of endometrial cells were determined by enzyme-linked immunosorbent assay. Transcription of the IL-1ra gene in the endometrium was investigated by reverse polymerase chain reaction (PCR). Human endometrium was immunohistochemically stained using a monoclonal antibody specific to IL-1ra.

RESULTS

The concentrations of IL-1alpha and IL-1beta in the culture supernatants were 11 and 55 pg/ml, respectively, in the follicular phase, and 10 and 40 pg/ml, respectively, in the luteal phase. The concentration of IL-1ra was 465 pg/ml in the follicular phase and 1710 pg/ml in the luteal phase. Densitometric analysis of the reverse PCR products showed that the expression of IL-1ra mRNA was increased in endometrial cells in the luteal phase. Immunohistochemical staining revealed that epithelial cells were the main source of IL-1ra in human endometrium.

CONCLUSIONS

Human endometrial cells produce IL-1 (mainly IL-1beta) and IL-1ra. The level of IL-1ra production in human endometrial epithelial cells was greater in the luteal phase than in the follicular phase due to the increased transcription of the IL-1ra gene.