HEMOPHAGOCYTOSIS AS A PARA-NEOPLASTIC SYNDROME IN NK CELL LEUKEMIA

Hemophagocytic syndrome is a proliferative disorder of an activated mo nocyte-macrophage system and is characterized by fever, hepato-splenom egaly and pancytopenia. The serum level of interferon-gamma in the syn drome is increased but its origin is unknown, Here we describe a case of NK cell leukemia with hemophagocytic syndrome with elevated serum l evel of interferon-gamma. The levels of various cytokines were monitor ed during the course and statistic analysis was performed, To identify the clonal component, the NK cell fraction was sorted from the mononu clear layer and was subjected to Southern blot hybridization with a pr obe for EB virus tandem repeats. The fraction was also stimulated with interleukin-2 and the level of interferon-gamma in the conditioned me dium was measured. Levels of M-CSF and interferon-gamma were significa ntly correlated with the degree of clinical manifestations and laborat ory data. Southern blot hybridization revealed monoclonality of an NK cell fraction. The fraction also released interferon-gamma, Since macr ophage can be activated through cytokines, the hemophagocytosis might have been triggered by factor(s) released from the abnormal NK cell cl one at least in this case.