Production of interleukin‐8 in vitro by mononuclear cells isolated from human periapical lesions

Introduction: Interleukin‐8 (IL‐8) is an important mediator of inflammation. However, little is known about its production in chronic dental periapical lesions and this was the main aim of this work. Methods: Inflammatory cells were isolated from clinically different periapical lesions and analyzed by morphological criteria. The mononuclear cells were isolated, phenotypically analyzed by immunocytochemistry and cultivated in vitro. IL‐8 was measured in culture supernatants of these periapical lesion mononuclear cells (PL‐MNC) using a microbeads fluorescence assay. Results: We found a relatively high production of IL‐8 in 19 out of 21 periapical lesions included in the study. The level of IL‐8 and the proportion of neutrophil granulocytes were significantly higher in the group of symptomatic lesions, compared to the asymptomatic lesions, but there was no statistically significant correlation between these parameters. According to the predominance of CD3⁺ T cells and Ig⁺/CD19⁺ B cells and plasma cells, lesions were divided into T‐type and B‐type lesions, respectively. The levels of IL‐8 were significantly higher in the culture supernatants of PL‐MNC in the T‐type lesions and were positively correlated with the proportion of macrophages/dendritic cells (CD11c⁺ cells) and CD4⁺ T cells. Such a correlation was not shown in B‐type lesions. Conclusion: These results suggest that PL‐MNC are a significant source of IL‐8, which is probably an important chemokine for the migration and function of different cell types at the site of chronic inflammation.