54.51/56.98 kDa (mature/pro-form) calculated.

Lymphocyte activation gene 3 protein (UniProt Q61790; also known as CD223, LAG-3) is encoded by the Lag3 gene (Gene ID 16768) in murine species. LAG-3 is an inhibitory T-cell surface molecule that modulates T-cell activation and homeostasis. LAG-3 co-localizes with CD8 and CD4 upon TCR engagement and alters TCR signaling. LAG-3 suppresses homeostasis proliferation (HP) of both lymphocytes and some dendritic cell populations in vivo, and enhanced HP is observed in mice deficient in LAG-3. LAG-3 signaling is shown to negatively regulate STAT5 phosphorylation in activated T cells, and no enhancement of HP was seen upon LAG-3 blockade in mice deficient in both STAT5a and STAT5b. Murine LAG-3 is produced with a signal peptide sequence (a.a. 1-22), the removal of which yields the mature protein with a large extracellular region (a.a. 23-442), followed by a transmembrane segment (a.a. 443-463) and a cytoplasmic tail (a.a. 464-521). The extracellular portion contains a V-type Ig-like domain (a.a. 37-163), followed by three C2-type Ig-like domains (a.a. 165-246, 258-341, and 345-412) and elven tandem repeats of 2-amino acid E-X seqeunce at its C-terminal end (a.a. 493-518).

Epitope: Within D3/D4 domains.

Murine LAG-3-expressing mouse T-cell hybridoma.

Flow Cytometry Analysis: 2.5 µg/mL from a representative lot detected surface LAG-3 immunoreactivity among the CD4+ and CD8+ populations of wild-type, but not Lag3-knockout, mouse splenocytes activated in vitro via CD3 cross-linking (Courtesy of Dario A. Vignali, Ph.D., University of Pittsburgh, PA, U.S.A.).
Flow Cytometry Analysis: A representative lot was fluorescently conjugated and detected an increased number of LAG-3-positive cells within the CD4+ and CD8+ populations of infiltrating lymphocytes (TILs) in tumors developed in mice exografted with murine B16 melanoma, MC38 colon adenocarcinoma, or Sa1N fibrosarcoma cells (Woo, S.R., et al. (2012). Cancer Res. 72(4): 917–927).
Flow Cytometry Analysis: A representative lot, pre-conjugated with Alexa Fluor^™ 647, detected both surface and intracellular LAG-3 by immunofluorescent staining of non-permeabilized and permeabilized primary murine CD4+ T cells activated in vitro via CD3 & CD28 cross-linking by immobilized antibodies. Pronase treatment of cells prior to permeabilization abolished cell surface staining (Woo, S.R., et al. (2010). Eur. J. Immunol. 40(6):1768-1777).
Flow Cytometry Analysis: A representative lot, pre-conjugated with Alexa Fluor 647, detected a time-dependent recovery of cell surface LAG-3 immunoreactivity on activated murine CD4+ T cells after initial surface LAG-3 degradation by pronase treatment. Protein synthesis inhibitor cycloheximide (Cat. No. 239764) or protein transport inhibitor Brefeldin A (Cat. No. 203729) treatment partially blocked the recovery (Woo, S.R., et al. (2010). Eur. J. Immunol. 40(6):1768-1777).
Immunocytochemistry Analysis: A representative lot detected both surface and intracellular LAG-3 by fluorescent immunocytochemistry staining of non-permeabilized and permeabilized primary murine CD4+ T cells activated in vitro via CD3 & CD28 cross-linking by immobilized antibodies. Pronase treatment of cells prior to permeabilization abolished cell surface staining (Woo, S.R., et al. (2010). Eur. J. Immunol. 40(6):1768-1777).
Immunocytochemistry Analysis: A representative lot detected intracellular LAG-3 immunoreactivity co-localized with those of the early and recycling endosome marker EEA1, as well as endosomal markers Rab11b and Rab27a by fluorescent immunocytochemistry staining of activated murine CD4+ T cells following pronase treatment and permeabilization (Woo, S.R., et al. (2010). Eur. J. Immunol. 40(6):1768-1777).

This Anti-LAG3 Antibody, clone 4-10-C9 is validated for use in Flow Cytometry, Immunocytochemistry for the detection of LAG3.

Clone 4-10-C9 immunostained surface LAG-3 on activated CD4+ T cells by targeting an extracellular epitope within the third and fourth Ig-like domains (D3/D4 domains; second and third C2-type Ig-like domains). Surface LAG-3 degradation by pronase treatment abolished cell surface staining (Woo, S.R., et al. (2010). Eur. J. Immunol. 40(6):1768-1777).

Format: Purified

Evaluated by Flow Cytometry in mouse splenocytes.

Flow Cytometry Analysis: 1 µg/mL of this antibody detected an induction of LAG-3-positive population in isolated mouse splenocytes following a 3-day 2 µg/mL Concanavalin A (Con A) stimulation.

ALEXA FLUOR is a trademark of Life Technologies