Anti-Mouse CD172a [P84] – Purified in vivo GOLD™ Functional Grade

Clone P84 is most commonly used in vivo in mice to block or neutralize CD172a (SIRPα), a receptor expressed primarily on myeloid cells, in order to modulate immune responses—particularly to study phagocytosis and tumor immunotherapy, as well as to investigate dendritic cell migration and function.

Typical in vivo applications include:

• Blocking SIRPα–CD47 interactions to study phagocytosis of tumor cells, because SIRPα binding to CD47 on target cells inhibits macrophage-mediated phagocytosis ("don’t eat me" signal). Blocking this pathway enhances macrophage-mediated clearance of cancer cells and is a major focus in cancer immunotherapy research.
• In vivo inhibition or modulation of dendritic cell (DC) migration, often to investigate immune cell trafficking and the role of SIRPα+ myeloid cells in inflammation or immune responses.
• Disruption of negative regulatory signals on immune cells (such as macrophages, dendritic cells, and granulocytes) to better understand their biology in both normal physiology and disease models (autoimmunity, infection, cancer).
• Functional depletion or blocking of SIRPα+ cell populations as part of mechanistic studies in immunology and hematology, by directly interfering with the activity or presence of SIRPα+ cells in vivo.

Additional reported experimental uses:

• As an in vivo blocking antibody—P84 is used at low endotoxin levels and is typically functionally validated for animal studies.
• In immunophenotyping and depletion studies of SIRPα-expressing cells measured through flow cytometry, sometimes paired with in vivo manipulation.
• Some formats and protocols specifically use P84 to block dendritic cell migration in inflammatory models.

In summary, clone P84’s most established in vivo use is as a function-blocking antibody for SIRPα, primarily in contexts that investigate innate anti-tumor immunity, phagocytosis, or myeloid cell regulation in mouse models.

Commonly used antibodies or proteins that are used in conjunction with p84 antibodies in the literature include a range of both secondary detection reagents and cell/component specific markers for multiplex or co-localization studies.

The most frequent companions for p84 antibodies are:

• Secondary Antibodies (e.g., Goat anti-Rabbit IgG, Goat anti-Mouse IgG):Used for detection of the primary p84 antibody, typically conjugated to fluorophores or enzymes for visualization.
• Phalloidin:Used as a counterstain for visualizing the cytoskeleton, especially actin filaments. Phalloidin is frequently combined with p84 to contrast nuclear versus cytoplasmic structures in cell imaging.
• DAPI:A nuclear stain used to counterstain DNA, enabling clear localization of nuclear versus non-nuclear staining in immunofluorescence or immunohistochemistry. This is often shown in studies using p84 to localize nuclear matrix proteins.
• Multiplex Biomarkers (Ki-67, p53, ER, PR, HER2):In cancer research, p84 is often combined with proliferation and cancer biomarkers like Ki-67, p53, estrogen receptor (ER), progesterone receptor (PR), and HER2 for extended profiling and differential staining.
• Isotype control antibodies:Used as controls to assess non-specific binding or background staining in experiments involving p84.
• EasyBlot anti-rabbit IgG (HRP):Specifically used in some protocols with p84 for Western blot or immunoprecipitation secondary detection.

Below is a summary table for clarity:

Context and application:
These reagents are used in immunohistochemistry (IHC), immunofluorescence (IF), flow cytometry, Western blot, and immunoprecipitation protocols wherever p84 (nuclear matrix protein) localization, quantification, or multiplex analysis is required. In cancer and cell biology, p84 is a reference or nuclear marker, and its combination with DNA, cytoskeletal, or disease-relevant antibodies allows for sophisticated cellular analyses.

If your question concerns the p84 subunit in the PI3Kγ signaling complex (not the nuclear matrix protein), frequently co-studied proteins are p110γ and p101, and their analysis often includes co-immunoprecipitation, interaction studies, and signaling pathway readouts. If this alternative meaning is relevant, please specify.

Key Scientific Findings from Clone P84 Citations

Molecular Identity and Structure
Clone P84 specifically recognizes mouse CD172a, also known as signal-regulatory protein alpha (SIRPα) or SHPS-1. Early research established that the P84 antigen is identical to SHPS-1, a transmembrane glycoprotein expressed on myeloid cells and involved in cell adhesion and signaling. The molecule exists in two main forms due to alternative splicing: a full-length isoform and a shorter variant lacking an internal exon, which affects the number of extracellular N-glycosylation sites and molecular weight. The discrepancy between the predicted and observed molecular weights is largely due to extensive N-glycosylation.

Functional Mechanisms
SIRPα (recognized by P84) is a receptor-type glycoprotein expressed on myeloid cells such as granulocytes, dendritic cells, macrophages, mast cells, and hematopoietic stem cells. It acts as a substrate for several activated tyrosine kinases and is involved in the negative regulation of receptor tyrosine kinase-coupled signaling pathways. Its most well-characterized interaction is with CD47, an integrin-associated protein expressed on many cell types, notably cancer cells. Binding of CD47 to SIRPα triggers tyrosine phosphorylation of immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in the SIRPα cytoplasmic domain, recruiting and activating the tyrosine phosphatases SHP-1 and SHP-2. This signaling cascade leads to inhibition of macrophage phagocytosis, thereby protecting CD47-expressing cells (including tumor cells) from immune clearance—a mechanism exploited by cancer cells to evade immune destruction.

Applications in Research
The P84 monoclonal antibody is widely used as a tool for identifying and characterizing mouse SIRPα-expressing cells, particularly in flow cytometry and neutralization assays. It has been instrumental in delineating the expression and function of SIRPα in various cell types and experimental contexts.

Comparative Functional Studies with Other Antibodies
Direct comparison of P84 with another anti-SIRPα antibody (MY-1) revealed that while MY-1 can block the CD47-SIRPα interaction and strongly inhibit tumor growth and metastasis, P84 has minimal effect on this interaction and only modestly inhibits tumor growth, with no significant impact on survival in delayed treatment scenarios. This highlights that P84 does not block the key CD47-SIRPα signaling axis, distinguishing its functional profile from other SIRPα-targeting antibodies.

Summary Table

Conclusion

Clone P84 is a foundational reagent for studying SIRPα biology, particularly in mouse models. Its scientific value lies in its specificity for SIRPα, enabling detailed characterization of this immune checkpoint molecule’s expression, structure, and signaling functions, but it does not disrupt the CD47-SIRPα interaction, which is of therapeutic interest in cancer immunology.

Overview of Clone P84 Dosing Regimens

Clone P84 is a monoclonal antibody targeting mouse CD172a (SIRPα), commonly used in preclinical research—especially in immunology and cancer immunotherapy studies. While there is no single standardized dose for all applications, dosing regimens for P84 can vary based on experimental design, route of administration, target cell population, and the specific mouse model being employed.

Dosing for In Vitro and Flow Cytometry Applications

For flow cytometry and in vitro studies, the recommended concentration is typically ≤ 1.0 µg per 10⁶ cells in a volume of 100 µl. Some sources specify even lower amounts for staining, such as ≤ 0.25 µg per test, where a "test" is defined by the manufacturer as the amount of antibody staining a cell sample in a final volume. These guidelines are specific to cell staining and not in vivo administration.

Dosing for In Vivo Mouse Studies

There is limited published data detailing exact in vivo dosing regimens for clone P84 across diverse mouse models. However, some studies and suppliers provide general guidance:

• Functional grade P84 antibodies are available for in vivo use, indicating that they are purified and low in endotoxin for preclinical experimentation.
• In a Salmonella typhimurium infectious mouse model (Nr2f6-deficient mice), a dose of 100 µg was administered. However, the route, frequency, and duration were not specified in the cited source, and this likely represents a single example rather than a standardized regimen.
• No comprehensive, model-specific dosing database is available in the current literature, underscoring the importance of empirical optimization for each study.

Key Considerations and Variability

• Route of Administration: Most in vivo antibody studies in mice use intraperitoneal (i.p.) injection, but the route for P84 specifically is not consistently reported in the available data.
• Frequency and Duration: Published studies using other anti-SIRPα antibodies in mice (e.g., for cancer immunotherapy) sometimes administer antibodies multiple times per week (e.g., three times weekly at 200 µg per dose), but evidence specific to P84 is lacking.
• Dose Optimization: Suppliers and literature consistently recommend that investigators determine the optimal working dilution or dose for their specific application, as performance can vary depending on experimental conditions, mouse strain, and disease model.
• Model Dependency: Dosing may vary with the mouse model (e.g., tumor models, infection models, immune cell depletion studies) and the desired biological effect (blocking, depletion, or staining).

Summary Table: Reported Dosing Examples

Conclusion

There is no universal dosing regimen for clone P84 across all mouse models. For in vitro applications, precise, low-dose guidelines exist (≤1.0 µg/10⁶ cells). For in vivo studies, dosing is less standardized and must be empirically determined by the researcher, with published examples showing variability (e.g., 100 µg in an infection model). Suppliers strongly advise titration and optimization for each experimental setup. Researchers should consult recent literature, antibody datasheets, and pilot experiments to establish the most effective dose, route, and schedule for their specific mouse model and research question.