Blood-donation screening for antibodies to and DNA from B. microti was associated with a decrease in the risk of transfusion-transmitted babesiosis. (Funded by the American Red Cross and Imugen; ClinicalTrials.gov number, NCT01528449 .).

The relative contributions of local T helper cell type 1 (Th1)- and Th2-like responses to the course of primary and secondary gastrointestinal (GI) candidiasis were examined in adult immunocompetent BALB/c mice. Both Th1 cytokines, such as interferon-gamma (IFN-gamma), and the Th2 cytokines, interleukin (IL)-4 and IL-5, were produced by CD4+ cells from Peyer's patches (PP) and mesenteric lymph nodes at a time when the fungus was cleared from the stomach and intestine. Augmentation of antigen-specific Th2-like responses by treatment with cholera toxin did not modify the course of disease. In contrast, treatment with soluble IL-4 receptor, which increased Th1 cells, was associated with enhanced yeast clearance. In addition, IFN-gamma but not IL-4 mRNA was present in PP and spleen CD4+ cells in mice resistant to subsequent GI inoculation. Activation of Th1- but not Th2-like responses may be responsible locally for controlling GI candidiasis and generating protective immunity.

Transfusion-transmitted B. microti can be a significant cause of transfusion-related morbidity and mortality, especially in infant, elderly, and asplenic blood recipients. These data demonstrate the need for interventions, in both endemic and nonendemic areas of the United States, to reduce patient risk.

Studying apoptosis induced by T cell receptor (TCR) cross-linking in the T cell hybridoma, 3DO, we found both neutral sphingomyelinase activation and production of ceramide upon receptor engagement. Pharmacological inhibition of ceramide production by the fungal toxin, fumonisin B1, impaired TCR-induced interleukin (IL)-2 production and programmed cell death. Addition of either exogenous ceramide or bacterial sphingomyelinase reconstituted both responses. Moreover, specific inactivation of neutral sphingomyelinase by antisense RNA inhibited IL-2 production and mitogen-activated protein kinase activation after TCR triggering. These results suggest that ceramide production by activation of neutral sphingomyelinase is an essential component of the TCR signaling machinery.