Effects of <i>Toxocara canis </i>Infection on Hemopoietic Stem Cells and Hemopoietic Factors in Mice

Abstract

The effects of Toxocara canis infection on hemopoietic stem cells and hemopoietic factors were examined in mice. Severe eosinophilia was observed with a peak 14 days after infection. When the numbers of hemopoietic stem cells in peripheral blood, spleen, and bone marrow were examined by spleen colony assay (CFU-S), those in peripheral blood and spleen increased in parallel with peripheral blood eosinophilia. On the other hand, CFU-S in bone marrow did not alter significantly throughout the course of infection. Interleukin (IL)-3, which is known as multi-colony-stimulating factor and is involved in the growth/differentiation of various blood cells including stem cells, was produced by spleen cells of infected mice. The time course study showed that concanavalin A stimulated IL-3 production peaked on day 7 after infection, whereas that with excretory secretory antigen peaked on day 14. Even without stimulation, spleen cells obtained on day 21 after infection produced IL-3 spontaneously. IL-5, which is known to have eosinophil differentiation factor activity, was also produced by spleen cells obtained on day 13 after infection. These results suggest that in response to increased demand for eosinophils, hemopoietic stem cells migrate into various extramedullar hemopoietic organs where they grow/differentiate into mature eosinophils, depending on the hemopoietic factors.

Mechanisms of eosinophilia in Toxocara canis infected mice: In vitro production of interleukin 5 by lung cells of both normal and congenitally athymic nude mice

“…Because no EDA was detected in media conditioned by lungs and spleen cells of non-infected nu/nu and nu/+ mice, IL-5 production by lung cells of both mice and spleen cells of nu/+ mice was an effect related to infection. Although IL-5 production by spleen cells of T. canis infected mice were reported previously (Higa et al 1990, Yamaguchi et al 1990), we reported here for the first time that lung cells of infected nu/nu and nu/+ mice produced IL-5 when stimulated by antigen. These results indicate the mechanism of eosinophilia in T. canis infected nujnu mice.…”