Anti-Mouse CD137 (4-1BB) [Clone 3H3] — Purified in vivo PLATINUM™ Functional Grade

Clone 3H3 is a well-characterized agonistic monoclonal antibody targeting mouse CD137 (4-1BB), and it is widely used in in vivo mouse studies to stimulate this co-stimulatory receptor and investigate immune modulation, especially in cancer and infectious disease models.

Key uses and findings in in vivo mouse studies:

• Potent Agonist of CD137: 3H3 is considered a strong agonist of mouse CD137, leading to robust activation of CD8+ T cells and increased production of pro-inflammatory cytokines in treated animals.
• Peripheral Immune Activation: In tumor models, treatment with 3H3 expands liver CD8+ T cells, increases T cell infiltration and activation/exhaustion markers (e.g., PD1, TIGIT) in the spleen and liver, and elevates systemic pro-inflammatory cytokines.
• Antitumor Immunity: 3H3 triggers broad T cell activation which may improve antitumor responses, but also can be associated with T cell exhaustion and limited therapeutic window due to off-target activation.
• Enhancement of B Cell Responses: In malaria infection models, 3H3 augments extrafollicular memory B cell responses, elevates class-switched antibody isotypes (IgG2c), and provides enhanced protection dependent on the IFN? : T-bet axis in B cells.
• Liver Toxicity: Administration of 3H3 can induce significant liver toxicity, characterized by elevated ALT (alanine transaminase) levels. This toxicity depends on the Fc domain isotype and interaction with Fc?Rs, highlighting a risk for immune-related adverse effects.
• Fc and Isotype Considerations: Studies comparing different Fc isotypes (rat IgG2a, mouse IgG1, human IgG4) show that 3H3’s efficacy and toxicity can be modulated by isotype, due to differences in Fc? receptor engagement and immune effector functions.

In summary, clone 3H3 is primarily used in mice to strongly activate CD137 signaling, studying both anticancer immune responses and immunopathology, but its use is limited by the risk of immune-mediated liver damage, which is scrutinized by altering antibody isotypes and Fc domains in comparative experiments.

Recommended Storage Temperature for Clone 3H3 Anti-mouse 4-1BB (CD137)-InVivo

The correct storage temperature for the Anti-mouse 4-1BB (CD137)-InVivo, clone 3H3 (as supplied by Selleck Chemicals), is 4°C in the dark; it is specifically instructed to store the undiluted solution at this temperature and to avoid freeze-thaw cycles. This product should not be frozen.

Other suppliers of the 3H3 antibody may offer different storage options. For example, Syd Labs specifies that their anti-mouse 4-1BB (clone 3H3) is supplied as a 0.2 ?m filtered solution and recommends:

• Long-term storage (up to 12 months from date of receipt): -20°C to -70°C
• Short-term storage (up to 1 month from date of receipt): 2°C to 8°C

They also emphasize avoiding repeated freeze-thaw cycles. However, Selleck Chemicals' datasheet for their version of 3H3 clearly states that the solution should be stored at 4°C, not frozen, and gives no guidance on freezing the product.

Summary Table

Conclusion

For the specific Selleck Chemicals clone 3H3 anti-mouse 4-1BB (CD137)-InVivo antibody, the correct storage is 4°C in the dark, and the product should not be frozen. Always follow the datasheet provided by your supplier, as storage recommendations can vary between manufacturers. If your product comes from a different supplier, consult their specific instructions.

Antibodies and Proteins Commonly Used with 3H3 in the Literature

3H3 is a well-known monoclonal antibody targeting 4-1BB (CD137), a T cell co-stimulatory receptor critical for cancer immunotherapy. In the literature, 3H3 is often studied in combination with other antibodies, immune-checkpoint inhibitors, or engineered protein constructs to enhance anti-tumor immunity or to delineate mechanisms of action. Here’s a summary of the most commonly used agents alongside 3H3, based on recent publications:

Co-stimulatory and Checkpoint Antibodies

• LOB12.3: Often directly compared with 3H3 for their agonistic effects on 4-1BB. While 3H3 exhibits strong intrinsic co-stimulatory activity independent of Fc?R crosslinking, LOB12.3 requires engagement with Fc? receptors (Fc?RIIB or Fc?RIII) on non-T cells for optimal T cell activation. These comparisons help distinguish “strong” vs. “weak” agonistic anti-4-1BB antibodies and their differential requirements for Fc?R-mediated signaling.
• CTX-471-AF: Another anti-4-1BB antibody, used as a comparator to 3H3 in vivo. Studies show 3H3 induces more robust peripheral immune changes, including expansion of liver CD8+ T cells and increased frequencies of exhausted (PD1+TIGIT+) T cells, compared to CTX-471-AF.
• Anti-PD-1/PD-L1 and Anti-CTLA-4: Although not explicitly mentioned in the provided results, 3H3 is frequently used in combination with immune checkpoint inhibitors like anti-PD-1, anti-PD-L1, or anti-CTLA-4 in preclinical and clinical research to test synergistic anti-tumor effects, leveraging the concept that co-stimulation (via 4-1BB) and checkpoint blockade can complement each other for enhanced T cell responses.

Fc? Receptor-Expressing Cells

• Fc?RIIB- and Fc?RIII-Expressing Cell Lines: Used in vitro to study the role of Fc? receptor crosslinking in the activity of anti-4-1BB antibodies. For example, LOB12.3’s activity is restored in co-cultures with these cells, while 3H3’s activity is maintained regardless of their presence. This experimental setup helps dissect the mechanism by which different anti-4-1BB antibodies function.

Engineered Antibody Variants

• Chimeric IgG1/IgG2a Variants: Engineered versions of both 3H3 and LOB12.3 (e.g., LOB12.3-mIgG1, LOB12.3-mIgG2a, 3H3-mIgG1, 3H3-mIgG2a) are used to study the impact of antibody isotype and Fc region on agonistic activity. These constructs reveal that Fc?R engagement can further enhance the activity of certain anti-4-1BB antibodies, though 3H3’s strong agonism is largely independent of this.
• 3H3-mIgG2a-DANA: A modified version designed to test the role of Fc?R binding in antibody activity. This variant is used to confirm that 3H3’s activity is not solely dependent on Fc?R crosslinking.

Summary Table

Additional Context

While the provided results focus primarily on direct comparisons with other anti-4-1BB antibodies and Fc? receptor biology, it is common in the broader literature for 3H3 to be used alongside checkpoint inhibitors (anti-PD-1, anti-PD-L1, anti-CTLA-4), cytokines (e.g., IL-2, IL-15), or other co-stimulatory antibodies (e.g., anti-OX40, anti-GITR) to explore combinatorial immunotherapies. However, these combinations are not detailed in the current search results.

Conclusion

The most commonly used antibodies and proteins with 3H3 in the literature include LOB12.3 (a comparator anti-4-1BB antibody), CTX-471-AF (another anti-4-1BB antibody), and engineered Fc?R-expressing cell lines or chimeric antibody variants to dissect mechanisms of action. These tools help clarify the unique properties of 3H3 as a strong agonistic anti-4-1BB antibody that can activate T cells independently of Fc? receptor crosslinking, unlike some other anti-4-1BB antibodies.

Clone 3H3 has been extensively studied across multiple research contexts, with key findings spanning immunotherapy, biofilm disruption, and replication studies. The scientific literature reveals several important discoveries about this monoclonal antibody clone.

Immunotherapy and Cancer Treatment

Clone 3H3 has demonstrated significant potential in cancer immunotherapy applications. In CD137-targeting studies, clone 3H3 induced a sustained increase in T-cell infiltration and proliferation, showing clear differences compared to other CD137 agonist antibodies. However, its therapeutic efficacy varies depending on the specific context and mouse model used.

In lymphoma treatment studies, clone 3H3 (rat IgG2a) showed preferential activity in prolonging survival of EL4E7 tumor-bearing mice, particularly in Fc?RIII-deficient models. The antibody demonstrated enhanced anti-tumor responses when Fc?RIII was absent, though it did not achieve complete tumor resolution like some other clones. Notably, clone 3H3 exhibits unique binding characteristics - at higher doses, it blocks naturally occurring CD137-CD137L interactions, which distinguishes it from other anti-CD137 antibodies and may explain differences in absolute therapeutic efficacy.

Biofilm Disruption Properties

Clone 3H3 has shown remarkable activity as a pan-amyloid-binding antibody with significant biofilm disruption capabilities. When tested against Salmonella enterica serovar Typhimurium biofilms, clone 3H3 demonstrated the ability to disrupt established biofilm architecture and integrity.

Biofilm Architecture Changes: The presence of clone 3H3 altered biofilm topography, creating a more diffuse staining pattern and reducing the dense packing typically observed in untreated biofilms. Three-dimensional surface analysis revealed that 3H3-treated biofilms showed altered topography with cells appearing outside the main biofilm mass, similar to the effects observed with anti-CsgA serum that completely inhibits biofilm formation.

Bacterial Release: Clone 3H3 treatment increased the release of bacteria from biofilms into supernatants, indicating active disruption of established biofilm structures. This finding has important implications for treating biofilm-associated infections.

Clinical Applications

The biofilm disruption properties of clone 3H3 extend to practical medical applications. Studies have investigated its effects on biofilm growth and architecture on medical devices, particularly intravenous catheters. This research addresses the critical problem of catheter-associated bloodstream infections (CLABSIs), where biofilm formation leads to increased antibiotic resistance and often necessitates catheter removal.

Research Impact and Citations

Interestingly, studies involving clone 3H3 contribute to broader discussions about scientific reproducibility. Research has shown that papers failing to replicate tend to be cited more frequently than those that successfully replicate, with replicable studies receiving approximately 15 fewer citations per year. This citation bias persists even after replication studies are published, highlighting important considerations for evaluating scientific impact based solely on citation metrics.

The diverse applications of clone 3H3 across immunotherapy and infectious disease research demonstrate the versatility of monoclonal antibody technologies and their potential for addressing multiple medical challenges simultaneously.