Anti-Rat CD28 (Clone JJ319) – Purified in vivo PLATINUM™ Functional Grade

Clone JJ319 is a mouse monoclonal antibody widely used to target rat CD28—a costimulatory receptor on T cells—in a range of in vivo and in vitro studies involving rats. However, its direct use in mice is not standard, as the antibody specifically recognizes rat CD28 and does not cross-react with mouse CD28. Nevertheless, there are a few scenarios where clone JJ319 might appear in in vivo mouse studies:

• Adoptive Transfer Models: Mouse models can be engineered where rat T cells expressing rat CD28 are transferred into mice and then manipulated with JJ319 to study costimulatory pathways or immune modulation.
• Transgenic/Chimeric Models: Mice expressing rat CD28 (either transgenic or as bone marrow chimeras) can be used to allow JJ319 to bind and modulate rat CD28 function within a murine system. These models are used to dissect CD28 function, tolerance, autoimmunity, or costimulation in vivo.
• Xenograft or Humanized Mouse Models: When rat immune cells or tissues are engrafted into mice, JJ319 may be used in vivo to selectively activate or block rat T cell responses within a mouse host.

Typical in vivo applications in these specialized settings include:

• Modulation of T cell activation: JJ319 is frequently used to provide costimulatory signals or to block costimulation by interfering with CD28-CD80/CD86 interactions in adoptively transferred rat T cells.
• Study of immune regulation: It supports research on mechanisms of autoimmunity, transplantation tolerance, or tumor immunity using rat immune cells in mouse models, where precise engagement of CD28 is required.
• Monitoring or depletion: In some chimeric models, JJ319 may be used for in vivo tracking, activation, or ablation of rat T cells.

Key technical limitations:

• JJ319 does not bind murine CD28 and is therefore not useful for direct in vivo targeting of endogenous mouse T cells or immune modulation in standard immunocompetent mouse models.
• The in vivo use of JJ319 in mice requires rat CD28-expressing cells to be present—commonly via adoptive transfer, chimeras, or transgenics.

Summary Table: JJ319 In Vivo Use in Mice

For studies specifically in regular, immunocompetent mice, alternative anti-mouse CD28 clones (such as 37.51 or PV-1) are used.

In summary: JJ319 is typically not used for direct in vivo targeting of mouse CD28; its applications in mice are limited to models where rat CD28 is artificially present. The most common routine use of JJ319 remains in vivo and in vitro modulation of rat, not mouse, T cell responses.

Commonly, the JJ319 antibody against CD28 is used in combination with several other antibodies or proteins for immunological studies in rats. The most frequently co-used antibodies and proteins include:

• Anti-αβ-TCR mAb R73: Used to activate T cells in combination with JJ319 for costimulation studies.
• Hamster anti-mouse CD28 mAb 37.51: Used in comparative binding and signaling studies.
• Mouse anti-human CD3 (clone UCHT1): Used in broader studies involving human antigens for cross-reactivity or mechanistic parallels.
• Mouse anti-human TCRζ (clone 6B10.2): Used when examining TCR signaling pathways alongside CD28 modulation.
• Rabbit polyclonal antibodies to NF-κB p50, c-rel, and USF-2: For downstream signaling analysis after CD28 engagement.
• Mouse anti-human ZAP-70 (clone 3.3.1): For studying TCR/CD28 signal transduction.
• Anti-rat TCR mAb R73: Specifically used for activation of rat T cells in conjunction with JJ319 for functional characterization.

Other related commonly studied antigens/proteins, particularly in the context of T cell activation or immune modulation, include:

• CD3, CD4, CD8: For phenotyping and functional analyses of T cells.
• CD45: As a pan-leukocyte marker.
• CD80/CD86 (B7-1/B7-2): Natural ligands for CD28, often included in costimulatory pathway experiments.
• CTLA-4-Ig fusion protein: Used in comparative studies targeting costimulatory pathways.
• CD11a/LFA-1, CD2: For experiments involving other T cell accessory/costimulatory molecules and their blockade.

In summary, when using JJ319, the literature frequently combines it with antibodies or proteins that:

• Activate T cells (e.g., anti-TCR, anti-CD3).
• Characterize T cell subpopulations or activation state (e.g., anti-CD4, anti-CD8, anti-CD45).
• Analyze costimulatory or inhibitory pathways (e.g., anti-CD80/CD86, CTLA-4-Ig, anti-CD2, anti-LFA-1).
• Examine downstream signaling events (e.g., anti-NF-κB, anti-ZAP-70).

If you need a more specific context or application (e.g., transplantation, autoimmunity, flow cytometry), please clarify for a tailored list.

The key findings from scientific literature regarding clone JJ319 are that it is a conventional monoclonal antibody (mAb) recognizing rat CD28, specifically binding to an epitope near the B7 binding site between amino acid 66 and the transmembrane domain, with a critical residue at position 98 (valine) for binding. JJ319 acts as a functional antagonist in vivo by rapidly inducing internalization of CD28, and has been shown to prolong allograft survival in rat heart transplantation models, though it does not induce tolerance.

Supporting details:

• Epitope Mapping: JJ319 binds downstream of amino acid 66 to the transmembrane region of rat CD28, near the B7 binding site, with valine at position 98 being essential for antibody recognition.
• Functional Properties: JJ319 is described as a conventional anti-CD28 mAb with functional antagonist activity. It causes rapid internalization of the CD28 receptor when administered in vivo.
• Immunological Effects: In rat heart transplantation, modulating with JJ319 extended graft survival but did not result in immune tolerance.
• Cellular Targets: JJ319 binds to rat CD28, which is expressed on thymocytes, mature T cells, and a subset of NK cells.

Additional relevant information:

• The JJ319 clone is distinct from superagonistic mAbs like JJ316, which bind a separate epitope (the C''D loop, aa 37-66).
• JJ319 is widely used to study the topological and functional properties of the CD28 molecule in rats, serving as a basic tool for defining conventional CD28 signaling and costimulation.

Literature consistently identifies JJ319 as a rat-specific, function-blocking anti-CD28 monoclonal antibody with applications in transplantation and immunological research.

Dosing regimens of clone JJ319 (an anti-rat CD28 monoclonal antibody) can vary across mouse models depending on the experimental purpose, mouse strain, and disease context. However, most published dosing practices converge on a few typical regimens, primarily in the context of studies involving graft-versus-host disease (GVHD), immunomodulation, and T cell research.

• Standard Doses Used:

  • 20 μg to 100 μg per mouse per dose is commonly administered, with both single and multiple dosing regimens reported.
  • In GVHD models, dosing at 20 μg every other day for 8 days or a single 100 μg dose are both reported as effective.

• Frequency & Duration:

  • Single-dose and repeated-dose schedules are both used. For example:
    • A single 100 μg intraperitoneal dose.
    • 20 μg administered every other day for 8 days (total of 4 doses), with similar efficacy to the single high dose.
  • The total treatment window typically spans about 1–2 weeks.

• Mouse Model Contexts:

  • Regimens may change slightly depending on the model:
    • In acute GVHD models (such as irradiation followed by allogeneic stem cell transfer), both single high-dose and multiple lower-dose regimens have proven effective.
    • In other T cell modulation studies, some protocols prefer lower, more frequent dosing.

• Route of Administration:

  • Intraperitoneal (IP) injection is the standard route.

• Strain dependence:

  • Most JJ319 studies use BALB/c or C57BL/6 mice (as recipients of rat CD28+ cells) or transgenic models expressing the target antigen. The choice of dose may be influenced by the strain’s body weight and immune responsiveness, but the cited literature does not indicate drastic variations between strains for standard efficacy regimens.

• Other Factors:

  • The choice of dose may be influenced by the specific endpoint (e.g., T cell activation, tolerance induction, graft survival), but for immunosuppression or costimulation blockade, the above ranges are typical.
  • Exact dosages may be further optimized based on experimental pilot studies or prior literature for the mouse model and disease context being used.

Summary Table: JJ319 Dosing Regimens Across Mouse Models

If you have a specific mouse model or disease context in mind (e.g., autoimmune model, tumor immunology), please specify for more targeted information. The regimen may need adjustment based on model characteristics, disease kinetics, and desired effect (agonist vs. antagonist function, immune cell depletion vs. activation).

No evidence from search results suggests highly variable dosing by mouse strain alone, but dose and frequency often align with published effective regimens and pilot study findings for the targeted experimental outcome.