The effect of specific immunization or infection with Trichostrongylus colubriformis on production of eosinophil differentiation factors in guinea pigs

Abstract

The cultivation of bone marrow was used to quantitate the levels of eosinophil differentiation factors (EDF) produced in conditioned medium (CM) by incubation of mesenteric lymph node cells (MLNC) with mitogens or specific antigens from the intestinal nematode parasite, Trichostrongylus colubriformis. In liquid cultures with 20 units ml −1 recombinant murine interleukin-5 (IL-5), bone marrow cells (BMC) from either normal or infected donors contained <5% eosinophils and differentiated to > 50% eosinophils over 2–3 weeks. Conditioned medium from 3–4 week infected donors produced between 20 and 50% eosinophils when donor MLNC were stimulated with the specific antigen preparation SP3, but macrophages predominated when using CM from MLNC incubated with Concanavalin A (ConA). CM from MLNC of challenged donors incubated with SP3 produced 30–70% eosinophils in BMC assays, with highest levels induced by CM from high responder (HR) donors. Marrow from parasitized or normal donors gave rise to comparable proportions of eosinophils. CM was also produced from LNC of donors given protein or parasite antigens in adjuvant where between 28 and 35% eosinophils were produced in culture. There were no differences between activities attributable to the antigen, but Freund's complete adjuvant induced earlier differentiation of BMC than alum-induced CM. The results confirm that high levels of EDF activity are specifically induced by parasitic infection, and can also be produced by intraperitoneal and subcutaneous inoculation of adjuvanted antigens. Consistent with the greater eosinophilia exhibited by HR guinea pigs to infection with T.colubriformis L3, their MLNC also produced the highest levels of EDF activity.