Anti-Human/Mouse Integrin β7 – Purified in vivo PLATINUM™ Functional Grade

Clone FIB504 is commonly used in vivo in mice for functional blocking studies of integrin β7, particularly to inhibit integrin β7-mediated cell adhesion and immune cell migration. The main in vivo applications include:

• Blocking immune cell migration and adhesion: FIB504 is administered (usually intravenously or intraperitoneally) to living mice to block β7 integrin on circulating immune cells, which disrupts their ability to adhere to and migrate into target tissues.
• Modeling inflammatory diseases: It is frequently used in mouse models of colitis, gut inflammation, and infection to study the roles of β7 integrin in immune cell trafficking to the gut and mucosal tissues.

Additional details:

• The antibody is also sometimes used in in vivo imaging studies to track or modify immune cell localization within tissues, especially in the gastrointestinal tract.
• FIB504 is widely reported in the literature and product datasheets to have in vivo blocking activity, making it a standard tool to interrogate the function of integrin β7 in immune regulation and disease processes.

Summary of main in vivo applications in mice:

• Functional blockade of integrin β7
• Disruption of immune cell migration/homing (especially gut homing)
• Investigating mechanisms in colitis, mucosal immunology, and infection models

Less commonly, FIB504 may also be used in flow cytometry of cells isolated from treated animals to confirm receptor occupancy or modulation in vivo.

Apart from FIB504, which targets integrin β7, several other antibodies and proteins are frequently used together with FIB504 in immunological and virological studies, especially in the context of integrin-mediated cell adhesion and HIV research.

Commonly used antibodies or proteins with FIB504:

• Other monoclonal antibodies against the V2 domain of HIV-1 gp120: These include 1019, 1027, 1017, 1022, 1028, 1029, 1088, 1025, and 6E10. These antibodies are utilized for competitive binding, functional blockade studies, and investigating the interaction between gp120 and integrin α4β7.
• CD3 antibody: Frequently used for T cell identification in multi-color flow cytometry panels alongside FIB504, as FIB504 labels β7, and CD3 marks T cells.
• Isotype controls: Such as Rat IgG2a, are used as controls in flow cytometry when staining with FIB504 to ensure specificity.
• Secondary antibodies: For detection in flow cytometry or immunocytochemistry, such as Goat anti-rat IgG conjugated to Alexa Fluor dyes, often used in combination with primary FIB504 staining.
• Other integrin antibodies: Integrin β7 pairs with integrin α4 (CD49d) to form α4β7, and with αE (CD103) to form αEβ7. Studies may also include antibodies to:
  • α4 (CD49d)
  • αE (CD103)
  • E-cadherin (CD324) (ligand for αEβ7)
  • VCAM-1 (CD106), MAdCAM-1, fibronectin (ligands for α4β7).

Context and Applications:

• HIV research: These combinations are pivotal in studying HIV gp120’s interaction with α4β7-expressing cells, as blocking antibodies (V2 MAbs and FIB504) are used to study inhibition of gp120 binding to integrin α4β7.
• Immune cell phenotyping: Multi-color flow cytometry commonly includes FIB504 with lineage- or activation-marker antibodies (e.g., CD3 for T cells, CD103 for mucosal T cells).
• Functional blockade or competition assays: Panels of V2 domain-specific monoclonal antibodies are used with FIB504 to map critical epitopes, competitive binding sites, and functional effects on integrin-mediated adhesion.

Summary table:

These panels enable comprehensive analysis of immune cell subsets, trafficking, and infection mechanisms where integrin β7 and its partners play essential roles.

Clone FIB504, an antibody targeting integrin β7, has yielded several significant findings across multiple research areas, demonstrating its versatility as both a research tool and potential therapeutic target.

Role in Multiple Myeloma Cell Adhesion and Migration

Research has demonstrated that blocking integrin β7 with FIB504 significantly reduces multiple myeloma (MM) cell adhesion to stromal elements including bone marrow stromal cells (BMSCs), fibronectin (FN), and E-cadherin (E-CDH). The antibody also impaired MM cell migration, with these effects being validated through complementary shRNA silencing studies. Rescue experiments using a silent mutant ITGB7 that resisted shRNA knockdown successfully restored both adhesive and migratory functions, confirming the specificity of integrin β7's role in these cellular processes.

Development as a Humanized Therapeutic Antibody

FIB504 served as the parent antibody for developing rhuMAb Beta7, a humanized monoclonal IgG1κ antibody targeting integrin β7. The humanization process involved CDR grafting into a consensus framework, which initially resulted in complete loss of antigen binding. Researchers restored binding through framework optimization, identifying a critical L78F substitution in VH, followed by CDR repair mutations (T31D and Y32L in CDR-L1) that fully restored β7 binding affinity comparable to the parent antibody. This demonstrates the technical challenges and solutions in translating research antibodies into potential therapeutics.

Differential Effects in Experimental Autoimmune Encephalomyelitis

Comparative studies in mouse models of experimental autoimmune encephalomyelitis (EAE) revealed important mechanistic distinctions between integrin-targeting strategies. While anti-α4 antibodies (mPS/2) significantly ameliorated disease severity with statistical improvements in both disease scores (P = 0.003) and histological inflammation scores (P = 0.009), the anti-β7 antibody (muFIB504) showed no effect on disease severity or CNS inflammatory cellular infiltration. Strikingly, survival rates differed dramatically: 90% of animals receiving anti-α4 treatment survived to day 21, compared to only 30% with anti-β7 (muFIB504) treatment and 36% in controls (P = 0.0005). These findings suggest that while α4β7 integrin plays a role in mucosal immunity, the α4β1 integrin pathway may be more critical for CNS inflammation in EAE.

Functional Characteristics and Applications

FIB504 recognizes a 130 kDa glycoprotein epitope on both human and mouse integrin β7, demonstrating cross-species reactivity that enhances its utility in translational research. The antibody effectively blocks β7 integrin-mediated cell adhesion in both in vitro and in vivo studies. Integrin β7 functions by forming heterodimers with α4 (CD49d) to create the α4β7 integrin complex or with αE (CD103) to form αEβ7 integrin. The α4β7 complex mediates adhesion to mucosal endothelial cells through interactions with mucosal addressin cell adhesion molecule-1 (MAdCAM-1), promoting leukocyte transendothelial migration—a critical process in inflammatory responses.

These collective findings establish FIB504 as a valuable tool for investigating integrin β7 biology across diverse disease contexts, from cancer cell behavior to autoimmune inflammation, while highlighting the context-dependent nature of integrin-targeted interventions.

Dosing regimens of clone FIB504 (anti-integrin β7 antibody) in mouse models vary by disease model, experimental aim, and administration schedule. In published studies, the most detailed and consistent dosing regimens are reported in models of autoimmunity, such as lupus or colitis, but less frequently in other indications.

Key Dosing Regimens Across Models:

• MRL-lpr Mouse Model (Systemic Autoimmunity):

  • Typically 500 µg per dose, administered intraperitoneally (i.p.) on days 7, 9, and 11.
  • This regimen is used to reduce type 2 innate lymphoid cells (ILC2s) and assess immunomodulatory effects.

• General Antibody Dosing Guidance:

  • Frequency often ranges from every 3 to 4 days for functional studies, though exact FIB504 protocols can differ.
  • Amount may require titration for optimal effect, but the above 500 µg/dose in the MRL-lpr model is a common reference.

• Other Mouse Models:

  • Some protocols describe dosing based on µg per number of cells (for in vitro or adoptive transfer experiments), such as 5 µg per million cells in a 100 µl volume for certain applications.
  • For flow cytometry or cell depletion, doses as low as ≤0.5 µg per million cells are used, but these are not relevant for in vivo functional blocking.

Summary Table: FIB504 Dosing by Mouse Model

Essential Context and Supporting Details:

• Route of administration is typically intraperitoneal (i.p.) for in vivo studies, though intravenous (i.v.) or subcutaneous (s.c.) routes are possible depending on the experimental setup, but not commonly reported with FIB504 in mice.
• Dosing schedules (days post-immunization or post-disease induction) are usually tailored to the disease model and are critical for achieving optimal blockade of the β7 integrin.

Additional Relevant Information:

• The FIB504 antibody is effective in blocking both mouse and human β7 integrin in cell adhesion assays and in vivo models.
• For optimal experimental results, preliminary dose titration is often recommended, as disease severity, mouse strain, and experimental design can all influence optimal dosing.
• Commercial suppliers and protocols provide general guidance, but peer-reviewed primary literature remains the best source for precise regimens in a given disease model.

No example was found of alternate regimens for non-systemic autoimmune models or tumor models using FIB504; where precision is necessary, consult the methods section of relevant studies or directly titrate in pilot experiments.

In summary: The most common FIB504 in vivo regimen is 500 µg i.p. every 2 days (e.g., days 7, 9, and 11) in models like MRL-lpr, but regimens can be adjusted depending on model requirements and experimental goals.