Clone T56/14 is a mouse monoclonal antibody that specifically recognizes human CD71 (transferrin receptor 1), and its most common in vivo applications in mice focus on studies involving human tumor xenografts or humanized models.

Key in vivo applications of T56/14 in mice include:

• Characterizing and analyzing human CD71⁺ cells in tumor xenografts after engraftment into mice, particularly for delineating the presence, distribution, and proliferation status of human tumor cells.
• Flow cytometry and immunoprecipitation assays on tumor samples or tissues collected from treated animals, enabling the identification and quantification of human tumor cells that express CD71 after in vivo experiments.
• Potential use in safety and pharmacokinetic models for humanspecific CART or antibody therapies, assessing both efficacy and potential offtumor toxicity, since T56/14 does not crossreact with the endogenous mouse CD71.

Technical details:

• T56/14 is a mouse IgG1, κ antibody and is considered nonneutralizing for CD71 (i.e., it binds but does not block ligand binding), making it suitable for detection and labeling rather than functional inhibition in vivo.
• It is commonly used in mice with human cells or tissues due to its human specificity; it is not used to target endogenous mouse CD71 (for that, antibodies like OX26 or 8D3 are preferred).

Summary of context:

• In vivo, T56/14 is crucial for detecting and tracking human CD71expressing cells in mouse models, particularly in cancer research and preclinical studies of therapies that target human CD71.
• It is not used as a murine therapy targeting mouse cells, but as a detection or analysis tool in mouse models carrying human cells.

There is no evidence that T56/14 is used to functionally block or deplete CD71⁺ cells in mice, nor that it binds or affects murine transferrin receptor; its use is restricted to detection and analysis in xenograft or humanized mouse studies.

The most commonly used antibodies or proteins assessed alongside T56/14 (antihuman CD71, transferrin receptor) in the literature are those involved in erythroid differentiation and leukocyte phenotype analysis. These include:

• CD235a (Glycophorin A): Frequently costained with CD71 to identify and distinguish erythroid cells and their maturation stages.
• CD36: Used in tandem with CD71 for a more detailed dissection of erythroid differentiation, especially in studies focusing on erythropoiesis.

Other markers and proteins often paired in broader multiparameter flow cytometry panels (depending on application) include:

• CD45: Common leukocyte marker, used to distinguish nonerythroid populations.
• CD34: Used for identifying hematopoietic stem/progenitor cells, especially in the context of hematopoietic differentiation.
• CD38: Sometimes included in panels profiling hematopoietic cells or for cancer characterization.

In studies of activated lymphocytes or in cancer models:

• Activation markers or lineage specific proteins (the specific choice depends on study design) are frequently assessed alongside CD71 due to its upregulation during proliferation or activation.

When the focus is on the erythroid lineage (for example, in studies of anemia, bone marrow evaluation, or stem cell differentiation), the combination of CD71 (T56/14), CD235a, and CD36 is especially common.

Summary Table:
| Comarker/Protein | Main Role in Panel | Typical Use Case |||||| CD235a | Erythroid lineage marker (Glycophorin A) | Erythroid differentiation analysis || CD36 | Erythroid and myeloid marker; lipid uptake | Erythroid maturation assessment || CD45 | Panleukocyte marker | Discriminate leukocytes from others || CD34 | Hematopoietic stem/progenitor marker | Stem/progenitor cell identification || CD38 | Activation/differentiation marker | Immunophenotyping, cancer panels |

Specific combinations in the literature will vary based on whether the context is erythropoiesis, leukemia/lymphoma phenotyping, or cancer xenograft models.

References for couse in literature:

• CD235a and CD36 are most directly cited as commonly paired with T56/14 for erythroid analysis.
• General usage of T56/14 with functional/activation markers and in xenograft models is noted for studies of lymphocyte activation or tumor biology.

The monoclonal antibody clone T56/14 is widely cited in the scientific literature as a reagent targeting human CD71 (the transferrin receptor), primarily for use in flow cytometry and cell phenotyping applications, especially in studies involving erythroid or hematopoietic cells.

Key findings and uses of clone T56/14, as supported by scientific citations, include:

• Specificity: Clone T56/14 is a PEconjugated monoclonal antibody that specifically recognizes human CD71 (transferrin receptor), a cell surface marker commonly used to identify and characterize proliferating cells and immature erythroid cells in flow cytometry assays.
• Application in cell profiling: This antibody is routinely used to distinguish erythroid lineage cells (which have high CD71 expression) from other hematopoietic and blood cells, aiding in research on erythropoiesis, anemia, and various hematologic conditions.
• Role in diagnostic panels: Clone T56/14 is often included in multiparameter flow cytometry panels for immunophenotyping, especially in the analysis of bone marrow or peripheral blood during hematologic disease diagnosis and research.

There are no novel discoveries or unique biological findings directly attributed to clone T56/14 itself—its value is as a recognized tool and standard for CD71 detection in immunological and hematological research. No evidence suggests new functions or characteristics beyond its established role.

Dosing regimens for clone T56/14 (antihuman CD71 monoclonal antibody) are not explicitly detailed, with product literature and public summaries indicating that optimal dosing must be determined by each investigator based on the specific application and mouse model used.

Key context and available details:

• Product guidance for in vivo use: The manufacturer states, "Each investigator should determine their own optimal working dilution for specific applications," suggesting that no universal, modelspecific dosing guidelines exist. Instead, dosing optimization is expected to depend on factors such as:

  • The type of mouse model (e.g., immunocompetent, xenograft, humanized)
  • The experimental objective (prophylactic vs. therapeutic; target tissue)
  • The level of human CD71 expression in the model (since T56/14 is specific for human CD71)
  • Any potential toxicity or efficacy endpoints relevant to the experiment

• General antibody dosing in mice: While clonespecific regimens for T56/14 are not established, general practices for similar mouse monoclonal antibodies (IgG1) in in vivo studies typically use doses ranging from 100–500 µg per mouse, injected intraperitoneally, at intervals determined by the antibody’s halflife and experimental design. However, applying this to T56/14 requires further pilot titration and endpoint monitoring due to its crossreactivity limitations (reacts with human CD71) and possible species differences in target expression.

• Impact of mouse model type:

  • For xenograft models implanted with human tumors, dosing may start at levels similar to other in vivo antibody studies (e.g., 5–10 mg/kg or 100–500 μg/dose), but should be adjusted based on tumor burden, CD71 expression, and observed pharmacodynamics.
  • In nonhumanized or wildtype mice, T56/14 is unlikely to have ontarget effects due to lack of crossreactivity with mouse CD71.

• Lack of published dosing schedules: No published peerreviewed studies or dosing regimens specifically for T56/14 across different mouse models are available in current literature or product summaries.

Recommendations for dosing T56/14 in mouse models:

• Conduct a pilot titration in the chosen mouse model, starting with lower doses (e.g., 5–10 mg/kg, or ≤200 μg per dose).
• Monitor for pharmacodynamic markers (e.g., human CD71 occupancy, tumor inhibition) and toxicity.
• Adjust dosing frequency according to antibody clearance and experimental endpoints, taking cues from dosing schedules for similar IgG1 antibodies (every 3–7 days as a reference), but adapt as needed.

Summary:
There are no standardized or published dosing regimens for clone T56/14 across different mouse models, so dosing should be empirically determined for each model, following general antibody in vivo study guidelines and careful monitoring of response and safety.