Anti-Mouse CD11b – Purified in vivo GOLD™ Functional Grade

Clone M1/70 is commonly used in in vivo mouse studies to target CD11b-expressing cells, which include macrophages, monocytes, neutrophils, and some dendritic cells and NK cells. This antibody has several well-established functional applications in live animal research.

Depletion Studies

One of the primary in vivo applications is cell depletion, where M1/70 is used to selectively remove CD11b-expressing myeloid cells from the system. This approach allows researchers to study the functional role of these immune cell populations by observing the effects of their absence.

Blocking and Neutralization

M1/70 serves as a blocking antibody to inhibit CD11b function in vivo. The antibody can block iC3b binding to its receptor, thereby interfering with complement-mediated interactions and other CD11b-dependent cellular functions. This neutralization capacity makes it valuable for understanding the role of CD11b in various immune responses and inflammatory processes.

Imaging Applications

Recent applications include using radiolabeled M1/70 for PET-CT imaging to visualize bone marrow cell density changes in response to therapy. Specifically, 64Cu-labeled M1/70 has been employed to noninvasively assess functional bone marrow and monitor CD11b+ cell populations following chemotherapy treatments like Abraxane.

Detection and Phenotyping

Beyond functional manipulation, M1/70 is widely used as a marker antibody to detect and quantify CD11b expression on various myeloid cell populations in vivo, helping researchers track macrophages, granulocytes, neutrophils, and NK cells during experimental treatments.

For in vivo studies requiring high purity and low endotoxin levels, Ultra-LEAF™ purified formulations (with endotoxin < 0.01 EU/µg, azide-free, and 0.2 µm filtered) are specifically recommended to minimize unwanted immune activation.

Commonly used antibodies or proteins that are cited alongside M1/70 (anti-CD11b) in the literature for immunophenotyping or functional studies of myeloid and immune cell populations include:

• F4/80 (BM8): Widely used as a murine macrophage marker, often in conjunction with CD11b to distinguish macrophage subsets.
• CD68 (FA-11): Another marker for murine macrophages; used together with CD11b and F4/80 in multiparametric flow cytometry or immunohistochemistry.
• CD18: Forms a heterodimer with CD11b (together called Mac-1 or CR3). Some studies use anti-CD18 antibodies to further resolve integrin subunits or defined functional receptor roles.
• Ly6C, Ly6G: Common in myeloid panel combinations to distinguish between monocytes, neutrophils, and other granulocytes when co-stained with CD11b.
• CD11c: Used to delineate dendritic cells (DCs), which can also express CD11b at varying levels.
• CD45: A pan-leukocyte marker, typically included as part of lineage identification in immune cell profiling.
• MHC class II (I-A/I-E, anti-MHC II): To define antigen-presenting cells, often paired with myeloid markers including CD11b.
• CD14, CD16/32, CD115: For functional and subset identification of monocytes/macrophages.
• PD-1, CTLA-4, and other checkpoint antibodies: Used in experimental contexts involving immunotherapy combinations, immune cell infiltration studies, or functional blockade studies, as seen in tumor microenvironment research.

These markers are frequently combined with M1/70 in multicolor flow cytometry panels, immunohistochemistry, and cell depletion or enrichment protocols to define, characterize, and manipulate mouse myeloid and related immune cell subsets.

These combinations allow researchers to resolve macrophage, monocyte, dendritic cell, and granulocyte populations with greater precision in mouse tissues, both at steady-state and in disease or experimental conditions.

Clone M1/70 is a widely used monoclonal antibody targeting CD11b (integrin alphaM), with key findings in the scientific literature highlighting its central role in immunology, tumor biology, and inflammation research.

Key findings include:

• Broad utility in immunophenotyping and cell isolation:

  • M1/70 is used extensively in flow cytometry, immunoprecipitation, and immunohistochemistry (frozen tissue) to detect and quantify CD11b expression on murine myeloid cells, including macrophages, neutrophils, NK cells, and a subset of B cells.
  • It is also noted to be cross-reactive with human CD11b, useful for detecting this antigen on human monocytes, granulocytes, and NK cells.

• Blocking/functional assays:

  • M1/70 has been critical in studies examining CD11b function, notably its ability to block ligand binding (such as iC3b and fibrinogen) to the Mac-1 integrin, and to inhibit myeloid cell recruitment and adhesion in vitro and in vivo.
  • Functional grade M1/70 is used for assays requiring neutralization or inhibition of CD11b-mediated cellular functions, such as leukocyte migration and cell-cell adhesion.

• Role in tumor biology and angiogenesis:

  • Studies using M1/70 demonstrate that neutralizing CD11b reduces myeloid cell infiltration into irradiated tumors and enhances tumor response to radiotherapy, illustrating the importance of CD11b^+^ myeloid cells in tumor vasculature restoration and recurrence after irradiation.
  • This work highlights the functional relevance of CD11b in tumor microenvironment modulation and post-irradiation angiogenesis.

• Inflammation and cytokine response:

  • M1/70 injection can induce a pro-inflammatory response in Mac-1–expressing cells, especially in macrophages, leading to increased serum cytokines like IL-6, TNF-α, and MCP-1.

• Antibody characteristics and limitations:

  • M1/70 is not recommended for immunohistochemistry on formalin-fixed paraffin-embedded tissues, but is validated for immunofluorescence on frozen tissues and for in vitro and in vivo blocking studies.
  • Purity and performance characteristics have been validated: >90% by SDS-PAGE, <10% aggregation by HPLC, and tested for low endotoxin when used in cell culture or in vivo.

Summary Table: Main Applications and Key Insights

In summary, clone M1/70 is indispensable for dissecting myeloid cell biology, integrin function, inflammatory processes, and the tumor microenvironment. Its blocking ability allows not just for cell marking, but also for probing the functional consequences of CD11b inhibition in experimental systems.