Peripheral blood contains two major particular infrequent dendritic cells (DC) subsets linking the innate and specific immune system, the myeloid DC and plasmacytoid DC equivalent to the natural interferon-producing cells (NIPC). The functional characterization of these cells demands large volumes of blood, making a large animal model more appropriate and beneficial for certain studies. Here, two subsets of porcine blood mononuclear cells expressing swine workshop cluster 3 (SWC3, a SIRP family member), are described and compared to monocytes. The blood DC specialized in T-cell stimulation were major histocompatibility complex (MHC) class II+, CD80/86+, CD1+/-, CD4-, and in contrast to monocytes CD14-. A CD16- and a CD16+ subset could be discriminated. Granulocyte-macrophage colony-stimulating factor and interleukin-3 were survival factors for this DC subset, and culture induced an up-regulation of MHC class II and CD80/86. The second subset described, are porcine NIPC, typically CD4++, MHC class IIlow, CD80/86low, CD1-, CD8-/low, CD16-/low and CD45RA-/low. Porcine NIPC had high interleukin-3 binding capacity, and survived in response to this cytokine. Their unique function was strong interferon type I secretion after virus stimulation. Both subsets were endocytically active when freshly isolated, and down-regulated this activity after in vitro maturation. Taken together, the present report has delineated porcine blood DC and NIPC, permitting a more detailed understanding of innate immune defences, particularly in response to infections.

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Background Specificities for carbohydrate IgG antibodies, thought to be predominantly of the IgG2 subclass, have never been broadly examined in healthy human subjects. Objective To examine commercial intravenous immunoglobulin (IVIg) preparations for their ability to recognize a wide range of glycans and to determine the contribution of IgG2 to the binding pattern observed. Methods We employed a glycan microarray to evaluate IVIg preparations and a control mix of similar proportions of human myeloma IgG1 and IgG2 for binding to 377 glycans courtesy of the Consortium for Functional Glycomics Core H (http://www.functionalglycomics.org/static/consortium/resources/resourcecoreh8.shtml). Glycans recognized were categorized using public databases for their likely cellular sources. IgG2 was depleted from IVIg using immunoaffinity chromatography and depletion confirmed using nephelometry and surface plasmon resonance. Results Nearly half of the glycans bound IgG. Some of the glycans with the greatest antibody binding can be found in structures of human pathogenic bacteria (e.g., Streptococcus pneumoniae, Mycobacterium tuberculosis, Vibrio cholera) and non-pathogenic bacteria, including lipopolysaccharide and lipoteichoic acid, capsular polysaccharides and exopolysaccharides. Surprisingly, depletion of IgG2 had only a modest effect on anti-carbohydrate recognition patterns compared to the starting IVIg preparation. Little to no binding activity was detected to human endogenous glycans including tumor-associated antigens. Conclusions This novel, comprehensive analysis provides evidence that IVIg contains a much wider range than previously appreciated of anti-carbohydrate IgG antibodies, including those recognizing both pathogenic and non-pathogen-associated prokaryotic glycans.

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