Anti-Mouse CD45 (Clone I3/2.3) – Purified in vivo GOLD™ Functional Grade

Clone I3/2.3 is a rat monoclonal antibody directed against mouse CD45 that is commonly used in in vivo mouse studies to label, deplete, or track hematopoietic (immune) cells, as CD45 is expressed on all leukocytes except mature red cells.

In vivo applications of clone I3/2.3 include:

• Depletion of hematopoietic cells: By administering the antibody in vivo, researchers can deplete specific populations of CD45? cells, which allows investigation of immune function or cell lineage contributions in murine experimental models.
• In vivo cell labeling: Administering clone I3/2.3 allows for discrimination between cells accessible to the bloodstream and resident cells, particularly in trafficking or tissue localization studies.
• Functional blocking: Antibody binding to CD45 can modulate immune cell function and signaling pathways, affecting T- or B-cell signaling, and cytokine receptor signaling, which is useful in mechanistic immunology research.

Experimental contexts:

• Cell tracking and fate mapping: In vivo labeling allows researchers to distinguish between tissue-resident and circulating immune cells in endpoint analysis (e.g., via flow cytometry using I3/2.3 for in vivo labeling and a non-competing clone for ex vivo staining).
• Immunophenotyping: Because I3/2.3 recognizes all isoforms of CD45, it is used as a pan-leukocyte marker to profile hematopoietic cells in tissues or blood, including in in vivo settings.
• Immunodepletion or modulation: High-purity or low-endotoxin forms of the antibody are used for in vivo depletion or manipulation of immune populations and signaling.

Conjugation and detection formats:

• Clone I3/2.3 is available unconjugated or conjugated (e.g., to PE for flow cytometry), and in low-endotoxin, in vivo-ready formulations.

Summary of use:
In vivo, clone I3/2.3 antibody is injected into mice primarily for immunological studies involving identification, depletion, or tracking of leukocytes based on the expression of CD45—a hallmark of nearly all immune cells—making it a versatile tool in immunology, cell trafficking, and depletion studies in mouse models.

The correct storage temperature for the sterile packaged clone I3/2.3 (anti-mouse CD45 antibody) is 2–8°C, and it should not be frozen.

This is specified by multiple sources describing this antibody clone:

• One supplier notes: "This purified antibody is stable when stored at 2-8°C. Do not freeze".
• Another product specification instructs: "Store undiluted at 4°C and protected from prolonged exposure to light".

Additional details:

• Do not freeze: Freezing may compromise the structural integrity or efficacy of monoclonal antibodies, including clone I3/2.3.
• Light protection: Some conjugated forms (e.g., fluorochrome-labeled) should be protected from light to avoid photobleaching, as specified for some vendors.
• Stability: When maintained at 2–8°C, the antibody remains stable over its recommended shelf-life by the manufacturer.

Always confirm with your product’s accompanying datasheet for any additional storage requirements specific to your formulation.

Commonly used antibodies or proteins paired with I3/2.3 (an anti-mouse CD45 antibody) in the literature are typically those that allow for the identification and characterization of specific immune cell subsets and their states. The following are among the most frequently used:

• CD3 (T cell marker)
• CD19 or B220/CD45R (B cell markers; sometimes specifically mentioned as B220, a CD45 isoform)
• CD11b (myeloid/monocyte marker)
• CD4 and CD8 (T cell subset markers)
• Gr-1 (granulocyte marker)
• Ter119 (erythroid cell marker)
• F4/80 (macrophage marker)

I3/2.3 labels all leukocytes except erythrocytes by targeting a framework epitope on all CD45 isoforms. In practice, it is most commonly used in combination with the markers listed above for multi-parametric flow cytometry or immunohistochemistry, enabling researchers to distinguish and analyze distinct cell populations within mouse hematopoietic tissues.

• When identifying lymphoid populations, anti-CD3 (T cells) and anti-B220/CD19 (B cells) are standard partners.
• For myeloid and granulocyte populations, anti-CD11b and anti-Gr-1 are often used together.
• CD4 and CD8 are always included in panels for distinguishing T cell subsets, frequently in combination with anti-CD3.
• Ter119 is commonly used for gating out erythroid cells, which do not express CD45.

Further, isotype controls matched to rat IgG2b (the isotype of I3/2.3) are often included to assess non-specific binding.

This antibody is utilized in panels to comprehensively characterize the immune landscape in mouse models, allowing exclusion (live/dead, Ter119, non-leukocytes) or inclusion (CD45+, cell type markers) of relevant populations depending on the study focus.

Clone I3/2.3 is a rat monoclonal antibody widely used to identify and study mouse CD45, a key leukocyte common antigen involved in immune cell signaling. The principal findings from scientific literature citing clone I3/2.3 are:

• Recognition of Mouse CD45: Clone I3/2.3 specifically recognizes an epitope on mouse CD45, a family of proteins critical for regulating T- and B-cell activation, growth, and differentiation.

• CD45 Isoforms as Immune Markers: CD45 has multiple isoforms due to alternative splicing, enabling researchers to distinguish between various immune cell types and their differentiation stages using I3/2.3. For example, B220 is a heavily glycosylated isoform found on B cells.

• Widespread Use in Immune Cell Detection: I3/2.3 is the standard antibody for flow cytometry, immunohistochemistry, and functional studies to label and track mouse leukocytes in models of immunity, inflammation, and disease. Studies have applied I3/2.3 to:

  • Discriminate murine dendritic cell subsets and analyze their CD45 isoform expression.
  • Assess immune cell infiltration and function in autoimmune models like EAE and type 1 diabetes.
  • Quantify and sort splenocytes and tumor-infiltrating lymphocytes in oncology and transplantation studies.

• Functional Relevance in Research:

  • In diabetic mouse models, I3/2.3 enabled tracking of immune cell infiltration in pancreatic islets and monitoring the impact of therapeutic interventions on T-cell and macrophage activity.
  • In neuroscience, I3/2.3 staining has been used to study microglia and macrophage function in neuroinflammation and multiple sclerosis models.
  • In basic immunology, foundational work mapped the immunogen for I3/2.3 to T200, later identified as mouse CD45.

• Mechanistic Insights: CD45, as detected by I3/2.3, is central to modulating antigen receptor signaling and, by extension, immune cell responsiveness and autoimmunity susceptibility.

• Technical Citations: Over 10 peer-reviewed publications utilize I3/2.3 for immune phenotyping, often highlighting its reliability and specificity.

In summary, clone I3/2.3 is a cornerstone tool in mouse immunology for identifying and analyzing CD45-expressing leukocytes, enabling advances in both fundamental research and disease modeling.