Eosinophilic interleukin 5 (IL‐5) transgenic mice: eosinophil activity and impaired clearance of Schistosoma mansoni

Abstract

Eosinophilia is a feature common to many invasive helminth infections and eosinophils are often considered to be effector cells in immunity to helminths. This study examined the possible influence of constitutive eosinophilia on the clearance of Schistosoma mansoni infections in mice. Eosinophils from interleukin-5 transgenic mice exhibit normal ultrastructure and function with regard to phagocytosis and killing of bacteria and responses to chemotactic stimuli. IL-5 transgenics and non-transgenic littermates were immunized once or four (hyperimmunization) times with irradiated cercariae of S. mansoni. Animals were challenged percutaneously with unirradiated cercariae one month after their last exposure to irradiated parasites. One month after challenge transgenic animals, whether unimmunized, vaccinated or hypervaccinated, carried significantly more liver-stage parasites than non-transgenic animals. These results suggest that although eosinophils from IL-5 transgenic mice are functional for a number of key parameters, large numbers of eosinophils and/or high levels of IL-5 may in some way impair clearance of S. mansoni. A re-evaluation of the roles of eosinophils and IL-5 in infections with this and other parasites may therefore be warranted.

Slit2 Regulates Attractive Eosinophil and Repulsive Neutrophil Chemotaxis through Differential srGAP1 Expression during Lung Inflammation

“…As IL-5 critically mediates eosinophil maturation, survival, activation, and chemotaxis (32), IL-5-Tg mice have been used extensively for a variety of studies, such as eosinophil migration and chemotaxis (52) and phagocytosis (53). In this study, we have isolated mouse eosinophils from IL-5-Tg mice for in vitro experiments of eosinophil polarization, migration, and chemotaxis.…”

Immune responses of IL-5 transgenic mice to parasites and aeroallergens

“…We addressed the possibility that IL-5 transgenics might not spontaneously develop respiratory disease when kept in conventional conditions because of abnormalities in many of the eosinophils which they carry. Much of this has recently been described (Dent et al 1997). Eosinophils from IL-5 transgenics have many eosinophilic granules and at least as many as those found in eosinophils recovered from untreated or parasite-infected nontransgenic littermates (Dent et al 1997).…”

“…Much of this has recently been described (Dent et al 1997). Eosinophils from IL-5 transgenics have many eosinophilic granules and at least as many as those found in eosinophils recovered from untreated or parasite-infected nontransgenic littermates (Dent et al 1997). Many but not all of these granules have one or more electron dense bodies at the core, an ultrastructural feature typical of eosinophil granules (Fig.…”

“…Although on a cell-for-cell basis individual neutrophils from non-transgenic mice appear to phagocytose more bacteria than eosinophils from IL-5 transgenics (unpublished data), we have yet to determine if eosinophils can only kill bacteria after internalization. Regardless of their principal method of killing, eosinophils from IL-5 transgenic mice compare in efficiency to neutrophils from non-transgenic mice in destroying Gram-negative bacteria (Proteus mirabilis) opsonized with immune serum and both are more efficient than eosinophils recovered from the site of an M. corti infection in non-transgenic mice (Dent et al 1997).…”

Role of IL-5 in Innate and Adaptive Immunity to LarvalStrongyloides stercoralisin Mice

“…Parasites for which there was no correlation between the levels of IL-5 and the survival, growth, or fecundity of the parasite include Schistosoma mansoni (12), Trichinella spiralis (11), Toxocara canis (13), and Trichuris muris (10). One report even showed impairment in the successful clearance of S. mansoni from IL-5 transgenic mice following immunization (14). These data suggest that, although IL-5 is elevated in response to these infections, the cytokine is not required for immune protection against these species of parasitic helminths.…”