Figure 3.

Emergence of CCR2⁺ TCRαβ⁺CD4⁺ IEL correlates with maximum pathology during Toxoplasma infection. IEL were isolated and stained with anti-CCR2 mAb (A, which shows CCR2 expression on IEL from Day 4-infected mice), in combination with Ab specific for CD4, CD8α, CD8β, αβTCR and γδTCR. Panel B shows respective expression of CD8α and CD4 in CCR2⁻ and CCR2⁺ populations over the course of infection. Essentially identical results were obtained in 3 independent experiments. To examine if Toxoplasma-triggered recruitment of TCRαβ⁺CD4⁺ to the IEL compartment is dependent upon CCR2, IEL were isolated from WT and Ccr2^−/− mice 8 days after infection and expression of CD8α and CD4 was assessed. Representative staining profiles are shown in panel C, which also shows the average percent of CD4⁺ IEL in day 8-infected mice in 3 independent experiments (*, p<0.05). Panel D shows TCRαβ and TCRγδ expression on CD4⁺ and CD8α⁺ IEL, respectively, from Day 8-infected WT mice.