No abstract

The most common form of neutrophil death, under both physiological and inflammatory conditions, is apoptosis. In this study, we report a novel form of programmed necrotic cell death, associated with cytoplasmic organelle fusion events, that occurs in neutrophils exposed to GM-CSF and other inflammatory cytokines upon ligation of CD44. Strikingly, this type of neutrophil death requires PI3K activation, a signaling event usually involved in cellular survival pathways. In the death pathway reported in this study, PI3K is required for the generation of reactive oxygen species, which somehow trigger the generation of large cytoplasmic vacuoles, generated by the fusion of CD44-containing endosomes with autophagosomes and secondary, but not primary, granules. Neutrophils demonstrating vacuolization undergo rapid cell death that depends on receptor-interacting protein 1 kinase activity and papain family protease(s), but not caspases, that are most likely activated and released, respectively, during or as a consequence of organelle fusion. Vacuolized neutrophils are present in infectious and autoimmune diseases under in vivo conditions. Moreover, isolated neutrophils from such patients are highly sensitive toward CD44-mediated PI3K activation, reactive oxygen species production, and cell death, suggesting that the newly described autophagy-related form of programmed neutrophil necrosis plays an important role in inflammatory responses.

No abstract

No abstract

Hemophagocytic lymphohistiocytosis (HLH) is a rare condition with high mortality. We report an extremely premature girl, born in the 24th gestational week (BW 732 g), that during her second month developed a severe HLH subsequent to a Serratia marcescens septicemia, with hepatosplenomegaly, cytopenias, hyperbilirubinemia (mostly conjugated, total bilirubin 916 mumol/L), hypertriglyceridemia, hypofibrinogenemia, hyperferritinemia (21266 mug/L), and elevated sIL-2 receptor levels. Genetic analysis revealed no PRF1, STX11 or UNC13D gene mutations. Treatment was provided according to the HLH-2004 protocol with etoposide, dexamethasone, and immunoglobulin, but no cyclosporin because of immature kidneys. She recovered fully from the HLH but developed a severe retinopathy as well as green teeth secondary to the hyperbilirubinemia. We conclude that secondary, bacteria-associated HLH can develop in premature infants, and that HLH can be treated with cytotoxic therapy also in premature infants. It is important to be aware of HLH in premature infants, since it is treatable.

No abstract

No abstract

Objective: In an experimental setting, human basophil degranulation was triggered by anti-IgE to measure the effects from homeopathic solutions in an in-vitro cell system. A 3-color flow cytometric method with enhanced accuracy was established. As an example we looked at the influence of histamine on anti-IgE activation of basophils. Methods: Basophils were identified in the flow cytometer by their physical properties in the forward and side scatter light depiction and by gating on CD2^–, CD14^–, CD16^–, CD19^–, HLA-DR^– negative and CD123-positive cells. CD63 expression on the cell surface of the anti-IgE-activated basophils served as an activation marker. Results: With this method we were able to study basophil function of the 0.6–3.9% basophils out of the mononuclear blood cell fraction and to document their activation status upon anti-IgE activation. Optimal activation occurs at 0.6 µg/ml final anti-IgE concentration; not less than 10,000 basophils have to be counted per batch to reduce the variation of the measurement. The fixation method was able to stabilize activation for two days. After investigation and reduction of the source of measurement variability, an unequivocally inhibited basophil activation was documented in a partly optimized system with homeopathic dilutions of histamine (10^–22M, 10^–23M, 10^–24M, and 10^–25M histamine). Dilutions greater than 10^–20M histamine (Avogadro’s number 6.02 × 10²³) account for less than 1.36 molecules of histamine in the test sample, indicating a true homeopathic effect. Conclusions: This test system is adequate for studying the effects of highly diluted mediators on basophil activation by anti-IgE. The systematic application of this experimental arrangement is recommended to study the effects of homeopathic dilutions on basophils.