Anti-Mouse/Human CD45R (Clone RA3-6B2) – Purified in vivo PLATINUM™ Functional Grade

Clone RA3-6B2 is commonly used in vivo in mice for B cell depletion and immunomodulation, making it a critical tool in experimental studies of B cell function and immune regulation.

Key in vivo applications include:

• Depletion of B cells: RA3-6B2 binds to the CD45R/B220 antigen, a marker expressed on most B cells in mice, and is widely used to selectively eliminate B cells via antibody-mediated depletion. This allows researchers to create B cell-deficient models to study the role of B cells in immunity or disease.
• Modulation of B cell responses: Administration of RA3-6B2 has been shown to modify immune responses by inhibiting B cell function in vivo, useful for exploring how B cells influence both normal and pathological processes.
• Immunomodulation in disease models: RA3-6B2 is used to study the impact of B cells in various murine disease models, such as autoimmunity, infection, or cancer, often by either depleting or functionally altering the B cell compartment.
• Functional studies of immune regulation: The antibody provides a means to dissect immune regulation, such as studying the interplay between B and T lymphocytes or the effects of B cell absence on other immune cells and responses.

In summary, RA3-6B2’s principal in vivo uses are B cell depletion, immunomodulation, and elucidation of B cell function in experimental mouse models. These applications are critical for understanding the roles of B cells in health and disease, and for preclinical testing of immune interventions.

In the literature, the RA3-6B2 antibody, which targets CD45R/B220, is commonly used in combination with other antibodies to profile immune cell populations comprehensively. Some of the other commonly used antibodies or proteins used with RA3-6B2 include:

• CD19: Often used as a more specific B cell marker compared to CD45R/B220, as CD19 is more restricted to B cells.
• CD3: A T cell marker used to identify T lymphocytes.
• CD4 and CD8: Used to differentiate between T helper and cytotoxic T cells, respectively.
• NK1.1: For identifying natural killer (NK) cells.
• CD11b: Used to identify myeloid cells such as macrophages and granulocytes.
• IgM and IgD: These can help in identifying different stages of B cell maturation.
• CD21 and CD23: These are also markers for B cells at different stages of development.

These antibodies are typically used in flow cytometric analysis, immunohistochemistry, and other immunological techniques to study immune cell subsets and their functions.

The RA3-6B2 clone is a monoclonal antibody that specifically targets the CD45R/B220 isoform of the CD45 glycoprotein. It is widely used in scientific research as a marker for B cells and certain subsets of T cells and NK cells. Here are some key findings from citations involving the RA3-6B2 clone in scientific literature:

Key Findings

1. CD45R/B220 Expression:

   • The RA3-6B2 antibody binds to the extracellular domain of CD45R/B220, an isoform of CD45 dependent on the expression of exon A and specific carbohydrate residues.
   • It is expressed on B lymphocytes at all stages from pro-B to mature and activated B cells but is decreased on plasma cells and a subset of memory B cells.

2. Cellular Specificity:

   • The RA3-6B2 clone is commonly used as a B cell marker, although it can also bind to abnormal T cells, NK cells, and certain lymphocyte progenitors.
   • It is noted for its expression on B cells, T cell subsets, and NK cell subsets, making it valuable for distinguishing these cell types.

3. Effects on B Cell Responses:

   • The RA3-6B2 antibody has been reported to enhance isotype switching during in vitro B-cell responses but inhibit in vivo B-cell responses.
   • This suggests that while it can modulate B cell function, its effects depend on the context of the assay.

4. Cross-Reactivity:

   • The RA3-6B2 clone has been reported to cross-react with activated human T lymphocytes, although its primary use is for mouse cells.

5. Developmental Regulation:

   • The expression of CD45R on the B cell lineage is developmentally regulated, with varying levels across different stages of B cell maturation.

These findings highlight the RA3-6B2 clone's utility in immunological research, particularly for studying B cell development and function.

Dosing regimens for clone RA3-6B2 (anti-mouse CD45R/B220 monoclonal antibody) vary primarily by application (e.g., flow cytometry, immunohistochemistry, in vivo depletion), tissue target, and mouse model, rather than by a standardized dose per strain or disease model.

Key details for common applications:

• Flow Cytometry: The recommended dose is typically ≤0.5 µg per test (using ~10⁵–10⁸ cells/sample in 100 µL volume). Laboratories are strongly advised to titrate the antibody to optimize staining for specific cell types and tissue contexts.
• Immunohistochemistry: Application in paraffin-embedded or frozen sections is possible, with working dilutions recommended by supplier datasheets. Mouse strain differences in tissue autofluorescence or epitope accessibility may justify additional titration.
• In Vivo Functional Studies/Cell Depletion: Administration regimens can vary widely. Published reports suggest qualitative effects on B and T cell differentiation and antibody levels in normal mice. Dosing should reflect experimental goals—such as modulation versus depletion—with dose ranges and schedules determined empirically for each mouse model based on expected cell frequency, tissue accessibility, and antibody pharmacokinetics.

Mouse Model-Specific Considerations:

• Genetic Background: The expression level of CD45R/B220 and antibody accessibility may differ in mutant or disease models (e.g., lpr/lpr mice, myeloproliferative/malignancy models), affecting optimal antibody dose and labeling efficacy.
• Disease Context: Some mouse models with altered immune states (e.g., autoimmunity, cancer) may require higher doses for in vivo depletion or modulation due to increased B cell numbers or altered tissue distribution.

General Guidance:

• Always titrate RA3-6B2 for each application and mouse model, as factors like cell count, target antigen density, and tissue characteristics influence dosing requirements.
• For flow cytometry, start at 0.5 µg/test and decrease with strong signals or increase where signal is weak, always checking background staining. For functional studies (depletion/modulation), follow published protocols for similar models, adjusting as necessary for cell population and experimental outcome.
• Manufacturers and published protocols consistently recommend empirical optimization and caution against assuming a universally applicable dose.

In summary, dosing regimens of clone RA3-6B2 depend on the mouse model’s biology and experimental application, requiring empirical titration and adjustment in every context.