Anti-Mouse CD31 (PECAM-1) [Clone 390] — Purified in vivo PLATINUM™ Functional Grade

In Vivo Applications of Clone 390 in Mice

Clone 390 is a widely used rat monoclonal antibody against mouse CD31 (also known as PECAM-1), a marker predominantly expressed on endothelial cells and weakly on certain leukocytes and platelets. Its in vivo applications leverage both its targeting specificity and functional blocking capabilities.

Key In Vivo Applications

• Intravital Imaging: Clone 390 has been utilized for fluorescence-guided intravital microscopy, enabling real-time visualization of endothelial cells in living mice. For example, conjugated forms (e.g., RPE- or AF488-labeled) are injected into tumor-bearing mice, allowing microscopic navigation and imaging of vascular structures in situ. The minimal effective dose for detectable fluorescence signal in perfused tissue segments was found to be at least 1200 ng, with higher doses resulting in better imaging but also highlighting dose-dependent capture efficacy.
• Blocking CD31-Mediated Functions: Clone 390 is employed to inhibit CD31/PECAM-1-mediated cell-cell adhesion in vivo. This has been used to study processes such as leukocyte transendothelial migration, angiogenesis, and endothelial cell interactions. The antibody’s blocking activity makes it a valuable tool for investigating the role of CD31 in inflammation, immune cell trafficking, and vasculature remodeling.
• Immunofluorescence and Flow Cytometry: Although primarily in vitro applications, validated protocols for flow cytometry using clone 390 on mouse tissues (e.g., thymocytes, splenocytes) are also referenced, supporting its utility in ex vivo analysis of endothelial and hematopoietic cell populations.
• Combination Studies: In some studies, clone 390 is used in combination with other antibodies (e.g., anti-CD54) to enhance fluorescent signal intensity and improve the quality of intravital imaging, suggesting synergistic utility in complex experimental designs.

Technical Considerations

• Formulation: Clone 390 is available in various formats suitable for in vivo use, including purified, low-endotoxin, and sterile-filtered preparations.
• Dosage: Effective dosing for imaging applications starts at 1200 ng, with tissue concentrations and capture efficacy dependent on the specific experimental setup.
• Specificity: Clone 390 targets a unique epitope within the IgD2 domain of CD31, allowing for selective detection and blockade of CD31 functions in vivo.

Summary Table: Common In Vivo Uses of Clone 390

Conclusion

Clone 390 is a versatile tool for studying vascular biology and inflammation in mice, with principal in vivo applications in intravital imaging of endothelial cells and functional blockade of CD31-mediated processes. Its use is supported by robust validation for specificity, efficacy, and compatibility with advanced imaging techniques.

Commonly Used Antibodies and Proteins Paired with 390 in the Literature

390 refers to a monoclonal antibody (clone 390) specific for mouse CD31, also known as platelet-endothelial cell adhesion molecule-1 (PECAM-1), and is widely used in immunology research. In the scientific literature, 390 is frequently employed in combination with other antibodies or protein therapeutics to enhance binding, delivery, or therapeutic effects.

Notable Pairings with Clone 390

• MEC13.3: A rat anti-mouse IgG monoclonal antibody targeting a different epitope on PECAM-1, MEC13.3 is often co-administered with 390 to achieve "collaborative enhancement" of binding. This combination has been shown to increase the apparent binding affinity of therapeutic fusion proteins (such as 390 scFv-TM) to the endothelial cell surface, as well as enhance downstream biological effects such as activated protein C (APC) generation. Specifically, pairing 390 with MEC13.3 increased binding affinity by ~4-fold and boosted APC generation by up to 6-fold compared to 390 alone. Co-immunoprecipitation experiments confirmed that MEC13.3, 390, and PECAM-1 form a complex on the cell surface.
• 390 scFv-TM: This is a recombinant protein consisting of the extracellular domain of mouse thrombomodulin (TM) fused to a single-chain variable fragment (scFv) derived from clone 390. When used alone or in combination with MEC13.3, this fusion protein targets PECAM-1 to modulate coagulation and inflammation at the endothelial surface, particularly in models of acute lung injury and ischemia/reperfusion. The therapeutic effect (APC generation) is significantly enhanced when 390 scFv-TM is paired with MEC13.3.
• Self-paired 390: In some experiments, the parental 390 antibody is used to "self-pair" with the 390 scFv-TM, but this typically inhibits rather than enhances binding, suggesting that the epitope specificity is crucial for collaborative effects.

Additional Proteins and Antibodies in Broader Context

While clone 390 itself is not typically used in the context of engineered antibody fragments or multispecific formats like those described for IgG Fc regions (e.g., HexaBody, DLE, DE, or YWA mutants), it is sometimes referenced alongside other PECAM-1-targeting reagents in endothelial biology studies. However, the most consistent and well-documented pairing in the literature is with MEC13.3 when the goal is to enhance PECAM-1 targeting and therapeutic protein delivery.

Summary Table: Common Pairings with Clone 390

Conclusion

The most commonly documented pairing with clone 390 in the literature is the rat anti-mouse PECAM-1 antibody MEC13.3, used to enhance the binding and therapeutic efficacy of PECAM-1-targeted fusion proteins such as 390 scFv-TM. These combinations are primarily leveraged to increase endothelial targeting and amplify downstream biological effects in preclinical models. Other pairings (e.g., self-paired 390) are mainly used as controls to confirm epitope specificity. There is no strong evidence in the current literature for the routine pairing of clone 390 with other engineered antibody fragments or Fc mutants.

The term “clone 390” in scientific literature most often refers to the monoclonal antibody clone 390, which targets the CD31 (PECAM-1) antigen, commonly used in flow cytometry and related immunological applications. The key scientific findings associated with citations of clone 390 can be summarized as follows:

• Clone 390 is widely used as an antibody to detect mouse CD31 (PECAM-1):

  • CD31 is an important marker for endothelial cells and is involved in studies of angiogenesis (blood vessel formation), inflammation, and immune cell migration.
  • Clone 390’s specificity for mouse CD31 makes it a standard reagent in both basic research and preclinical models of cardiovascular and immunological diseases.

• Applications of clone 390 include:

  • Identification and quantification of endothelial cells in tissue samples.
  • Study of vascular biology, including neovascularization and vascular remodeling.
  • Analysis of inflammatory responses, since CD31 plays a role in leukocyte transmigration.
  • Utility in flow cytometry, immunohistochemistry, and immunofluorescence, facilitating the characterization of cellular populations and tissue structures.

• Citations of clone 390 often contribute to research elucidating:

  • The mechanisms of angiogenesis in cancer, development, and tissue repair.
  • The role of PECAM-1/CD31 in immune system function and vascular integrity.
  • Experimental models assessing the effects of drugs or genetic modifications on endothelial cells.

• Antibody specifications:

  • Clone 390 is manufactured by numerous vendors and is conjugated with various fluorophores (e.g., AF647) for compatibility with multiparameter cytometry and microscopy.

In summary, clone 390 is a cornerstone tool in immunological and vascular research, cited in a wide range of studies focusing on endothelial cell biology, vascular disease, and immune responses. There is strong consensus regarding its specificity and utility for detection of mouse CD31, underpinning its frequent citation in relevant scientific literature.

Dosing regimens of clone 390 (an anti-mouse CD31/PECAM-1 antibody) vary by application, tissue, and experimental aim, but there is limited standardized dosing information across different mouse models in the current literature.

• Identification and Application: Clone 390 is used primarily for labeling or blocking CD31 in mice, including applications such as immune cell tracking, vascular biology, and flow cytometry.
• Co-Administration with Other Clones: In in vivo labeling protocols, combination regimens—for example, 1200 ng per mouse of clone 390 administered intravenously, often with another clone at the same dose—have been reported to improve vascular labeling efficiency. Lower doses (e.g., <800 ng) were insufficient for reliable detection in these settings.
• Functional Dose Variation: The specific dose can depend on:
  • Objective: Whether the goal is blocking, depletion, or detection.
  • Route: Intravenous injection for vascular labeling is common.
  • Mouse strain and experimental design: Some protocols adjust for body weight, immune status, or strain sensitivity.

The published dosing information for clone 390 is sparse compared to more commonly used functional antibodies (like anti-CD4 or anti-PD-1), for which standardized doses and schedules are widely reported. Most protocols with clone 390 emphasize careful titration and, where necessary, co-injection with other antibodies to optimize marker detection or vascular labeling rather than systemic immunomodulation.

• No substantial evidence was found of regimen differences across disease models (e.g., cancer vs. inflammation) specifically for clone 390—protocols are typically specialized for the technical requirements of vascular or endothelial cell detection.

In summary, most published in vivo protocols use intravenous doses of 1200 ng per mouse of clone 390 (sometimes in combination with other clones), with little evidence for major regimen variation by mouse model or disease context. For specific blocking or depletion studies, researchers are advised to titrate doses empirically for their mouse model and endpoint.