Anti-Human CD19 [Clone 4G7] – Purified in vivo PLATINUM^TM Functional Grade

Clone 4G7, an anti-human CD19 monoclonal antibody, is commonly used in vivo in mice for targeting and manipulating B cells, as well as in the development and monitoring of CAR-T cell therapies.

Key in vivo applications in murine models include:

• Functional B Cell Depletion and Targeting: Clone 4G7 is used to selectively deplete or target human CD19+ B cells in humanized mouse models. This supports mechanistic studies of B cell biology and immunotherapy efficacy.
• Development and Testing of CAR-T Therapies: The scFv portion of multiple clinical-stage anti-CD19 CARs (e.g., UCART19, ALLO-501) is derived from clone 4G7, and mouse models are utilized to assess CAR-T cell function, persistence, and off-target effects.
• Detection and Characterization: Clone 4G7 and related anti-idiotype antibodies are used for flow cytometric and immunohistochemical detection of human CD19 or CAR-T cells carrying 4G7-derived components within mouse tissues and blood.
• Epitope Mapping and B Cell Biology: Studies leveraging clone 4G7 support deeper characterization of CD19’s role and distribution on B cells, including in context of lymphoid malignancy xenografts in mice.
• DNA-Encoded Monoclonal Antibody Expression: The 4G7 genetic sequence has been delivered to mice via DNA-based platforms to enable in vivo expression of anti-CD19 antibody, facilitating pharmacokinetic assessments and rapid screening before advancing to clinical studies.

In summary, clone 4G7 is widely used in vivo in mice for research into B cell biology, preclinical immunotherapy development (notably CD19-targeted CAR-T and antibody therapies), and for the detection and monitoring of human CD19 activity via immunophenotyping and bioanalytical assays.

In the literature, the 4G7 antibody, which targets CD19, is often used in conjunction with other antibodies or proteins in various research and therapeutic applications. Here are some examples of commonly used antibodies or proteins that are often combined with 4G7:

1. Anti-Idiotypic Antibodies (A8 and E1): These antibodies are specifically raised against the 4G7-derived CAR single-chain variable fragment (scFv). They are used in blocking experiments or flow cytometry analyses to detect CAR T cells.

2. CAR T Cells: The 4G7 antibody is frequently engineered into CAR T cells, which are used to target and eliminate CD19-positive B cells. This application is primarily in the context of B-cell malignancies such as leukemia and lymphoma.

3. Other CD Markers: In flow cytometry, 4G7 is often combined with antibodies targeting other CD markers to identify and analyze specific cell populations. For example, CD3, CD4, and CD8 antibodies are commonly used to study T-cell subsets.

4. Bispecific Antibodies and Immune Checkpoint Inhibitors: While not directly paired in the same application, the broader therapeutic landscape includes the use of bispecific antibodies and immune checkpoint inhibitors like PD-1/PD-L1 inhibitors, which are evaluated separately or in combination with other targeted therapies.

5. B7-H4-Directed Agents: Though not directly combined with 4G7, B7-H4–directed agents represent another area of research in cancer therapy, targeting different aspects of the immune response.

These combinations are crucial for expanding the therapeutic and diagnostic capabilities in cancer research and treatment.

Clone 4G7 is a monoclonal antibody developed against human CD19, primarily used for immunophenotyping B lymphocytes, including both normal and malignant cells such as those in chronic lymphocytic leukemia (CLL). Key findings from scientific literature and cited sources regarding clone 4G7 include:

• Origin & Specificity: Clone 4G7 was generated by immunizing mice with CLL cells and is specific for human CD19, a surface marker expressed broadly on B cells. This specificity makes it particularly valuable for identifying B-cell populations in research and diagnostic contexts.

• Applications in Diagnostics & Flow Cytometry:

  • Widely used in flow cytometry panels to quantify normal and malignant B cells in human blood and tissue samples.
  • Considered a standard tool for immunophenotyping in hematological malignancies due to its reliability and consistency.
  • It is also referenced in epitope mapping studies, highlighting differences in recognition compared with other anti-CD19 clones (such as FMC63 and 4G7-2E3). These mapping studies are important for understanding cross-reactivity and compatibility with CD19-targeting therapeutics.

• Role in CAR-T and CD19-based Therapies:

  • The single-chain variable fragment (scFv) derived from 4G7 is incorporated in some chimeric antigen receptor (CAR) designs, such as those for UCART19, ALLO-501, and ALLO-501A allogeneic CAR-T cell products. This underpins its translational impact in immunotherapy.
  • Anti-idiotype (anti-id) antibodies specific for 4G7-derived CARs are utilized to detect expression levels, pharmacokinetics, and potential immunogenicity of therapeutic CAR T cells.
  • These reagents can discriminate between endogenous CD19 and exogenous anti-CD19 CARs in cell manufacturing and patient monitoring contexts.

• Epitope Competition & Blocking:

  • Some anti-CD19 clones, such as clone HIB19, can partially block staining by 4G7, indicating that they bind to overlapping or sterically proximate epitopes on the CD19 molecule. This has implications for multicolor flow cytometry panel design and for interpreting competitive binding assays.

• Affinity Characteristics:

  • The affinity of antigen-binding domains derived from 4G7 falls within the nanomolar range (Kd ∼1 nM), consistent with high-affinity antibody binding appropriate for both diagnostic and therapeutic purposes.

• Clinical and Preclinical Utility:

  • 4G7's recognition of both normal and malignant B cells supports its use in a variety of research protocols and clinical studies, especially for diseases where B-cell enumeration is essential.
  • Studies have also used clone 4G7 as a reference to evaluate the effects of CD19-directed therapies, including CAR T cells and monoclonal antibody treatments, on B-cell populations and CD19 expression.

Summary Table: Key Findings for Clone 4G7

These findings underscore 4G7's continuing importance in B-cell biology research, clinical diagnostics, and as a foundational component of some CD19-targeted immunotherapies.

Dosing regimens of clone 4G7, an anti-human CD19 monoclonal antibody, are not standardized across mouse models, and there is limited published guidance regarding its precise dosing protocols in vivo.

Essential context:

• Clone 4G7 targets the human CD19 antigen, common in B cell studies and therapies.
• Most available data indicate that dosing schedules for 4G7 in mice must be tailored based on the research context, such as tumor xenograft models, depletion experiments, or preclinical CAR-T studies.
• By contrast, commonly used antibodies for mouse targets (e.g., anti-mouse CD19 [clone 1D3], anti-mouse CD8, or anti-mouse CTLA-4) have more established dosing protocols, typically ranging from 100–250 μg per mouse, given intraperitoneally every 2–3 days.

Supporting details:

• Applications: 4G7 is often used in humanized mouse models or in studies aiming to mimic the clinical setting for CD19-directed therapies, such as tafasitamab or CART19 cell therapy.
• Regimen variability: Regimens may depend on factors like mouse strain, level of humanization, and specific experimental endpoints (e.g., B cell depletion, tumor burden reduction).
• Comparative note: Preclinical dosing regimens for antibodies in mice are frequently more intensive (higher frequency/lower interval) than human dosing schedules.

Additional relevant information:

• Toxicity and efficacy: Dosing needs to be empirically determined for each model, balancing efficacy (e.g., degree of CD19 occupancy/depletion) with tolerability and avoiding excessive immunogenicity or off-target effects.
• Humanized models: Clone 4G7 should only be used in models expressing human CD19 (not wild-type mice), such as transgenic or engrafted models.
• Reporting gaps: Few studies publish comprehensive optimization of 4G7 dosing across different mouse backgrounds, so researchers must adjust regimens iteratively using pilot studies.

In summary, dosing of clone 4G7 in mouse models is individualized and lacks the standardized protocols found for widely used mouse-targeted antibodies; researchers must empirically optimize dosing depending on the mouse model and study goals.