Assessment of leukocyte subsets in the blood of patients with endometriosis: importance of controlling for confounders such as smoking, age, and oral contraceptives

Objective: Previous studies suggest that several leukocyte populations are altered in the peritoneal cavity of patients with endometriosis. The present study is designed to determine whether any immune abnormalities could also be found in other sites such as the peripheral blood.Design: Case-controlled study including 175 patients with endometriosis and 131 disease-free controls.Materials/Methods: Blood mononuclear cells were isolated from peripheral blood by centrifugation through Ficoll-Hypaque. The proportion of CD45+ mononuclear cells expressing surface markers for T, B lymphocytes, monocytes or NK cells or expressing activation molecules was compared by flow cytometry analysis in patients with endometriosis and in normal controls. Several parameters such as age, personal habits, menstrual characteristics and clinical manifestations of endometriosis were taken into account in this study.Results: Age, parity, smoking habit, previous use of oral contraceptives and history of acute infection within the last month influenced significantly the proportion of most leukocyte subsets in the blood and appeared to be important confounders in the present study. When these parameters were carefully controlled, the proportion of B lymphocytes was shown to be significantly decreased in patients with endometriosis compared to controls. On the other hand, the proportion of blood monocytes expressing CD13 and CD44 molecules was shown to be increased in patients with endometriosis.Conclusions: Overall, these results underline the importance of controlling for potential confounders in any clinical studies involving blood leukocyte subsets. When adjusting for these parameters, B lymphocytes and a population of monocytes were shown to be modulated in patients with endometriosis compared to controls. Whether these modulations play a role in the development of endometriosis or represent a consequence of the disease remains to be elucidated.Supported By: PROCREA BioSciences. Objective: Previous studies suggest that several leukocyte populations are altered in the peritoneal cavity of patients with endometriosis. The present study is designed to determine whether any immune abnormalities could also be found in other sites such as the peripheral blood. Design: Case-controlled study including 175 patients with endometriosis and 131 disease-free controls. Materials/Methods: Blood mononuclear cells were isolated from peripheral blood by centrifugation through Ficoll-Hypaque. The proportion of CD45+ mononuclear cells expressing surface markers for T, B lymphocytes, monocytes or NK cells or expressing activation molecules was compared by flow cytometry analysis in patients with endometriosis and in normal controls. Several parameters such as age, personal habits, menstrual characteristics and clinical manifestations of endometriosis were taken into account in this study. Results: Age, parity, smoking habit, previous use of oral contraceptives and history of acute infection within the last month influenced significantly the proportion of most leukocyte subsets in the blood and appeared to be important confounders in the present study. When these parameters were carefully controlled, the proportion of B lymphocytes was shown to be significantly decreased in patients with endometriosis compared to controls. On the other hand, the proportion of blood monocytes expressing CD13 and CD44 molecules was shown to be increased in patients with endometriosis. Conclusions: Overall, these results underline the importance of controlling for potential confounders in any clinical studies involving blood leukocyte subsets. When adjusting for these parameters, B lymphocytes and a population of monocytes were shown to be modulated in patients with endometriosis compared to controls. Whether these modulations play a role in the development of endometriosis or represent a consequence of the disease remains to be elucidated. Supported By: PROCREA BioSciences.