S100A8 and S100A9 calcium-binding proteins: localization within normal and cyclosporin A-induced overgrowth gingiva.

S100A8 and S100A9, also called myeloid related protein (MRP) 8 and 14, are calcium-binding proteins highly expressed in neutrophils, in which they play a key role in the inflammatory progression. In this study, we looked at the expression of S100A8/A9 within gingiva from normal and Cyclosporin A (CsA)-induced overgrowth gingiva. In gingiva from the CsA group, several positive S100A8/A9 cells were seen within the connective tissue, whereas in normal gingiva very few positive S100A8/A9 cells were detected. These cells correspond either to activated macrophages or to neutrophils, reflecting the well-known gingival inflammatory status associated with the CsA-treated group. In addition, in both the normal and drug-treated group, the gingival epithelia appeared S100A8/A9 immunopositive. More specifically, S100A8/A9 appeared in the majority within the spino-cellular layer and located extracellularly within the desmosomes. In addition, S100A8/A9 also appeared sporadically intracellularly, located within the cytoplasm and the nuclei, reflecting S100A8/A9 translocations.