Cytokine expression in human endometrium throughout the menstrual cycle.

Recent evidence suggests that diverse endometrial functions may be regulated by cytokines. In this report, the presence of protein and mRNA of cytokines were studied in human endometrium throughout the menstrual cycle. The presence of the interleukin-1 (IL-1) alpha, interleukin-1 (IL-1) beta, interleukin receptor antagonist (IRAP), interleukin-6 (IL-6) and transforming growth factor (TGF)-alpha proteins were demonstrated by immunohistochemical staining. The IL-1 alpha and TGF-alpha proteins were strongly expressed and IL-1 beta protein was weakly expressed in all the cells in the stroma as well as epithelial cells. IRAP was markedly expressed in the cells with morphological features of macrophages scattered in the stroma, and the expression of IL-6 protein was predominant in the endometrial epithelium. Diffuse cytoplasmic expression of IL-1 alpha in endometrial epithelium during the proliferative phase contrasted markedly with its enhanced luminal expression during the secretory phase of the menstrual cycle. In addition, the presence of the mRNA of these cytokines in endometrium was established throughout the entire menstrual cycle by reverse transcription-polymerase chain reaction (RT-PCR). Abundant expression of cytokines in human endometrium emphasizes the significant roles that cytokines play in cell-cell interactions and in regulating endometrial functions.