APOPTOSIS OF CYTOTOXIC T-CELLS IN HISTIOCYTIC NECROTIZING LYMPHADENITIS

Cell death is necrotic or apoptotic. In histiocytic necrotizing lympha denitis (HNL), apoptosis is the main form of cell death, resulting in the creation of nuclear debris that is one of the characteristic featu res of HNL. To investigate the cell type of apoptotic cells, 12 cases of HNL were analyzed using the immunohistochemical staining for TIA-1, a cytotoxic granule of either cytotoxic T or NK cells. One quarter to over half of all apoptotic cells were positive for TIA-1, and some of the nuclear debris was also positive. The necrotic lesions of HNL wer e found to consist of nuclear debris, apoptotic cells, histiocytes and lymphocytes. The lymphocytes were mainly CD8-positive T-cells or CD4- positive cells, while B- and NK cells were only rarely observed. The n umber of TIA-1-positive lymphocytes was more closely related to the nu mber of CD8-positive cells than to the number of CD4 cells. In double staining, the TIA-1 positive lymphocytes were mainly CD8 positive, but rarely CD4 positive. In HNL, then, CD8-positive cytotoxic T-cells are likely to undergo apoptosis.