Small intestinal pro-inflammatory immune cell responses following ileitis induction. Pro-inflammatory immune cell responses were assessed in ileal paraffin sections derived from C57BL/6 wildtype (WT; black circles) and TLR-9 deficient (TLR-9-/-; white circles) mice seven days following ileitis induction (ILE) applying in situ immunohistochemistry. The average numbers of ileal (A) apoptotic cells (positive for caspase-3; Casp3), (B) neutrophilic granulocytes and monocytes (positive for MPO-7), (C) macrophages (positive for F4/80), (D) T lymphocytes (positive for CD3), and (E) regulatory T cells (Treg, positive for FOXP3) were determined in six high power fields (HPF, 400 × magnification) per animal by light microscopy. Naïve mice served as negative controls (N). Numbers of analyzed mice (in parentheses), means (black bars) and levels of significance (P-values) as compared to the respective groups (determined by Mann–Whitney-U test) are indicated. Data shown were pooled from three independent experiments.