Fig. 3

Neutrophils at healthy human axial enthesis are capable of producing IL-23 upon fungal adjuvant stimulation. A IHC for MPO, human non-inflamed axial enthesis: MPO-expressing neutrophils are present in peri-entheseal bone (3 samples examined). Scale bar (right) represents 100 μm. B MPO-expressing neutrophils are also present in entheseal soft tissue, where they are localized to the blood vessels and are seen marginating (3 examined). Scale bar (right) represents 100 μm. C Digestion of the peri-entheseal bone with subsequent cell sorting also shows that neutrophils are present at/near human axial enthesis (CD45, all leukocytes; CD66b, granulocyte marker; CD16, neutrophil specific marker) (n = 3 samples). D Axial entheseal neutrophils (n = 4 samples) were stimulated with the fungal adjuvant zymosan (0.5mg/ml), zymosan plus IFNγ (20ng/ml) and IFNγ alone for 48 h. IL-23 was measured by a sandwich ELISA for p40 and p19. Paired t test (**p < 0.01)