Anti-Mouse CD223 (LAG-3) [Clone C9B7W] — Purified in vivo PLATINUM™ Functional Grade

Clone C9B7W is extensively used in in vivo mouse studies to block the function of LAG-3 (CD223), a key immune checkpoint molecule that negatively regulates T cell activation and proliferation. Its most common in vivo applications include:

• Immune checkpoint blockade in tumor models:
  C9B7W is widely used to inhibit LAG-3 function in syngeneic tumor models (such as MC38 colorectal cancer, B16 melanoma, and others), often alone or in combination with other checkpoint inhibitors like anti-PD-1 antibodies, to assess effects on tumor growth, T cell function, and immune response.

• Functional studies of T cell regulation:
  Researchers use C9B7W to investigate how LAG-3 influences T cell expansion, homeostasis, and regulatory T cell (Treg) suppressive capacity in vivo, particularly focusing on its roles in autoimmunity and infectious disease models.

• Blocking LAG-3 in infectious disease and autoimmunity models:
  The antibody is used to study the impact of LAG-3 blockade on immune responses during chronic viral infections, or in models of autoimmune disease, to understand LAG-3's regulatory functions.

Mechanism:
C9B7W blocks LAG-3 function (preventing its inhibitory signaling in T cells), but notably does not block LAG-3's binding to MHC class II. This specificity allows analysis of LAG-3’s role in immune regulation independent of its ligand binding to MHC II.

Key Notes:

• C9B7W is also used in combination immunotherapy studies, testing for synergistic effects with other checkpoint inhibitors.
• For most applications, the antibody is administered systemically (e.g., intraperitoneally) at doses and regimens empirically determined based on the model.
• Variants with different Fc regions (e.g., Fc-mutated to reduce effector function) and chimeric versions exist to fine-tune immunomodulation in vivo.

Summary Table: Key In Vivo Uses of C9B7W in Mice

C9B7W is a standard tool in mouse immunology for dissecting the role of LAG-3 in diverse disease settings.

Based on the available literature, the C9B7W antibody (anti-mouse LAG-3/CD223) is commonly used in combination with or alongside several other antibodies and proteins in research studies:

Immune Checkpoint Antibodies

The C9B7W antibody is frequently combined with anti-PD-1 antibodies in studies investigating dual checkpoint blockade strategies. This combination approach examines how blocking both LAG-3 and PD-1 pathways can enhance anti-tumor immunity and therapeutic efficacy.

T Cell Activation Antibodies

In functional assays, C9B7W is often used with anti-CD3 and anti-CD28 antibodies to stimulate T cell activation. These antibodies are essential tools for studying LAG-3 expression and function on activated T cells, as LAG-3 is an activation-induced surface molecule.

Detection and Characterization Tools

For experimental detection and validation purposes, polyclonal anti-mouse CD223 antibodies are used alongside C9B7W, particularly in ELISA assays where C9B7W serves as the capture antibody and polyclonal antibodies function as detection antibodies.

MHC Class II Molecules

C9B7W is extensively studied in the context of its interaction with MHC class II molecules, including MHC-II tetramers (such as OVA-MHC-II-IA^b^ tetramers). These tetramers are used to assess whether C9B7W blocks the binding of LAG-3 to MHC class II, which is LAG-3's natural ligand.

Surface Markers for T Cell Subsets

Researchers commonly examine C9B7W-stained cells alongside other markers like CD4, CD8, CD25, and CD49b to identify specific T cell populations, including regulatory T cells and Type 1 regulatory T cells.

Clone C9B7W is a widely used rat monoclonal antibody targeting mouse LAG-3 (CD223). The key findings from scientific literature citations of this clone are:

• Epitope specificity: C9B7W binds specifically to an epitope within the D2 domain of mouse LAG-3.

• Mechanism of action: The primary mechanism by which C9B7W inhibits LAG-3 function is by disrupting LAG-3 dimerization. This disruption impairs LAG-3’s association with the TCR/CD3 complex, thereby attenuating its inhibitory effect on T cell activation.

• Function in blocking assays: Although C9B7W is often referred to as a "blocking" antibody, it does not directly block the binding of LAG-3 to its canonical ligand, MHC class II. Instead, C9B7W induces conformational changes in LAG-3 that weakly attenuate ligand interaction, primarily via effects on protein structure and dimerization.

• Functional impact: C9B7W enhances T cell proliferation and effector functions by inhibiting LAG-3’s suppressive activity. In various assays, this has been shown to result in increased immune activation and anti-tumor responses.

• Cellular consequences: In physiological assays, C9B7W potently inhibits LAG-3-mediated signaling, blocking both MHCII- and FGL1-mediated inhibitory signals through LAG-3 CAR systems. It can also prevent LAG-3 migration into the immunological synapse (IS).

• Research applications: C9B7W is validated for use in flow cytometry, functional assays, and in vivo studies for both basic immunological research and therapeutic investigations.

Summary Table: Main Properties and Findings of C9B7W

In sum, C9B7W is a D2-specific monoclonal antibody that disrupts LAG-3 dimerization and function, resulting in inhibition of immune checkpoint activity, but does not directly block MHC class II binding. These properties underpin its widespread use in mouse immunology for mechanistic studies and therapeutic testing.

Dosing regimens for the C9B7W clone, which targets mouse CD223 (LAG-3), can vary significantly across different mouse models. The specific dosing details, including the amount, frequency, and route of administration, are often tailored to the experimental context and the particular mouse model being used.

Key Considerations:

• Customization: Researchers typically customize the dose, route, and frequency according to the specific experimental needs and the mouse model involved.
• Lack of Standardization: There is no standard dosing regimen for C9B7W across all mouse models; instead, it is adjusted based on the study's objectives and the biological characteristics of the model.
• Experimental Context: The choice of dosing is influenced by factors such as the tumor type, immune response goals, and whether the antibody is used alone or in combination with other treatments.

Examples of Variability:

• In some studies, the focus might be on blocking LAG-3 function to modulate T cell responses, requiring specific dosing strategies to achieve the desired immune modulation.
• Other studies may explore the combination of C9B7W with other checkpoint inhibitors to enhance antitumor effects, which could influence dosing decisions.

Overall, the dosing regimens for clone C9B7W are highly adaptable and depend on the specific research goals and the characteristics of the mouse model being studied.