Haemophagocytic syndrome or haemophagocytic lymphohistiocytosis is a rare disease that is often fatal despite treatment. Haemophagocytic syndrome is caused by a dysregulation in natural killer T-cell function, resulting in activation and proliferation of lymphocytes or histiocytes with uncontrolled haemophagocytosis and cytokine overproduction. The syndrome is characterised by fever, hepatosplenomegaly, cytopenias, liver dysfunction, and hyperferritinaemia. Haemophagocytic syndrome can be either primary, with a genetic aetiology, or secondary, associated with malignancies, autoimmune diseases, or infections. Infections associated with haemophagocytic syndrome are most frequently caused by viruses, particularly Epstein-Barr virus (EBV). We present a case of EBV-associated haemophagocytic syndrome in a young adult with no known immunosuppression. We briefly review haemophagocytic syndrome and then discuss its associated infections, particularly EBV and other herpes viruses, HIV, influenza, parvovirus, and hepatitis viruses, as well as bacterial, fungal, and parasitic organisms.

tolerance is low in strains with a functional calcineurin and is high in strains which lack calcineurin activity. In contrast, the contribution of PMC1 to Ca 2؉ tolerance is augmented by calcineurin activation. Consistent with these positive and negative roles of calcineurin, expression of a vcx1::lacZ reporter was slightly diminished and a pmc1::lacZ reporter was induced up to 500-fold by processes dependent on calcineurin, calmodulin, and Ca 2؉. It is likely that calcineurin inhibits VCX1 function mainly by posttranslational mechanisms. Activities of VCX1 and PMC1 help to control cytosolic free Ca 2؉ concentrations because their function can decrease pmc1::lacZ induction by calcineurin. Additional studies with reporter genes and mutants indicate that PMR1 and PMR2A, encoding P-type ion pumps required for Mn 2؉ and Na ؉ tolerance, may also be induced physiologically in response to high-Mn 2؉ and -Na ؉ conditions through calcineurin-dependent mechanisms. In these situations, inhibition of VCX1 function may be important for the production of Ca 2؉ signals. We propose that elevated cytosolic free Ca 2؉ concentrations, calmodulin, and calcineurin regulate at least four ion transporters in S. cerevisiae in response to several environmental conditions.

Ca 2÷ signaling plays an important role in the activation of T cells (Gardner, 1989). Binding of antigens to specific receptors at the surface of quiescent T cells triggers the opening of Ca 2÷ channels in the endoplasmic reticulum and plasma membrane, leading to rapid elevation in [Ca2÷]c.