Régulation des populations de Nématodes gastro-intestinaux ...

Résultats
present as early as 4 days post-challenge in the previously-infected groups (groups A). In
contrast, higher mRNA gene expression was only observed at 30 dpc in the primary-infected
groups (groups B) and reached similar or higher levels compared to those of groups A. Thirty
days post challenge, the IL-4, IL-5 and IL-13 mRNA transcription levels were significantly
higher in the abomasal lymph nodes of infected BBB lambs than in infected INRA 401 lambs
(P < 0.05). At least for IL-5, this breed difference was associated to a sharp drop in the level
of cytokine transcription in both INRA 401 groups compared to its level at 4 dpc. In contrast,
no breed differences were encountered for these cytokines in the abomasal fundic mucosa.
Similarly, no significant group or breed differences were noticed in IFN-γ, IL-12, IL-10,
TNF-α and Eotaxin mRNA transcription profiles both at 4 and 30 dpc.
3.3. Effector cells recruitment in blood and abomasal tissues
3.3.1. Kinetics of blood eosinophilia during infections
In the control groups, blood eosinophil counts remained low and stable during the
whole experiment (Figure 2). Nevertheless, these counts for control animals were higher in
BBB lambs when compared to those of INRA 401 lambs (P < 0.001) throughout the
experimental period. Each experimental infection was followed one week later by an increase
in blood eosinophil counts. Peak values were attained two to three weeks after infection. In
spite of the strong individual variability observed in infected groups, blood eosinophilia was
higher in BBB than in INRA 401 lambs in initial as well as in challenge infections (P < 0.01).
After anthelminthic treatment, eosinophil counts returned to pre-infection levels in INRA 401
lambs but remained higher than control values in BBB lambs. Moreover, the challenge
infection in BBB was followed by further increase in blood eosinophils counts (P = 0.04)
compared to the initial infection, which later declined but remained still higher than the
control values. In contrast, no difference was observed between the two successive infections
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