Effects of recombinant GM-CSF and IgA opsonisation on neutrophil phagocytosis of latex beads coated with P6 outer membrane protein from Haemophilus influenzae

Monosodium urate crystals induce extracellular DNA traps in neutrophils, eosinophils, and basophils but not in mononuclear cells

Neutrophil extracellular traps (NETs) are fibers of extracellular DNA released from neutrophils due to overwhelming phagocytic stimuli. The function of NETs is to trap and kill microbes to avoid spreading of potential pathogens. NETs are formed after encounter with various gram-positive and -negative bacteria but also in response to mediators causing sterile inflammation like interleukin-8 (IL-8), tumor necrosis factor (TNF), and phorbol myristate acetate (PMA). Here we show the formation of NETs (NETting) in response to monosodium urate (MSU) crystals as further model for sterile inflammation. We identified monocytes, neutrophils, and eosinophils as MSU phagocytosing cells. Basophils did not take up the crystals, instead they upregulated their activation marker CD203c after contact with MSU. Nevertheless, MSU crystals induced extracellular trap formation also in basophils, like in eosinophils and neutrophils, which phagocytose the crystals. In contrast, monocytes do not form NETs despite uptake of the MSU crystals. In contrast to the canonical stimuli like bacteria and PMA, MSU-induced NETosis was not abrogated by plasma. Our data show that MSU crystals induce extracellular DNA trap formation in all three granulocytes lineages (NETs, EETs, and BETs) but not in monocytes, and DNA externalization does not necessitate the uptake of the crystals.

IgA Fc receptors

The IgA receptor family comprises a number of surface receptors including the polymeric Ig receptor involved in epithelial transport of IgA/IgM, the myeloid specific IgA Fc receptor (FcalphaRI or CD89), the Fcalpha/muR, and at least two alternative IgA receptors. These are the asialoglycoprotein receptor and the transferrin receptor, which have been implicated in IgA catabolism, and tissue IgA deposition. In this review we focus on the biology of FcalphaRI (CD89). FcalphaRI is expressed on neutrophils, eosinophils, monocytes/macrophages, dendritic cells, and Kupffer cells. This receptor represents a heterogeneously glycosylated transmembrane protein that binds both IgA subclasses with low affinity. A single gene encoding FcalphaRI has been isolated, which is located within the leukocyte receptor cluster on chromosome 19. The FcalphaRI alpha chain lacks canonical signal transduction domains but can associate with the FcR gamma-chain that bears an activation motif (ITAM) in the cytoplasmic domain, allowing activatory functions. FcalphaRI expressed alone mediates endocytosis and recyling of IgA. No FcalphaRI homologue has been defined in the mouse, and progress in defining the in vivo role of FcalphaRI has been made using human FcalphaRI transgenic (Tg) mice. FcalphaRI-Tg mice demonstrated FcalphaRI expression on Kupffer cells and so defined a key role for the receptor in mucosal defense. The receptor functions as a second line of antibacterial defense involving serum IgA rather than secretory IgA. Studies in FcalphaRI-Tg mice, furthermore, defined an essential role for soluble FcalphaRI in the development of IgA nephropathy by formation of circulating IgA-FcalphaRI complexes. Finally, recent work points out a role for human IgA in treatment of infectious and neoplastic diseases.

Effect of tear secretory IgA on chemotaxis of polymorphonuclear leucocytes

PURPOSE

The aim of the present study was to examine the effect of tear and purified colostrum secretory IgA (sIgA) on polymorphonuclear leucocyte (PMN) chemotaxis.

METHODS

The chemotactic effect of tear and purified sIgA for PMN was studied using a modified Boyden chamber. Tears treated with anti-human IgA, complement-inactivated tears and albumin were used as controls.

RESULTS

The data indicate that both tear and purified sIgA are highly chemotactic for PMN. Anti-sIgA antibodies reduced the chemotactic effect of closed-eye tears (34%) and tear collected during ocular inflammation.

CONCLUSION

The massive recruitment of PMN in tears during sleep may be partially attributed to the increased levels of tear sIgA. This may play an important role in protecting the eye against bacterial infection.

The use of granulocyte-macrophage colony-stimulating factor to enhance hematologic parameters of patients with cirrhosis and hypersplenism

In patients with end-stage liver disease complicated with hypersplenism, neutropenia and thrombocytopenia are risk factors for systemic sepsis and spontaneous bleeding. Granulocyte-macrophage colony-stimulating factor is a naturally occurring cytokine that promotes proliferation and differentiation of granulocyte and monocyte progeny cells. In addition, it is reported to promote the proliferation of megakaryocytes. Its use as an intravenous infusion is Federal Drug Authority (USA) approved for the enhancement of myeloid recovery following autologous bone-marrow transplantation. The present study was initiated to determine whether granulocyte-macrophage colony-stimulating factor could be used to increase the white blood cell and platelet count in patients with cirrhosis and hypersplenism and to determine whether the more convenient subcutaneous route can be used with the same efficacy as the recommended intravenous route. Nine patients with cirrhosis and hypersplenism manifested by a reduced absolute neutrophil count (mean value of 1300 +/- 200/mm3) were studied. In eight patients, Indium white blood cell splenic sequestration scans were obtained before and after the administration of granulocyte-macrophage colony-stimulating factor intravenous infusion or subcutaneously for 7 days. One patient had to discontinue the therapy due to a reaction to granulocyte-macrophage colony-stimulating factor. Following intravenous infusion of granulocyte-macrophage colony-stimulating factor, the mean absolute neutrophil count increased to 2600 +/- 1100/mm3. Following subcutaneous administration, the mean absolute neutrophil count increased to 4100 +/- 200/mm3. No significant change in platelet count occurred with either route of administration. Indium scans obtained before and after the treatment period revealed no significant difference in the splenic uptake.(ABSTRACT TRUNCATED AT 250 WORDS)