Investigating Immune Gene Signatures in Peripheral Blood from Subjects with Allergic Rhinitis Undergoing Nasal Allergen Challenge.

Nasal allergen challenge (NAC) is a human model of allergic rhinitis (AR) that delivers standardized allergens locally to the nasal mucosa allowing clinical symptoms and biospecimens such as peripheral blood to be collected. Although many studies have focused on local inflammatory sites, peripheral blood, an important mediator and a component of the systemic immune response, has not been well studied in the setting of AR. We sought to investigate immune gene signatures in peripheral blood collected after NAC under the setting of AR. Clinical symptoms and peripheral blood samples from AR subjects were collected during NAC. Fuzzy c-means clustering method was used to identify immune gene expression patterns in blood over time points (before NAC and 1, 2, and 6 h after NAC). We identified and validated seven clusters of differentially expressed immune genes after NAC onset. Clusters 2, 3, and 4 were associated with neutrophil and lymphocyte frequencies and neutrophil/lymphocyte ratio after the allergen challenge. The patterns of the clusters and immune cell frequencies were associated with the clinical symptoms of the AR subjects and were significantly different from healthy nonallergic subjects who had also undergone NAC. Our approach identified dynamic signatures of immune gene expression in blood as a systemic immune response associated with clinical symptoms after NAC. The immune gene signatures may allow cross-sectional investigation of the pathophysiology of AR and may also be useful as a potential objective measurement for diagnosis and treatment of AR combined with the NAC model.

In vitro cytokine release assays: reducing the risk of adverse events in man.

The induction of cytokine release is a common consequence of the administration of therapeutic antibodies and in most cases is either tolerated by the patient or can be managed clinically by the administration of corticosteroids. However, in 2006, the administration of TGN1412 to six patients in a Phase I trial resulted in a unprecedentedly high level of cytokine release, systemic organ failure and the hospitalization of the subjects. Whilst the path to failure in this incident was multifactorial, at least one contributing factor was the lack of a robust in vitro model that would allow the prediction of the in vivo activity of a therapeutic antibody. In this article we review the current 'state of the art' of in vitro cytokine release assays and explore potential future developments.

CD26 is expressed on a restricted subpopulation of dendritic cells in vivo.

Two major sub-populations of dendritic cells (DC) are present in afferent lymph draining the skin of cattle distinguished by expression of signal regulator protein alpha (SIRPalpha). The SIRPalpha(-) population expresses the uncharacterized bovine WC10 antigen (Ag). Initial N-terminal sequencing of the WC10 protein purified by affinity chromatography showed significant homology with human CD26. A cDNA encoding bovine CD26 was cloned and the recombinant molecule expressed in COS-7 cells. Transfectants abrogated the ability of macrophage-derived chemokine (MDC) to cause a calcium flux in bovine PBMC indicating enzymatic activity characteristic of CD26. They also stained with WC10 monoclonal antibody confirming that the Ag is CD26. This is the first description of CD26 expression by DC in vivo or in vitro. It is expressed on a sub-population of ex vivo DC in afferent lymph draining the skin and on sub-populations of DC isolated from prescapular and mesenteric lymph nodes draining the skin or intestine, respectively. CD26 is an exopeptidase with specificity for motifs within the receptor-binding domain of several chemokines including MDC. CD26 mediated truncation of MDC affects the Th cell response effected by the chemokine and may produce a Th1 bias. Transcripts for MDC were present in both CD26(+) and CD26(-) DC, thus CD26 mediated modification of MDC may bias the immune response induced in naive T cells by DC.

DEC-205 expression on migrating dendritic cells in afferent lymph.

Previous studies have identified a 210 000-molecular weight molecule expressed at a high level on the surface of dendritic cells (DCs) in afferent lymph of cattle and evident on cells with the morphology of DCs in lymphoid tissues. Expression is either absent from other immune cells or is present at a lower level. The molecular weight and cellular distribution suggested that the molecule, called bovine WC6 antigen (workshop cluster), might be an orthologue of human DEC-205 (CD205). To establish whether this was the case, the open reading frame of bovine DEC-205 was amplified, by polymerase chain reaction, from thymic cDNA (accession no. AY264845). The cDNA sequence of bovine DEC-205 had 86% and 78% nucleic acid identity with human and mouse molecules, respectively. COS-7 cells transfected with a plasmid containing the cattle DEC-205 coding region expressed a molecule that stained with WC6-specific monoclonal antibody, showing that ruminant WC6 is an orthologue of DEC-205. Two-colour flow cytometry of mononuclear cells from afferent lymph draining cattle skin, and from blood, confirmed the high level of expression on large cells in lymph that were uniformly DC-LAMP positive and major histocompatibility complex class II positive. Within this DEC-205+ DC-LAMP+ population were subpopulations of cells that expressed the mannose receptor or SIRPalpha. The observations imply that DCs in afferent lymph are all DEC-205high, but not a uniform population of homogeneous mature DCs.