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 eosinophilia (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 the patients, by flow cytometry, and soluble mediators by ELISA or CAP technique. RESULTS: We found an increased number of neutrophils in the effluent from the patient with bacteria-induced peritonitis; accumulation of eosinophils in combination with negative cultures was noted in the patients with PFE. Increased levels of interleukin (IL)-5 and eosinophil cationic protein, but equal levels of eotaxin, were found in effluent from the PFE patients compared to the patient with neutrophilia. Peritoneal fluid eosinophils were activated by means of EG2, CD11b, CD9, and CD69 expression. Compared to blood eosinophils, the cytokine receptors for IL-5 and granulocyte-macrophage colony-stimulating factor, but not IL-3, were down regulated. CONCLUSION: The finding of activated eosinophils in combination with IL-5 and eotaxin in PFE indicates existing similarities between PFE and conditions found during recruitment of eosinophils in allergic inflammatory responses.