Clone GK1.5 is most commonly used in vivo in mice for depletion of CD4+ T cells, enabling researchers to study the roles of these cells in immune responses, disease models, and therapeutic interventions. Additional in vivo applications include blocking CD4mediated cell functions to disrupt helper T cell interactions with MHC class II molecules and impair T cell activation.

Key in vivo applications of GK1.5 in mice:

• CD4+ T cell depletion: Systemic administration of GK1.5 efficiently and specifically eliminates CD4+ T cells, allowing for the investigation of their role in autoimmunity, infectious diseases, cancer, and transplantation.
• Functional blockade of CD4: GK1.5 is used to block helper T cell responses to MHC class II antigens, interrupting processes such as cytolysis, antigenspecific proliferation, cytokine secretion, and B cell help.
• Combination with other reagents: When used with additional monoclonal antibodies, GK1.5 enables multicolor immunophenotyping or selective depletion of other hematopoietic lineages, supporting adoptive transfer, immune reconstitution, or lineagetracking studies.

Experimental contexts where GK1.5 is extensively used in vivo:

• Autoimmune disease models: For example, reducing disease severity in arthritis by depleting CD4+ T cells.
• Infection research: Investigating the contribution of CD4+ T cells to immunity or pathogenesis, such as in murine models of viral infection.
• Cancer immunotherapy: Studying the effects of CD4+ T cell or regulatory T cell depletion on tumor growth and immune responses, sometimes in combination with other immunomodulatory antibodies.

GK1.5 is primarily chosen for its high specificity, efficiency in vivo, and welldocumented depletion kinetics in the mouse model. The antibody is available in forms and buffers designed specifically for in vivo work, ensuring low endotoxin and the absence of toxic preservatives.

In summary, in vivo depletion and functional blockade of CD4+ T cells represent the principal applications of GK1.5 in mice. These experimental strategies underpin research in immunology, infectious disease, oncology, and transplantation biology.

Other antibodies and proteins commonly used with GK1.5 (antimouse CD4) in the literature include antiCD8 (for cytotoxic T cells), antiCD3 (panT cell marker), antiCD25 (Treg marker), and various isotype controls. Below is a summary of typical pairings and markers observed in experimental setups:

• AntiCD8 (e.g., clone 536.7): Used to distinguish or sort CD8(^+) cytotoxic T cells versus the CD4(^+) population labeled by GK1.5.
• AntiCD3: PanT cell marker to identify all T cells (CD3 is present on both CD4(^+) and CD8(^+) T cells), frequently used in multicolor flow cytometry protocols alongside GK1.5.
• AntiCD25 (e.g., clone PC61): For identifying regulatory T cells (Tregs, CD4(^+)CD25(^+)), often paired in gating strategies.
• AntiFoxp3: Intracellular marker of Tregs, often stained together with GK1.5 and antiCD25.
• Isotype controls (rat IgG2b): Because GK1.5 is a rat IgG2b, appropriate isotypematched controls (like antiKLH, clone LTF2) are used to monitor for nonspecific staining.
• Live/dead cell discrimination dyes: Standard annotation in immunophenotyping panels using GK1.5 to exclude dead cells.

Supporting context:

• Other antiCD4 clones such as RM45 or RM44 may be included for competition or blocking studies, since RM45 can block GK1.5 binding.
• Additional T cell markers: AntiCD44 (activation/memory marker), antiCD62L (naïve/memory status), and antiCD45 (leukocyte common marker) are often part of larger multicolor panels with GK1.5.
• Dendritic cell/monocyte markers: Since CD4 can be expressed, albeit at lower levels, on dendritic cells and some monocytes, researchers often use antiCD11c or antiCD11b to phenotype other cell subsets in conjunction with GK1.5.

Typical panel configuration example:| Marker | Clone Example | Cell Subset/Function |||||| CD4 | GK1.5 | Helper T cells || CD8 | 536.7 | Cytotoxic T cells || CD3 | 1452C11 | PanT cells || CD25 | PC61 | Regulatory T cells || Foxp3 | FJK16s | Regulatory T cells (intracellular) || Isotype control | LTF2 | Nonspecific staining control || CD44, CD62L, CD45, etc. | Various | Memory/activation state || CD11b, CD11c | M1/70, N418 | Myeloid (monocytes, DCs) |

References to recommended controls and typical applications are given by multiple manufacturers and validated protocols. Most peerreviewed publications investigating mouse Tcell subsets or immune depletion strategies in vivo will use at least one of these in tandem with GK1.5.

Clone GK1.5, a monoclonal antibody targeting mouse CD4, is extensively used in scientific research for in vivo T cell depletion, particularly focusing on CD4+ T cells. Here are key findings and applications from scientific literature:

Key Uses and Findings

1. CD4+ T Cell Depletion: GK1.5 is primarily used for depleting CD4+ T cells in mice, allowing researchers to study the role of these cells in immune responses, disease progression, and therapeutic interventions.

2. Mechanism of Action: The antibody binds to the CD4 antigen, which acts as a coreceptor for T cell activation by interacting with class II MHC molecules on antigenpresenting cells. This interaction is crucial for T cell function and development.

3. Applications in Disease Models:

   • Autoimmune Diseases: Studies have shown that GK1.5mediated CD4+ T cell depletion can reduce disease severity in models of autoimmune diseases by modulating immune responses.
   • Infectious Diseases: GK1.5 has been used in models of HIV to reduce viral load and disease progression.
   • Cancer Immunotherapy: Depletion of CD4+ T cells using GK1.5 has been explored to enhance antitumor immunity by targeting regulatory T cells.

4. Specificity and Competition: GK1.5 competes with other clones like YTS 177 and YTS 191 for CD4 binding, highlighting its specificity for CD4+ T cell targeting.

5. Dosage and Considerations: The optimal dose of GK1.5 varies, typically ranging from 50 to 500 μg per injection. Careful optimization is necessary to ensure efficacy and minimize offtarget effects.

6. Comparative Studies: Other clones such as YTS 191.1 are used as alternatives in mouse models, while W3/25 is used in rat models and OKT4A in nonhuman primates.

Conclusion

Clone GK1.5 is a valuable tool in immunological research, enabling precise depletion of CD4+ T cells to understand their roles in health and disease. Its applications span various disease models, providing insights into immune function and therapeutic potential. However, careful consideration of dosage and potential offtarget effects is necessary for effective use.

Dosing regimens for the antimouse CD4 antibody clone GK1.5 vary significantly across different mouse models and experimental objectives. Here are some key factors that influence dosing regimens:

Dose Range

• General Range: Doses typically range from 50 to 500 μg per injection in in vivo T cell depletion studies using GK1.5.
• Standard Dose: A standard dose range often cited is 200250 μg per mouse, particularly for CD4⁺ T cell depletion studies.

Route of Administration

• Intraperitoneal (IP) Injection: This is a commonly used route for administering GK1.5, particularly for doses like 200250 μg.
• Intravenous (IV) Injection: Some studies may use IV administration, especially for lower doses or specific experimental designs.

Dosing Schedule

• Frequency: Repeated injections are often performed, with a typical schedule of 23 times per week.
• Duration: The duration of treatment can vary based on the specific experimental goals, such as acute or chronic depletion of CD4+ cells.

Experimental Objectives and Conditions

• Animal Strain and Age: The optimal dose can vary depending on the mouse strain and age, as well as their health status.
• Specific Study Goals: Doses may be adjusted according to whether the study focuses on shortterm or longterm effects, or specific immune responses like autoimmune diseases or tumor rejection.

Overall, while there is a general range of dosing for GK1.5, researchers must conduct doseresponse experiments to determine the most effective regimen for their specific mouse model and experimental objectives.