Density-dependent immune responses against the gastrointestinal nematode Strongyloides ratti - PubMed (original) (raw)

Density-dependent immune responses against the gastrointestinal nematode Strongyloides ratti

Colin Bleay et al. Int J Parasitol. 2007 Nov.

Abstract

Negative density-dependent effects on the fitness of parasite populations are an important force in their population dynamics. For the parasitic nematode Strongyloides ratti, density-dependent fitness effects require the rat host immune response. By analysis of both measurements of components of parasite fitness and of the host immune response to different doses of S. ratti infection, we have identified specific parts of the host immune response underlying the negative density-dependent effects on the fitness of S. ratti. The host immune response changes both qualitatively from an inflammatory Th1- to a Th2-type immune profile and the Th2-type response increases quantitatively, as the density of S. ratti infection increases. Parasite survivorship was significantly negatively related to the concentration of parasite-specific IgG(1) and IgA, whereas parasite fecundity was significantly negatively related to the concentration of IgA only.

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Figures

Fig. 1

Fig. 1

The mean concentration of (a) IL-4, (b) IL-13 and (c) IFN-γ by mesenteric lymph node (MLN) cells stimulated with parasitic female antigen from animals infected with different doses of Strongyloides ratti, where x = 0, ○ = 6, • = 30, ▵ = 150, ▴ = 750 infective larvae at different days p.i. (d.p.i.). Error bars are ±1 SEM.

Fig. 2

Fig. 2

Vectors calculated as the mean within-infective dose concentration of IFN-γ and IL-4 of mesenteric lymph node (MLN) cells stimulated with parasitic female antigen, compared with the mean values of the control animals (dose = 0) at 8, 15 and 22 days p.i. (d.p.i.), where x = 0, ○ = 6, • = 30, ▵ = 150, ▴ = 750 infective larvae. Large symbols are the means for each dose treatment; small symbols are individual data points.

Fig. 3

Fig. 3

The mean concentration of (a) parasite-specific IgA in intestinal tissue; (b) total serum IgE; parasite-specific serum; (c) IgG2a; (d) IgG2b; (e) IgG1 and (f) RMCP II in intestinal tissue from animals infected with different doses of Strongyloides ratti, where x = 0, ○ = 6, • = 30, ▵ = 150, ▴ = 750 infective larvae at different days p.i. (d.p.i.). Error bars are ±1 SEM.

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