Immunohistochemical study of the proliferation index, oestrogen receptors and progesterone receptors A and B in leiomyomata and normal myometrium during the menstrual cycle and under gonadotrophin-releasing hormone agonist therapy

The cell proliferation-associated antigen Ki 67 and the immunohistochemical content of oestrogen receptors (ER), progesterone receptors AB (PRAB) and progesterone receptors B (PRB) were evaluated in leiomyomata and adjacent m yometrium during the menstrual cycle and in leiomyomata under gonadotrophin -releasing hormone agonist (GnRHa) therapy. The proliferative status of mus cular cells was measured by evaluating the percentage of nuclei staining po sitive for Ki 67 (proliferation index), Quantitative analysis (QH-score) wa s carried out using advanced stereographic computer technology to investiga te ER, PRAB and PRE. Leiomyoma and myometrial biopsies were taken from 30 p atients undergoing hysterectomy or myomectomy because of symptomatic leiomy omata (subgroup I). Leiomyoma biopsies were taken from 10 patients sufferin g from symptomatic submucosal leiomyomata, after 2 month GnRH therapy (subg roup II). During the secretory phase, the proliferation index (Ki 67) was f ound to be higher in leiomyomata than in myometrium, but the difference was not significant, Oestrogen receptor content was significantly higher in le iomyomata than in myometrium only during the proliferative phase of the cyc le. PRAB and PRE content were found to be higher in leiomyomata than in adj acent myometrium with a statistically significant dominance of PRAB over PR E. Under GnRHa therapy, a dramatic decrease was observed in PRAB and B cont ent as well as Ki 67 but ER content remained comparable with the results ob tained during the menstrual cycle. The results suggest that leiomyomata may be under the influence of progesterone which may play a major role in thei r growth.