Tumour necrosis factor alpha concentrations in the peritoneal fluid of infertile women with minimal or mild endometriosis are lower in patients with red lesions only than in patients without red lesions.

Tumour necrosis factor alpha (TNFalpha) of peritoneal fluid is believed to have important pro-inflammatory and angiogenic activities in the complex mechanisms of development of peritoneal endometriotic lesions. We have evaluated the concentrations of TNFalpha and macrophages in peritoneal fluid of infertile women with minimal or mild endometriosis and related them to the presence of peritoneal red lesions alone (red lesions only group; n = 11) or their absence (non-red lesions group; n = 36). A group of 39 infertile normo-ovulatory patients with normal pelvic anatomy was used as controls. TNFalpha concentrations did not differ between controls and either group of patients. Patients with red lesions only had significantly lower concentrations of TNFalpha in peritoneal fluid (P < 0.05) and had a higher proportion of samples with undetectable concentrations (P < 0.05) than patients without red lesions. The significant difference in TNFalpha concentrations was present when comparing the groups of patients in the proliferative phase but not in the secretory phase. Macrophage concentrations were not different in the groups. Our findings are compatible with an impairment of macrophage function and therefore lend support to the theory that an inappropriate immunological response of the peritoneal environment to regurgitated endometrium may play a part in the initial phases of endometriotic implants.