Improvement of extrathymic T cell type of large granular lymphocyte (LGL) leukemia by cyclosporin A: the serum level of Fas ligand is a marker of LGLleukemia activity

We report a case of y delta T-cell-type large granular lymphocyte (LGL) leu kemia (CD3 +,CD8 +, CD57 +,TCR y delta +), which was accompanied by pure re d cell aplasia, neutropenia and thrombocytosis. Southern blotting analysis of the T-cell receptor beta gene showed the germline configuration, but clo nal TCR J gamma rearrangements were identified. These granular lymphocytes demonstrated non-major histocompatibility complex-restricted cytotoxicitity . The serum-soluble FasL (sFasL) concentration of this patient was very hig h, whereas the serum levels of tumor necrosis factor alpha (TNF-alpha, inte rferon gamma (IFN-gamma), interleukin-l beta (IL-1 beta), interleukin-2 (IL -2) and thrombopoietin were normal. After treatment with cyclosporin A, ane mia and thrombocytosis were improved, and LGL and the elevated sFasL concen tration decreased. These observations suggested that FasL may have played a role in the establishment of the clinical symptoms of this patient and cou ld be useful as an indicator of disease activity.