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

The clone ICRF44 is a mouse monoclonal antibody specific for human CD11b (integrin alpha M, Mac-1, CR3), and is primarily used for the detection and functional study of human CD11b-expressing cells in in vitro applications such as flow cytometry and immunohistochemistry. It is not typically used for in vivo mouse studies because it is specific to human CD11b and does not react with mouse CD11b.

Key context and usage details:

• ICRF44 specifically recognizes human CD11b, not mouse CD11b. Its reactivity is validated for humans and a range of non-human primates (e.g., baboon, cynomolgus monkey, rhesus monkey), but not mouse.
• Application limitations: Suppliers and product documentation consistently state that ICRF44 is for research use only and specifically not for in vivo use. There are no reports, protocols, or validation data supporting its use for in vivo mouse studies.

Essential technical information:

• Research Applications: ICRF44 is widely used for staining and analysis via flow cytometry and immunohistochemistry in human cell samples, and is reported to block human monocyte adhesion and affect cytokine/chemokine release in vitro.
• Cross-reactivity: ICRF44 may cross-react with certain non-human primates and other mammals like pig, but not with mouse antigen.
• In vivo suitability: Product vendors explicitly advise against in vivo use, indicating that this antibody is intended for laboratory research only, not for animal experiments or therapeutic applications.

Unless "in vivo mouse studies" refers to engrafted human cells (e.g., humanized mouse models bearing human immune cells), ICRF44 would not be useful for monitoring mouse CD11b or mouse myeloid cells. If the intention is to study human CD11b expression in a mouse model where human cells are present, ICRF44 may be used for flow cytometric or histological analysis of those human cells ex vivo, but not for direct in vivo administration in mice.

In summary:
ICRF44 is not used to target or detect mouse CD11b in in vivo mouse studies. Its specificity is for human CD11b, making it suitable for in vitro assays or for detecting human cells in xenograft or humanized mouse models via ex vivo analysis, but not for in vivo use in conventional mouse studies.

The correct storage temperature for the sterile packaged monoclonal antibody clone ICRF44 is 2–8°C, and it should be protected from prolonged exposure to light; do not freeze this antibody.

For most manufacturers and formats:

• Store undiluted between 2°C and 8°C (standard refrigerator temperature).
• If provided lyophilized (freeze-dried), reconstitute as per instructions, and then store the reconstituted antibody at 2–8°C for up to 1 month, or at –20°C to –70°C for longer-term storage, as recommended by some suppliers for post-reconstitution storage.

Key additional details:

• Do not freeze liquid antibody unless manufacturer instructions specifically allow for it, as freeze-thaw cycles can denature the antibody and reduce activity.
• Avoid prolonged exposure to light, especially for fluorophore-conjugated versions (like FITC or AF488 conjugates).
• If supplied in aliquots, avoid repeated freeze-thaw cycles; aliquot as needed for short-term use at 2–8°C.

These guidelines are consistent across major suppliers of clone ICRF44, including BioLegend, Sigma-Aldrich, Proteintech, and Innov Research. Always check the specific datasheet for the product you received for any unique manufacturer recommendations.

Commonly Used Antibodies and Proteins with ICRF44 in the Literature

ICRF44 is a monoclonal antibody targeting the integrin ?M subunit (CD11b), widely used for detecting and studying immune cell populations, particularly monocytes, neutrophils, and macrophages. In scientific literature, ICRF44 is often employed alongside other antibodies and proteins pertinent to leukocyte biology and receptor function.

Antibodies Frequently Used with ICRF44

• Anti-CD18 (integrin ?2 subunit): CD11b (integrin ?M) pairs with CD18 (integrin ?2) to form the heterodimeric receptor Mac-1 (CR3), a key player in leukocyte adhesion and migration. Studies often use anti-CD18 antibodies alongside ICRF44 to assess the expression and function of the complete Mac-1 complex.
• Anti-CD14: Frequently co-stained with ICRF44 to distinguish monocyte subsets, particularly classical (CD11b+CD14+), intermediate (CD11b+CD14+CD16+), and non-classical (CD11b+CD14lo/dimCD16+) monocytes.
• Anti-CD16 (Fc?RIII): Used in combination with ICRF44 and CD14 to further characterize monocyte subsets and assess their functional phenotypes.
• Anti-HLA-DR: Often paired with ICRF44 to identify antigen-presenting cells such as macrophages and dendritic cells.
• Anti-CD45: A pan-leukocyte marker frequently used to identify total leukocyte populations in conjunction with ICRF44, which is specific to myeloid cells.
• Anti-Ly6G (in murine models): Used in mouse studies as a marker for neutrophils, analogous to CD11b+ in humans. ICRF44 is human/monkey/primate specific, so murine antibodies like Ly6G are used in parallel for cross-species comparisons.

Proteins and Ligands Relevant to CD11b Biology

• ICAM-1, ICAM-2, ICAM-3, ICAM-4: Endothelial adhesion molecules that interact with CD11b/CD18 (Mac-1), mediating leukocyte recruitment and transendothelial migration.
• Fibrinogen: A key extracellular matrix protein that binds to Mac-1 (CD11b/CD18), promoting cell-matrix adhesion and immune cell activation.
• Factor X: A coagulation factor that interacts with Mac-1, linking inflammation and coagulation pathways.
• iC3b: A complement fragment recognized by CD11b/CD18, enabling phagocytosis of complement-opsonized pathogens.
• CD66b (CEACAM8): An activation marker for neutrophils, sometimes used alongside ICRF44 to assess neutrophil activation states.

Typical Experimental Combinations

• Flow cytometry (FACS): ICRF44 is often used in panels with anti-CD14, anti-CD16, anti-CD45, and anti-HLA-DR to phenotype human leukocyte subsets.
• Functional assays: Investigations into adhesion and migration frequently employ ICRF44 with antibodies against ICAM-1 or fibrinogen to study cell-cell and cell-matrix interactions.
• Inflammation models: Co-staining with anti-Ly6G (mouse) or anti-CD66b (human) helps assess neutrophil recruitment and activation.

Summary Table: Key Combinations

These combinations reflect the literature’s focus on understanding leukocyte biology, adhesion, migration, and the role of integrin receptors in immune responses.

Clone ICRF44 is a widely cited monoclonal antibody targeting human CD11b (integrin ?M, also known as MAC-1 and CR3), a key cell surface glycoprotein involved in leukocyte adhesion, migration, and immune activation. Scientific literature using ICRF44 has yielded several key findings:

• Cellular expression and applications: ICRF44 detects CD11b on monocytes, granulocytes, NK cells, and some lymphocytes. It is also cross-reactive with non-human primates including Cat, Cynomolgus monkey, Baboon, and Rhesus monkey.
• Functional impact: ICRF44 can block adhesion of monocytes and is reported to stimulate cytokine and chemokine release, indicating its use in functional studies of immune cell activation and trafficking.

Key findings from cited literature:

• Mac-1 receptor clustering: Using ICRF44, studies have shown that clustering of the Mac-1 (CD11b/CD18) receptor on neutrophils initiates the production of pro-inflammatory extracellular vesicles, demonstrating the critical role of CD11b in the regulation of inflammation.
• Flow cytometry and cell identification: ICRF44 is commonly used in flow cytometry to characterize and enumerate CD11b-expressing cells in human samples, including clinical and research settings.
• Immunomodulatory studies: The antibody is an essential tool in studies investigating immune cell recruitment, particularly in inflammation and infection, as CD11b mediates both cell-cell and cell-matrix interactions that are crucial for leukocyte migration to inflammatory sites.

Summary of impact:

• ICRF44 citations consistently highlight its role in dissecting the molecular mechanisms of immune responses, particularly emphasizing cell adhesion, migration, and signaling in leukocytes.
• Its use in diverse systems—including cross-species studies—demonstrates its reliability and importance in translational immunological research.

There is no evidence of conflicting information on clone ICRF44’s specificity or function in the provided literature, and its reputation as a well-validated research tool is reflected by numerous citations and applications in high-impact immunology studies.