Anti-Mouse IL-2 [Clone JES6-1A12] – Purified in vivo GOLD™ Functional Grade

Clone JES6-1A12 is most commonly used in vivo in mice for two principal applications: neutralization of endogenous IL-2 activity and formation of IL-2/anti-IL-2 immune complexes to modulate IL-2 signaling.

Key in vivo applications:

• IL-2 Neutralization:
  JES6-1A12 is widely used to block or deplete endogenous interleukin-2 (IL-2) activity. This approach helps to explore the role of IL-2 in immune responses, especially in studies of T-cell biology and cytokine networks. This usage is essential for dissecting the contribution of IL-2 to T-cell proliferation, effector versus regulatory T-cell balance, and immune tolerance.

• IL-2/JES6-1A12 Complex Formation:
  When JES6-1A12 is administered together with recombinant IL-2 to form immune complexes, the resulting conjugate has distinctive biological properties compared to free IL-2. These IL-2/anti-IL-2 complexes selectively stimulate regulatory T cells (Tregs) over effector CD8+ T cells and natural killer (NK) cells, often leading to selective Treg expansion. This technique is utilized to study and promote immunological tolerance, prevent autoimmunity, or protect against transplant rejection in murine models.

Representative disease and model systems:

• Autoimmune disease models:
  The IL-2/JES6-1A12 complex has been shown to be effective for the treatment of autoimmune diseases by expanding regulatory T cell populations and thereby suppressing pathological immune responses.
• Transplantation studies:
  These complexes are also used to enhance graft survival (e.g., in pancreatic islet transplantation) by promoting immune tolerance.
• Immunoregulation research:
  Neutralizing IL-2 with JES6-1A12 in vivo is frequently applied to delineate IL-2’s role in T-cell maintenance, effector function, and immune homeostasis.

Summary Table

Additional notes:

• The antibody’s mechanism—either as a neutralizer or in complex with IL-2—is determined by dosing and the experimental context.
• There is substantial literature precedent and commercial validation for both in vivo uses.

For in vitro detection (ELISA, ELISPOT, IP, WB), JES6-1A12 is also used as a capture or detection antibody but these are not considered in vivo applications.

In the literature, several antibodies and proteins are commonly used alongside JES6-1A12 for various applications:

1. JES6-5H4 Antibody:

   • Applications: This antibody is often used in combination with JES6-1A12 for ELISA capture and detection of mouse IL-2. It is particularly utilized in sandwich ELISA assays where JES6-1A12 serves as the capture antibody, and JES6-5H4 is used for detection.
   • Role: JES6-5H4 recognizes a different epitope on IL-2 compared to JES6-1A12, which allows for efficient detection and quantification of IL-2 in biological samples.

2. PC61 Antibody (anti-mouse IL-2Rα):

   • Applications: This antibody is used to target the alpha chain of the IL-2 receptor. It is often utilized in combination with JES6-1A12 in studies focusing on IL-2 signaling and its regulation.

3. Recombinant Mouse IL-2:

   • Applications: Recombinant mouse IL-2 is used as a standard in ELISA assays when JES6-1A12 is employed for capture. It helps in calibrating the sensitivity and specificity of the assay.

4. Other Immunoenhancing Antibodies (e.g., S4B6):

   • Applications: These antibodies are used in studies to understand the biological effects of IL-2 and its interactions with different antibodies. They share similar biological effects by recognizing overlapping epitopes on IL-2.

These proteins and antibodies are essential tools in research involving IL-2, particularly in studies related to immune response, cell proliferation, and differentiation.

Key Findings from Clone JES6-1A12 Scientific Literature

Molecular and Epitope Characteristics

• JES6-1A12 is a neutralizing monoclonal antibody that specifically recognizes mouse interleukin-2 (mIL-2), not human IL-2, due to a distinct epitope located within the mIL-2 segment E37–P51.
• Epitope Mapping: The critical epitope for JES6-1A12 binding was identified by grafting the mouse IL-2 E37–P51 segment onto human IL-2, which restored binding to the chimeric protein but not to wild-type human IL-2. Alanine scanning and site-directed mutagenesis further delineated the importance of solvent-exposed residues within this region.
• Mechanism of Neutralization: JES6-1A12 binding to mIL-2 blocks interactions with both the α and β/γ chains of the IL-2 receptor, converting complexed IL-2 into a very weak agonist that is effectively neutralized for most effector T cells. However, T regulatory cells (Tregs), which express the high-affinity IL-2 receptor (CD25, or IL-2Rα), can still compete with the antibody and capture IL-2 from these complexes, resulting in selective Treg stimulation.
• Functional Dichotomy: This mechanism leads to a functional dichotomy where JES6-1A12–IL-2 complexes preferentially expand and activate Tregs, while suppressing the activity of effector T cells that express only intermediate-affinity receptors.

Immunological and Therapeutic Effects

• Selective Treg Expansion: JES6-1A12–IL-2 complexes strongly and selectively expand CD25+ regulatory T cells (Tregs), both in vitro and in vivo, which has implications for immunotherapy, autoimmune disease, and transplantation tolerance.
• Graft-versus-Host Disease (GVHD) Prevention: In mouse models, early administration of JES6-1A12 after allogeneic hematopoietic cell transplantation (allo-HCT) markedly attenuates acute GVHD while preserving the graft-versus-leukemia (GVL) effect—a response superior to that achieved with tacrolimus (TAC) treatment.
• Transcriptional Impact: Single-cell RNA-sequencing revealed that JES6-1A12 treatment induces distinct transcriptional signatures in donor T-cell subsets, maintaining a heterogeneous CD8+ T-cell population and supporting GVL activity without exacerbating GVHD.
• Increased LPS Sensitivity: JES6-1A12–IL-2 complexes increase the sensitivity of mice to LPS-induced shock, likely due to potent Treg expansion and altered immune regulation.

Technical and Research Applications

• Neutralization and Assays: JES6-1A12 is widely used for neutralizing IL-2 bioactivity and is suitable for ELISA, ELISPOT, immunoprecipitation, and intracellular staining.
• Purity and Specificity: The antibody is highly pure (>90%), with low aggregation, and specifically recognizes mouse IL-2 without cross-reactivity to human IL-2.

Summary Table

Conclusion

JES6-1A12 is a tool antibody with unique epitope specificity for mIL-2, enabling precise neutralization and selective modulation of IL-2 biology. Its ability to preferentially expand Tregs while suppressing effector T cells has made it a valuable reagent for studying immune regulation, tolerance, and immunotherapy in mouse models. The antibody’s distinctive properties have been leveraged to dissect IL-2 receptor interactions, model immune diseases, and explore novel therapeutic strategies for GVHD and autoimmunity.

Dosing regimens for clone JES6-1A12, an anti-mouse IL-2 monoclonal antibody, vary significantly across different mouse models depending on the experimental context, administration schedule, and whether the antibody is used alone or as part of an IL-2/anti-IL-2 complex. The primary variation stems from the intended application—whether for regulatory T cell (Treg) expansion, IL-2 neutralization, or disease model studies.

IL-2/Anti-IL-2 Complex Dosing for Treg Expansion

When used as an IL-2/anti-IL-2 complex to expand regulatory T cells, the standard preparation involves mixing equal volumes of recombinant mouse IL-2 (30 µg/mL) and anti-mouse IL-2 mAb JES6-1A12 (1 mg/mL) in PBS, with 200 µL injected intraperitoneally per mouse. This results in complexes formed by 1.5 µg of IL-2 with 50 µg of IL-2 mAb per mouse. The injection schedule typically consists of two injections per week, starting either on the day of disease induction (day 0) or at specific time points post-immunization, continuing until the experiment's termination.

For LPS challenge studies examining Treg-mediated effects, mice received three daily doses of IL-2/JES6 (1.5 µg IL-2/dose), with LPS challenge occurring 48 hours after the last dose. This regimen demonstrated that selective Treg expansion could paradoxically increase sensitivity to LPS rather than provide protection.

Neutralization Studies

When JES6-1A12 is used for IL-2 neutralization rather than Treg expansion, the dosing differs substantially. In graft-versus-host disease studies, recipients received a total of 3 intraperitoneal injections of 500 µg per mouse at days 0, 2, and 4 after hematopoietic cell transplantation. This higher dose reflects the antibody's neutralizing activity against IL-2.

Variability Factors

The dosing variations across mouse models depend on several key factors: the experimental objective (Treg expansion versus IL-2 neutralization), the disease model being studied (autoimmune conditions, transplantation, or infection models), and the timing relative to disease induction. The α-IL-2 clone JES6-1A12 binds to a specific site on IL-2 relevant for its interaction with the low-affinity β chain (CD122) of the IL-2 receptor, which influences how the complex modulates immune responses.