Phenotypic alterations of recruited eosinophils in peritoneal fluid eosinophilia

Objective:To characterize eosinophils and soluble factors in effluent from continuous ambulatory peritoneal dialysis (CAPD) patients and connect these findings to related conditions with eosinophilic accumulation. Patients: Three newly started CAPD patients, two with peritoneal fluid eosi nophilia (PFE) and one with bacteria-induced peritonitis. One patient with PFE was followed up for 10 visits during a 7-month period. Methods: Leukocytes were analyzed in dialysate and peripheral blood from th e patients, by flow cytometry, and soluble mediators by ELISA or CAP techni que. Results: We found an increased number of neutrophils in the effluent from t he patient with bacteria-induced peritonitis; accumulation of eosinophils i n combination with negative cultures was noted in the patients with PFE. In creased levels of interleukin (IL)-5 and eosinophil cationic protein, but e qual levels of eotaxin, were found in effluent from the PFE patients compar ed to the patient with neutrophilia. Peritoneal fluid eosinophils were acti vated by means of EG2, CD11b, CD9, and CD69 expression. Compared to blood e osinophils, the cytokine receptors for IL-5 and granulocyte-macrophage colo ny-stimulating factor, but not IL-3, were down regulated. Conclusion: The finding of activated eosinophils in combination with IL-5 a nd eotaxin in PFE indicates existing similarities between PFE and condition s found during recruitment of eosinophils in allergic inflammatory response s.