KINETICS OF SERUM AND CELLULAR INTERLEUKIN-5 IN POSTTREATMENT EOSINOPHILIA OF PATIENTS WITH LYMPHATIC FILARIASIS

Peripheral blood eosinophil counts and serum levels and in vitro produ ction of eosinophilopoetic cytokines were assessed before and at frequ ent intervals after diethylcarbamazine treatment of Bancroftian filari asis. Eosinophil counts peaked at day 7 after the start of treatment ( 359% +/- 118% of pretreatment levels) and declined to pretreatment lev els by day 17. Serum interleukin (IL)-5, undetectable in 14 of 15 pati ents before treatment, rose sharply but transiently, with peak levels (32 +/- 7 pg/mL) 2 days after diethylcarbamazine treatment. Granulocyt e-macrophage colony-stimulating factor and IL-3 were not detectable in serum at any time. In vitro mitogen-induced IL-5 levels decreased sig nificantly in 7 of 9 patients 3 days after treatment when serum IL-5 w as at near-peak levels. By day 10 IL-5 values increased in 8 of 9 pati ents compared with treatment values (P < .02). These data define the t emporal relation between serum IL-5 levels and the subsequent developm ent of eosinophilia and suggest that lymphocytes are the source of IL- 5.