Granzyme M (GrM) is a novel cytotoxic protein normally exclusively expressed by natural killer (NK)-cells and cytotoxic T-cells with innate immune function. As most T-cell granular lymphocytic leukaemias (T-LGL) are thought to be derived from the adaptive immune system it was predicted that T-LGL would be GrM negative. Contrary to this hypothesis, bone marrow biopsy immunohistochemistry revealed that GrM was frequently expressed in both T-LGL (16 / 18) and NK-LGL (6 / 9). These unexpected results suggest commonality between T- and NK-LGL, providing further support to the notion that T-LGL is a disorder of dysregulated, chronically stimulated, adaptive cytotoxic T-cells.
- Large granular lymphocytic leukaemia
- Natural killer-cell
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