Inducible T-cell costimulator (UniProt Q9WVS0; also known as Activation-inducible lymphocyte immunomediatory molecule, CCLP, CD278, CD28 and CTLA-4-like protein, CD28-related protein 1, CRP-1, H4) is encoded by the Icos (also known as Ailim) gene (Gene ID 54167) in murine species. ICOS is a costimulatory molecule expressed on activated T cells and regulatory T cells, it plays a crucial role in T-cell survival and function, Th2 cell differentiation, and lung inflammatory responses. Upon ICOS-ligand (ICOS-L) binding, ICOS initiates a cascade of intracellular signaling events, leading to the production of cytokines such as IL-4 and IL-13. Both ICOS and ICOS-L are expressed on type 2 innate lymphoid cells (ILC2s) that, along with Th2 cells, contribute to the pathogenesis of asthma by producing copious amounts of IL-5 and IL-13. ICOS and ICOS-L interaction is reported to promote cytokine production and survival of ILC2s through STAT5 signaling. ICOS-deficiency or blocking ICOS and ICOS-L interaction is shown to prevent cytokine-induced asthma and lung inflammation in a humanized murine model with adoptively transferred human peripheral ILC2s. Human and murine ICOS proteins are produced with a signal peptide (a.a. 1-20) sequence, which is removed posttranslationally to yield the mature protein with a large N-terminal extracellular (human a.a. 21-140 and murine a.a. 21-144) region composed almost entirely of a V-type Ig-like domain (human a.a. 30-132 and murine a.a. 30-133), followed by a transmembrane domain (human a.a. 141-161 and murine a.a. 145-165) and a cytoplasmic tail (human a.a. 162-199 and murine a.a. 166-200).
Clone C398.4A recognizes a extracellular epitope present in murine (UniProt Q9WVS0) and the two alternatively spliced human ICOS/CD278 isoforms (UniProt Q9Y6W8).
D10.G4.1 murine TH2 cells (Redoglia, V., et al. (1996). Eur. J. Immunol. 26(11):2781-2789).
Epitope: extracellular domain
Affects Function: A representative lot increased the proliferation of D10.G4.1 murine TH2 cells and freshly isolated murine spleen T cells induced by clonotypic TCR mAb, by TCR Cbeta mAb, by CD3 mAb 2C11 or by Con A. No proliferation was induced by C398.4A mAb alone (Redoglia, V., et al. (1996). Eur. J. Immunol. 26(11):2781-2789).
Flow Cytometry Analysis: A representative lot detected the surface expression of exogenously transfected human ICOS on the surface of murine L cell fibroblasts. Clone C398.4A and another ICOS mAb (clone F44) competed against each other for the the suface staining of PHA-activated human peripheral blood T-cells (Buonfiglio, D., et al. (2000). Eur. J. Immunol. 30(12):3463-3467).
Flow Cytometry Analysis: A representative lot detected a greatly enhanced ICOS/CD278- (hpH4; human putative mouse H4 homolog) positive cell population among isolated human PBMCs following PHA stimulation (Buonfiglio, D., et al. (1999). Eur. J. Immunol. 29(9):2863-2874).
Flow Cytometry Analysis: A representative lot immunostained D10.G4.1 murine TH2 cells as well as activated, but not resting, T and B cells freshly isolated from mouse spleen (Redoglia, V., et al. (1996). Eur. J. Immunol. 26(11):2781-2789).
Immunocytochemistry Analysis: A representative lot immunostained H4 (ICOS/CD278) immunoreactivity co-capped with that of TCR mAb 3D3 on the surface of D10.G4.1 murine TH2 cells by immunofluorescence microscopy (Redoglia, V., et al. (1996). Eur. J. Immunol. 26(11):2781-2789).
Immunohistochemistry Analysis: A representative lot immunostained the membrane of hpH4- (ICOS/CD278) positive lymphocytes in acetone-fixed frozen human reactive lymph node sections, while most neoplastic cells showed cytoplasmic hpH4 staining in frozen PTCL-U (peripheral T cell lymphoma, unspecified) and angioimmunoblastic T cell lymphoma sections (Buonfiglio, D., et al. (1999). Eur. J. Immunol. 29(9):2863-2874).
Immunoprecipitation Analysis: A representative lot immunoprecipitated and depleted ICOS from human T-cell lymphoma HuT 78 cell lysates (Buonfiglio, D., et al. (2000). Eur. J. Immunol. 30(12):3463-3467).
Immunoprecipitation Analysis: A representative lot immunoprecipitated H4 (ICOS/CD278) from PHA-activiated human peripheral blood (PB) T cells in a ~55-70 kDa glycosylated dimeric form (Buonfiglio, D., et al. (1999). Eur. J. Immunol. 29(9):2863-2874).
Immunoprecipitation Analysis: A representative lot immunoprecipitated H4 (ICOS/CD278) from D10.G4.1 murine TH2 cells in a glycosylated dimeric form (Redoglia, V., et al. (1996). Eur. J. Immunol. 26(11):2781-2789).
Inflammation & Immunology
This armenian hamster monoclonal Anti-ICOS/CD278 Antibody, clone C398.4A, Cat. No. MABF977 is validated for use in Flow Cytometry, Function Assay, Immunocytochemistry, Immunohistochemistry, and Immunoprecipitation for the detection of ICOS.
Evaluated by Flow Cytometry in PHA stimulated PBMCs cells.
Flow Cytometry Analysis: 0.1 µg of this antibody detected ICOS/CD278 immunoreactivity on the surface of PHA-activated (5 µg/mL at 37°C for 72 hours) human PBMCs.
20.27/22.71 kDa (mouse mature/pro-form) and 20.22 /22.63 kDa (human isoform 1 mature/pro-form), 16.72/19.13 kDa (human isoform 2 mature/pro-form) calcualted. ~55-70 kDa (dimer). ~29 and 37 kDa (monomer), ~20-21 kDa (deglycosylated monomer) reported (Buonfiglio, D., et al. (1999). Eur. J. Immunol. 29(9):2863-2874).
Protein G purified.
Purified Armenian hamster monoclonal antibody IgG in PBS without preservatives.
Storage and Stability
Stable for 1 year at -20°C from date of receipt.
Handling Recommendations: Upon receipt and prior to removing the cap, centrifuge the vial and gently mix the solution. Aliquot into microcentrifuge tubes and store at -20°C. Avoid repeated freeze/thaw cycles, which may damage IgG and affect product performance.
Concentration: Please refer to lot specific datasheet.
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