Figure 2 IL‐8 production by CD40L‐stimulated HIFs. Panel A: Human intestinal fibroblasts (HIFs) were activated with soluble CD40 ligand (sCD40L) or were co‐cultured either with CD40⁺ D1.1 cells or with CD40⁻ Jurkat cells for 24 hours, before measuring interleukin‐8 (IL‐8) release in culture supernatants. In selected experiments, blocking antibodies (Ab) to either CD40 (M2) or CD40L (M90) were used to interfere with the CD40–CD40L interaction. Results are representative of eight independent experiments performed in duplicate and are expressed as mean and standard deviation. *p<0.001 compared with IL‐8 release by HIFs not activated with sCD40L; **p<0.001 compared with IL‐8 release by HIFs cultured in the absence of CD40⁺ D1.1 cells; ^§p<0.001 compared with IL‐8 release in the absence of blocking antibodies to either CD40 or CD40L. Panel B: HIFs were co‐cultured either with unstimulated lamina propria T (LPT) cells or with CD40L⁺ activated LPT cells. In selected experiments, blocking antibodies to either CD40 (M2) or CD40L (M90) were used to interfere with the CD40–CD40L interaction. **p<0.001 compared with IL‐8 release by HIFs cultured in the absence of CD40⁺ LPT cells; ^§p<0.001 compared with IL‐8 release in the absence of blocking antibodies to either CD40 or CD40L