Distribution of interleukin-2 receptor α-chain and cells expressing major histocompatibility complex class II antigen in chronic human periapical lesions

In situ distribution of CD2⁺ T-lymphocytes, CD4⁺ and CD8⁺ T-cell subsets, CD14⁺ macrophages, interleukin-2 receptor α-chain (IL-2Rα) and class II major histocompatibility complex antigen (major histocompatibility complex class II, HLA-DR) expressing cells were determined in 14 chronic human periapical granulomas by imrnunohistochemical method using monoclonal antibodies. CD2⁺ lymphocytes were rather evenly distributed within the classical granulation tissue and comprised 55% of the mononuclear cells. Macrophages were distributed all over the periapical area, but their proportion was much less than that of T lymphocytes. Both small, lymphocyte-like mononuclear cells and larger mononuclear cells resembling macrophages displayed mild to strong circumferential staining with the anti-HLA-DR antibody. The majority of lymphocytes expressed IL-2Rα indicating the activated state of T cells within the lesion.