Mouse monoclonal / IgG 1:100 – 1:200 Research Use Only Cytoplasmic and cell surface. Human MSVA-955M Allograft inflammatory factor 1 (AIF1); balloon angioplasty responsive transcription (BART1); IBA1; Interferon responsive transcript 1; Ionized calcium-binding adapter molecule 1; IRT1; Microglia response factor (MRF1) Colon: An at least moderate to strong cytoplasmic AIF1 immunostaining should be seen in mucosal macrophages. Colon: AIF1 immunostaining should be absent in all non-inflammatory cells. AIF1 is a putative marker for macrophage activation status. Allograft inflammatory factor 1 (AIF1) is coded by the AIF1 gene at 6p21.3 where it is located within the major histocompatibility complex class III region known to harbor clusters of genes involved in inflammatory responses. AIF1 is a phylogenetically conserved gene. Three isoforms exist, the largest of which, AIF1 splice variant 3 (AIF1v3), has a molecular mass of 17 kDa. The function of AIF1 is not well known. The protein is upregulated in activated macrophages and neutrophils in response to the cytokine IFN-γ. AIF1 impacts the expression of several important mediators such as cytokines, chemokines and inducible nitric oxide synthase. It is involved in inflammatory responses, auto-immune diseases, reproductive immunity as well as immune activation and macrophage function. AIF1 may also regulate several important cell adhesion molecules. Increased AIF1 expression levels have been found in cancers and AIF1 has been suggested to have a significant role in cancer progression. AIF1 immunostaining is seen at varying levels of intensity in histiocytes/macrophages in various different tissues. The staining is mostly moderate to strong but varies depending on the location of cells and also between different samples from identical tissues. For example, AIF1 immunostaining is considerably weaker in dendritic cells/macrophages of the germinal centre than in macrophages of the interfollicular area in lymph nodes and tonsils. AIF1 expression can be particularly strong in Kupffer cells in the liver, placenta macrophages (variable between samples), lung, and the adrenal gland. In the brain, a variable staining of microglia occurs, ranging from low to high intensity. Granulocytes also stain AIF1 positive. In the kidney, a moderate to strong membranous staining of glomeruli is seen. This reflects the only AIF1 staining of non-immunological cells in normal adult tissues. These findings are largely consistent with the RNA and protein data described in the Human Protein Atl... A positive AIF1 immunostaining of inflammatory cells is invariably seen in tumors. The quantity of positive cells and also the staining intensity of positive cells is highly variable, however. There is no evidence of AIF1 production in epithelial tumor cells so far. TCGA data suggest, that a high level of AIF1 RNA expression may be linked to unfavorable disease course in kidney cancer. The TCGA findings on AIF1 RNA expression in different tumor categories have been summarized in the Human Protein Atlas. Pulmonary adenocarcinoma displaying abundant AIF1 positive inflammatory cells. Hodgkin’s lymphoma almost completely consisting of AIF1 positive inflammatory cells. Note: Hodgkin’s and Reed Sternberg cells are AIF1 negative. Sarcoma NOS containing abundant AIF1 positive inflammatory cells. Cancer tissue gallery No data available at the moment IHC users have different preferences on how the stains should look like. Some prefer high staining intensity of the target stain and even accept some background. Others favor absolute specificity and lighter target stains. Factors that invariably lead to more intense staining include higher concentration of the antibody and visualization tools, longer incubation time, higher temperature during incubation, higher temperature and longer duration of the heat induced epitope retrieval (slide pretreatment). The impact of the pH during slide pretreatment has variable effects and depends on the antibody and the target protein. All images and data shown here and in our image galleries are obtained by the manual protocol described below. Other protocols resulting in equivalent staining are described as well. Manual protocol Freshly cut sections should be used (less than 10 days between cutting and staining). Heat-induced antigen retrieval for 5 minutes in an autoclave at 121°C in pH 7,8 Target ... AIF1 expression may represent a marker for the activity of macrophages. In general, AIF1 plays an important but largely unknown role in immunology. AIF1 is thus an important research target. There are two ways how the specificity of an antibody can be documented for the application “immunohistochemistry on formalin fixed tissues”. These are: 1. comparison with a second independent method for target expression measurement across a large number of different tissue types (orthogonal strategy), and 2. Comparison with one or several independent antibodies for the same target and showing that all positive staining results are also seen with other antibodies for the same target (independent antibody strategy). Both methods were applied for MSVA- 955M . Orthogonal validation: For the antibody MSVA- 955M , specificity is supported by the RNA expression data derived from three independent RNA screening studies, including the Human Protein Atlas (HPA) RNA-seq tissue dataset, the FANTOM5 project, and the Genotype-Tissue Expression (GTEx) project, which are all summarized in the Human Protein Atlas (Tissue expression AIF1) . These databases describe a very high expression in lymphatic ...
