[Current and future directions of pathologic analysis in hemophagocytic syndrome]

Hemophagocytic syndrome is a rare disorder with dysfunction of cytotoxic T lymphocyte (CTL) or NK cell activity, leading to excessive production of inflammatory cytokines and various clinical symptoms. HLH can be classified as either primary or secondary form; primary HLH includes familial hemophagocytic lymphohistiocytosis (FHL) and several immune deficiencies. All affected genes are involved in the transport and membrane fusion, or exocytosis of perforin/granzyme in lytic granules. Making a rapid screening of FHL with flow cytometry followed by genetic analysis is mandatory for the appropriate treatment of this fatal disease. Whereas, pathogenesis of secondary HLH is still unknown; several genetic backgrounds to affect on the pathway of T-cell activity will be associated with secondary HLH. With perforin- or Munc-deficient mouse model that develop HLH-like symptoms after virus infection, CD8+ T cells and interferon-gamma have been proven to be necessary for the HLH development. These data will provide new targets for specific therapeutic intervention of HLH in the future.