Immersion fixed human peripheral blood lymphocytes
Measured by its ability to neutralize IL‑3-induced proliferation in the TF‑1 human erythroleukemic cell line. Kitamura, T. et al. (1989) J. Cell Physiol. 140:323. The Neutralization Dose (ND50) is typically 0.4-2 µg/mL in the presence of 1.25 ng/mL Recombinant Human IL‑3.
Please Note: Optimal dilutions should be determined by each laboratory for each application. General Protocols are available in the Technical Information section on our website.
Cell Proliferation Induced by IL‑3 and Neutralization by Human IL‑3 Antibody. Recombinant Human IL‑3 (Catalog # 203-IL) stimulates proliferation in the TF‑1 human erythroleukemic cell line in a dose-dependent manner (orange line). Proliferation elicited by Recombinant Human IL‑3 (1.25 ng/mL) is neutralized (green line) by increasing concentrations of Goat Anti-Human IL‑3 Polyclonal Antibody (Catalog # AB-203-NA). The ND50 is typically 0.4‑2 µg/mL.
Preparation and Storage
Reconstitute at 1 mg/mL in sterile PBS.
The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage
Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
12 months from date of receipt, -20 to -70 °C as supplied.
1 month, 2 to 8 °C under sterile conditions after reconstitution.
6 months, -20 to -70 °C under sterile conditions after reconstitution.
LAG-3 (Lymphocyte activation gene-3), also known as CD223, is a member of the immunoglobulin superfamily (IgSF). The mature LAG-3 protein is a 496 amino acid (aa) membrane protein with a 421 aa extracellular region which contains four IgSF domains, a 21 aa transmembrane region and a 54 aa cytoplasmic region. LAG-3 and CD4 molecules share <20% aa sequence homology but have a similar structure (1, 2). Both molecules bind to MHC class II. LAG-3 binds to MHC class II with higher affinity compared to CD4. Both LAG-3 and CD4 genes are located on the distal part of the short arm of chromosome 12.
LAG-3 is an activation-induced molecule, expressed on activated T cells and NK cells, but not on resting T cells. Studies using LAG-3 -/- mice have shown significant delay of T cell apoptosis following antigen stimulation and increased size of memory T cells pool following infection (3, 4). It also has been reported that anti-LAG-3 antibodies up-regulate T cell activation by blocking interaction of LAG-3 and MHC class II. The study has demonstrated that LAG-3 is selectively expressed on activated CD4+CD25+ TReg cells and plays a role in their suppressive activity (5). This evidence indicated, unlike the interaction of CD4 with MHC class II that plays a positive role in T cell activation, LAG-3 binds to MHC class II and negatively regulates T cell activation through LAG-3 signaling. On the other hand, studies have shown that binding of LAG-3 to MHC class II molecules on antigen presenting cells induce maturation of dendritic cells and cytokine secretion by monocytes through MHC class II signal transduction (6). Taken together, LAG-3 may have two major functions, it negatively regulates T cells activation through LAG-3 signaling and stimulates antigen presenting cells which express MHC class II.
Triebel, F. et al. (1990) J. Exp. Med. 171:1393.
Baixeras, E. et al. (1992) J. Exp. Med 176:327.
Workman, C.J. and D.A. Vignali (2003) Eur. J. Immunol. 33:970.
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