Characterization of human leucocytes bearing the IL-3 receptor

Class C CpG Oligodeoxynucleotide Immunomodulatory Response in Aged Squirrel Monkey (Saimiri Boliviensis Boliviensis)

One means of stimulating the mammalian innate immune system is via Toll-like receptor 9 (TLR9) being exposed to unmethylated cytosine-phosphate-guanine (CpG) DNA, also known as pathogen-associated molecular patterns (PAMPs) of microbial origin. Synthetic CpG oligodeoxynucleotides (ODNs) with defined CpG motifs possess broad immunostimulatory properties that make CpG ODNs suitable as therapeutic interventions in a variety of human disease conditions, including Alzheimer's disease (AD). Rodent models are often used to preclinically test the effectiveness of CpG ODN therapeutic agents for AD and other disorders. However, the translatability of findings in such models is limited due to the significant difference of the expression of TLR9 between primates and rodents. The squirrel monkey (SQM), a New World non-human primate (NHP), is known to be phylogenetically proximate to humans, and develops extensive age-dependent cerebral amyloid angiopathy (CAA), a key pathological feature of AD. Hence, this model is currently being used to test AD therapeutics. In the present study, we conducted the first examination of Class C CpG ODN's immunomodulatory role in elderly SQMs. We documented the effectiveness of CpG ODN to trigger an immune response in an aged cohort whose immune system is senescent. The specific immune response patterns detected here closely resembled CpG ODN-induced immunostimulatory patterns observed in prior human studies. Overall, our findings provide critical data regarding the immunomodulatory potential of CpG ODN in this NHP model, allowing for future translational studies of innate immunity stimulation via TLR9 agonists for diverse indications, including AD therapeutics.

Impact of varicella-zoster virus on dendritic cell subsets in human skin during natural infection

Varicella-zoster virus (VZV) causes varicella and herpes zoster, diseases characterized by distinct cutaneous rashes. Dendritic cells (DC) are essential for inducing antiviral immune responses; however, the contribution of DC subsets to immune control during natural cutaneous VZV infection has not been investigated. Immunostaining showed that compared to normal skin, the proportion of cells expressing DC-SIGN (a dermal DC marker) or DC-LAMP and CD83 (mature DC markers) were not significantly altered in infected skin. In contrast, the frequency of Langerhans cells was significantly decreased in VZV-infected skin, whereas there was an influx of plasmacytoid DC, a potent secretor of type I interferon (IFN). Langerhans cells and plasmacytoid DC in infected skin were closely associated with VZV antigen-positive cells, and some Langerhans cells and plasmacytoid DC were VZV antigen positive. To extend these in vivo observations, both plasmacytoid DC (PDC) isolated from human blood and Langerhans cells derived from MUTZ-3 cells were shown to be permissive to VZV infection. In VZV-infected PDC cultures, significant induction of alpha IFN (IFN-alpha) did not occur, indicating the VZV inhibits the capacity of PDC to induce expression of this host defense cytokine. This study defines changes in the response of DC which occur during cutaneous VZV infection and implicates infection of DC subtypes in VZV pathogenesis.

Detection of cytokine receptors by flow cytometry

This unit describes three protocols for detecting cytokine receptors on human peripheral blood mononuclear cells or murine splenic lymphocytes via immunofluorescence labeling. The three protocols have in common the use of phycoerythrin as a highly effective fluorescent dye, multiple-layer staining to increase sensitivity, and selection of reagents for maximum sensitivity. The first procedure uses monoclonal antibody (MAb) against receptor protein, detected with biotinylated anti-Ig (directed against the species in which the MAb is made), which in turn is stained with phycoerythrin-streptavidin (PE-SA). The second procedure uses biotinylated cytokines in the first step, followed by PE-SA. Finally, a third procedure describes multiparameter analysis involving second and third fluorophores introduced as direct antibody conjugates, which is used to study subset expression of receptors. Instructions are also provided for titrating MAbs and cytokines, as well as how to evaluate detection reagents such as anti-Ig conjugates and fluorophores.

The effects of gene gun delivered pIL-3 adjuvant on skin pathology and cytokine expression

The aim of this study was to investigate skin immunopathology following gene gun delivery of plasmid-encoding interleukin 3 (pIL-3) and hence explore the possible mechanisms of its adjuvant activity. Using the sheep as the experimental model, expressible pIL-3 was administered to the epidermis and the dermal/epidermal junction and its effects on the skin were assessed by histopathology, immunohistology and quantitative RT-PCR for a range of pro-inflammatory and immune response polarizing cytokines. Delivery of both functional and non-functional plasmids caused an acute inflammatory response with the infiltration of neutrophils and micro-abscess formation; however, the response to pIL-3 was more severe and was also associated with an early (24 h) infiltration of B cells and a later accumulation of CD172a-/CD45RA+ dendritic cells (DC). In terms of cytokine transcript expression, an early TNFalpha response was stimulated by gene gun delivery of plasmid-associated gold beads, which coincided with an immediate infiltration of neutrophils. However, only pIL-3 triggered the short-lived expression of IL-3 (peaking at 6 h) and significant long-term increases in both TNFalpha and IL-1beta. pIL-3 did not affect the expression of the immune response polarizing cytokines, IL-10 and IL-12.

Invited review: Bovine milk fat globule membrane as a potential nutraceutical

For the last 15 yr, a great deal of knowledge has been accumulated on health beneficial factors, protein and nonprotein, of bovine milk fat globule membrane (MFGM). Among the health-beneficial components of the MFGM are cholesterolemia-lowering factor, inhibitors of cancer cell growth, vitamin binders, inhibitor of Helicobacter pylori, inhibitor of beta-glucuronidase of the intestinal Escherichia coli, xanthine oxidase as a bactericidal agent, butyrophilin as a possible suppressor of multiple sclerosis, and phospholipids as agents against colon cancer, gastrointestinal pathogens, Alzheimer's disease, depression, and stress. All of the above compel us to consider bovine MFGM as a potential nutraceutical.

The role of interleukin-3 in classical Hodgkin's disease

Classical Hodgkin's disease (HD) is a peculiar form of lymphoma characterized by a low frequency of tumor cells, the so-called Hodgkin (H) and Reed/Sternberg (RS) cells, embedded in a background of non-neoplastic (reactive) cells believed to be recruited and activated by H-RS cell-derived cytokines/chemokines. How these tumor cells can survive in such a seemingly hostile environment has confused researchers. We have previously identified interleukin (IL)-3 receptor (R) expression as a common feature of classical HD and unveiled the potential role of IL-3 as a growth and anti-apoptotic factor for H-RS cells. More then 90% of malignant cells of classical HD usually express the alpha chain of the IL-3R (IL-3R(alpha)), as evidenced by immunostaining of frozen sections and cell suspensions from neoplastic lymph nodes. Consistently, HD-derived cell lines (L428, KMH2, HDLM2 and L1236) express the alpha and beta chains that form IL-3R, both at the mRNA and protein level, with a molecular size of IL-3R(alpha) identical (70 kDa) to that expressed by human myeloid cells. Exogenous IL-3 promotes the growth of cultured H-RS cells, such an effect being potentiated by IL-9 and stem cell factor (SCF) co-stimulation, and is able to partially rescue tumor cells from apoptosis induced by serum deprivation. Finally, cultured H-RS cells are able to increase the production of IL-3 by pre-activated T cells, suggesting an involvement of IL-3/IL-3R interactions in the cellular growth of HD through paracrine mechanisms. This review will outline the biological activity of IL-3 and summarize the evidence indicating IL-3 as a growth and anti-apoptotic factor for H-RS cells in classical HD.

Expression of functional interleukin-3 receptors on Hodgkin and Reed-Sternberg cells

The human interleukin-3 receptor (IL-3R) is a heterodimeric complex consisting of an IL-3-specific alpha chain (IL-3Ralpha) and a common beta chain (beta(c)), this latter shared with the receptors for granulocyte-macrophage colony-stimulating factor and IL-5. Despite extensive research on cytokine circuitries regulating proliferation and survival of tumor cells in Hodgkin's disease (HD) the functional expression of IL-3Rs in this pathobiological entity has not yet been investigated. In the present study, we demonstrate that the great majority (>90%) of malignant Hodgkin and Reed-Sternberg cells of classic HD (19 of 19 analyzed cases) express IL-3Ralpha by immunostaining of frozen sections and cell suspensions from involved lymph nodes. Accordingly, HD cell lines (L428, KMH2, HDLM2, L1236) expressed the alpha and beta chains of IL-3R both at the mRNA and protein level, with a molecular size of IL-3Ralpha identical (70 kd) to that expressed by human myeloid cells. Exogenous IL-3 promoted the growth of cultured Hodgkin and Reed-Sternberg cells, such effect being potentiated by IL-9 co-stimulation, and was able to partially rescue tumor cells from apoptosis induced by serum deprivation. This data suggests an involvement of IL-3/IL-3R interactions in the cellular growth of HD through paracrine mechanisms.

Interleukin-3 and Flt3-ligand induce adhesion of Baf3/Flt3 precursor B-lymphoid cells to fibronectin via activation of VLA-4 and VLA-5

Adhesion of hematopoietic cells to extracellular matrix components is important for blood cell development. However, little is known regarding the potential influence of IL-3 on this process for precursor B cells and Flt3-ligand has not yet been implicated in induction of adhesion of any blood cell types to extracellular matrix components. Therefore, we examined the characteristics of cytokine-induced cell adhesion to fibronectin (FN), using as a model the murine precursor B cell line, Baf3, a factor-dependent cell line requiring IL-3 for both growth and survival. Since factor-dependent hematopoietic cell lines expressing Flt3 receptor are extremely rare, we also studied Baf3/Flt3, a subline of Baf3 transduced with the Flt3 receptor gene. IL-3 induced adhesion of Baf3 and Baf3/Flt3 cells to FN, while Flt3-ligand induced adhesion of Baf3/Flt3 cells only. Whereas both Baf3 and Baf3/Flt3 cells expressed VLA-4 and -5 integrins as FN receptors, expression levels of VLA-4 and -5 were not affected by IL-3 or Flt3-ligand treatment. However, blocking experiments using anti-integrin antibodies showed that cytokine-induced adhesion of cells depended on both VLA-4 and -5 suggesting that IL-3 and Flt3-ligand activated these integrins. PI-3 kinase inhibitor wortmannin, PKC inhibitor H-7, or PKA inhibitor HA1004 did not suppress adhesion induced by IL-3 or Flt3-ligand; in contrast, PLC inhibitor U-73122 did suppress adhesion, suggesting the possibility that PLC, but not PI-3 kinase, PKC, or PKA, may be involved in this process. Since it is known that IL-3 and Flt3-ligand receptors are expressed on precursor B cells, and these receptors are downregulated during B cell maturation of primary cells, the induction of precursor B cell adhesion to FN by IL-3 and Flt3-ligand may contribute a mechanism by which precursor B cells adhere to bone marrow stroma, thereby influencing their development.