Interleukin 17A (IL-17A) is a proinflammatory
cytokine responsible for the initiation and propagation of
inflammation. One of its actions is the recruitment of neutrophils to the site of
infection. The aim of this study was to investigate whether there is association between
IL-17A expression and neutrophil infiltration in
periapical abscesses and
periapical granulomas, as well as to find which type of T lymphocyte effector (CD4+ or CD8+) expresses
IL-17A in these lesions.
Elastase, CD4, CD8, and
IL-17A were analyzed by immunohistochemistry and immunofluorescence, in the biopsies of periapical lesions.
Abscess lesions exhibited the highest labeling area for
IL-17A (p = 0.011). During double immunofluorescence staining, there were significantly more CD4+/IL-17A+ cells compared to CD8+/IL-17A+ cells, both in the
abscesses (p = 0.025) and
granulomas (p = 0.011). In conclusion,
IL-17A was intensively expressed in
periapical abscesses rich in neutrophils. The high percentage of
IL-17A in these cases suggests the participation of this
cytokine particularly in the acute stages of the inflammatory process of the periapical lesions.