IL-5–Induced Eosinophils Suppress the Growth ofLeishmania amazonensis In Vivoand Kill PromastigotesIn Vitroin Response to Either IL-4 or IFN-γ

Abstract

In IL-5 transgenic mice (C3H/HeN-TgN(IL-5)-Imeg), in which 50% of peripheral blood leukocytes are eosinophils, the development of infection by Leishmania amazonensis was clearly suppressed. To determine mechanistically how this protozoan parasite is killed, we performed in vitro killing experiments. Either IL-4 or IFN-gamma effectively stimulated eosinophils to kill Leishmania amazonensis promastigotes, and most of the killing was inhibited by catalase but not by the NO inhibitor L-N5-(1-iminoethyl)-ornithine, suggesting that hydrogen peroxide is responsible for the killing of L. amazonensis by eosinophils. There was no significant degranulation of eosinophils in the culture, because eosinophil peroxidase was not detected in culture supernatants when L. amazonensis promastigotes were killed by activated eosinophils. Such resistance was also observed in BALB/c mice, which are highly susceptible to L. amazonensis. Expression plasmids for IL-4, IL-5, and IFN-gamma were transferred into muscle by electroporation in vivo starting 1 week before infection. Expression plasmid for IL-5 was most effective in slowing the development of infection among three expression plasmids. Expression plasmid for IL-4 was slightly effective and that for IFN-gamma had no effect on the progress of disease. These results suggest that IL-5 gene transfer into muscle by electroporation is useful as a supplementary protection method against L. amazonensis infection.

Antitumor Activity of Eosinophils Activated by IL-5 and Eotaxin against Hepatocellular Carcinoma

“…However, this level of eosinophils can be easily obtained by injecting IL-5 expressing plasmid followed by electropolation (Watanabe et al, 2004). This treatment of mice increased the level of eosinophils up to 50% of peripheral white blood cells and 30% of eosinophils were observed 3 weeks after electropolation.…”

Participation of CD11b and F4/80 Molecules in the Conjunctival Eosinophilia of Experimental Allergic Conjunctivitis

“…To examine the latter possibility, the IL-5 gene was introduced into murine muscles by electroporation to increase the eosinophil compartment. Using flow cytometric analysis, we defined the eosinophil compartment on the basis of its high forward and side scatters, as previously reported [11, 12]. We found that most of these cells expressed CD11b and F4/80.…”

“…Fourteen days later, the spleens were harvested and subjected to flow cytometric analysis. As previously reported [11, 12], cells with high levels of side scatter can be regarded as eosinophils. The splenocytes were incubated for 30 min on ice with FITC- or PE-labeled Abs at optimal concentrations and then washed with cold 2% FCS-PBS.…”

“…4). As previously described [11, 12], the granulocytes that are gated on the basis of their high forward and side scatters (gated as R2 in the lower plot of fig. 4) mainly consist of eosinophils.…”

Systemic overexpression of IFN- and IL-5 exacerbates early phase reaction and conjunctival eosinophilia, respectively, in experimental allergic conjunctivitis

“…The splenocytes were then subjected to flow-cytometric analysis to evaluate their forward and side scatters. As previously shown,13 14 cells with high levels of side-scatter are considered to be eosinophils. Splenocytes were stained with FITC-labelled anti-CD3 (145-2C11), FITC-labelled anti-CD45R/B220 (RA3-6B2) or PE-labelled anti-F4/80 (A3-1) (Caltag Laboratories, Burlingame, California).…”