It is generally accepted that the current scoring system for endometriosis has little correlation with clinical symptoms such as pain, and therefore we may deduce that either endometriosis does not cause pain, or that the current scoring system does not indicate the biological activity of the disease. Pain may occur because the presence of endometriosis produces an intraperitoneal inflammatory response, and several studies have shown that the cytokine content of peritoneal fluid differs between women with and without endometriosis. We studied the relationship between tumour necrosis factor alpha (TNF alpha), platelet-derived growth factor (PDGF), interleukin (IL)-6, IL-4 and TNF (alpha and beta) activity in peritoneal fluid and the clinical history of pain and infertility. TNF alpha concentrations were increased in peritoneal fluid of women with endometriosis and of infertile women; PDGF concentrations were increased in peritoneal fluid of parous women; IL-6 was increased in peritoneal fluid of women with adhesions; IL-4 was absent from peritoneal fluid. PDGF and IL-6 concentrations were cycle related, with the highest amounts in the menstrual and proliferative phases respectively. We failed to demonstrate any association between concentrations of cytokines in vitro and pain symptoms or severity of endometriosis.

The present study investigates the specificity of anti-endometrial antibodies present in serum of women with endometriosis. A two colour indirect immuno-histochemical method was used, so that the antigenic reactivity of endogenous immunoglobulins was blocked and specific anti-endometrial antibodies were readily distinguishable. Serum was collected from women with endometriosis, before and after 6 months of treatment, and from women without the disease. The reactivity of serum with uterine and ectopic endometrium from women with and without the disease was studied. The frequency of anti-endometrial antibodies in the serum of women with endometriosis was higher (P < 0.001) than in control sera. Most antibodies specifically reacted with glands in ectopic and uterine endometrium. Antibody reactivity was strongest with endometrium from control women, compared with uterine and ectopic endometrium from women with endometriosis (P < 0.01). A proportion of sera containing anti-endometrial antibodies also reacted with vascular endothelium. Binding was strongest to vessels in uterine and ectopic endometrium from women with endometriosis compared to endometrium from women without the disease (P < 0.01). The presence of anti-endometrial antibodies was associated with infertility.

Uterine endometrium contains numerous bone marrow-derived cells. The spectrum of cell types is different from that of any other tissue, and the differences in endometrium from women with endometriosis may reflect a different endometrial phenotype in these women. The cell types of bone marrow origin found in ectopic endometrium may indicate the degree of differentiation of the tissue. It was found that, in normal endometrium, the CD45+ cell population comprised T cells, macrophages, CD56+ large granular lymphocytes, some CD16+ cells and a few B cells. Changes in these cell populations during the menstrual cycle were similar in endometrium from both controls and patients with endometriosis, and resembled that reported previously by others. In ectopic endometrium, the frequency of CD45+ cells remained within the same range as that of uterine endometrium but without any obvious pattern of change during the menstrual cycle. CD56+ large granular lymphocytes, an immune cell type characteristic of uterine endometrium, were also found in ectopic endometrium. Our results indicate that ectopic endometrium, as well as comprising both glandular and stromal cells, contains bone marrow-derived cell populations similar to those of uterine endometrium. This suggests that the same processes of cell migration and/or differentiation occur in ectopic and uterine endometrium.

No abstract