Figure 3

Lung-resident CD4⁺ T-cell population are sufficient to confer protection against secondary Nippostrongylus brasiliensis (NB) infection. (a) FTY720-treated and untreated mice were given a primary (1^o) or secondary (2^o) N. brasiliensis infection. Primary infections were cleared at day 7 by Ivermectin treatment, and mice were subsequently reinfected at day 28 and killed at day 2 or day 5 post infection (PI). Ability to resolve infection was established by quantification of (b) lung worm burdens and (c) intestinal worm burdens at day 2 and day 5 post infection, respectively. (d) Flow cytometric analysis of cell suspension of whole lung stained for CD3⁺CD4⁺, CD3⁺CD8⁺, CD4⁺CD44^loCD62L^hi naive, and CD4⁺CD44^hiCD62L^lo effector memory T cells at 5 days post secondary infection. Whole-cell preparations of lung were re-stimulated with N. brasiliensis excretory secretory proteins for 5 days, and (e) cytokine secretion for interleukin (IL)-4 and IL-13 was detected by enzyme-linked immunosorbent assay. (f) Confocal microscopic images of frozen sections of the lung stained with antibody to CD3 (green) and counterstained with Hoechst (blue) around the peri-bronchial and interstitial areas of the lung. White arrows indicate CD3⁺ T cells. Bar=50 μm (data are representive of one individual experiment, N=8 mice per group). Numbers in the flow cytograms indicate the percentage of T cells present relative to total cell numbers. Data are representative of two individual experiments. N=6–10 mice per group. *P<0.05, **P<0.01.

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