Characterization of distribution of T lymphocyte subsets and activated T lymphocytes infiltrating into sarcoid lesions.

We studied the relationship between various T lymphocyte functions and granuloma formation in 5 lung tissue and 4 lymph node tissue samples from patients with sarcoidosis by immunohistological methods. In the lesion of sarcoidosis, T cells were positive for alpha beta TCR, but gamma delta TCR-positive T cells were rarely observed. The results of analysis of functional subsets showed that T cells in the internal area of granuloma were predominantly helper/inducer subset (CD4+CD45RA-). On the other hand, cytotoxic T cells (CD8+CD45RA-CD11b-) were present in abundance in the outer boundaries of granuloma. In addition, suppressor-inducer T cells (CD4+CD45RA+) were present in the surrounding areas. However, T cells of various subsets were present sporadically outside the granulomas. We also studied the distribution of T cells expressing activation-related antigens. The results showed that T lymphocytes in the internal area of granulomas more frequently had these antigens than did T lymphocytes in the external area. These findings suggested that T cells infiltrating into the sarcoidosis lesion demonstrated a layer-like distribution based on functional subsets. These findings also confirm that activated T cells were more abundantly distributed in the internal area of sarcoid granuloma than in the external area.