Anti-Mouse CD115 (CSF-1R) [Clone AFS98] — Purified in vivo PLATINUM™ Functional Grade

Clone AFS98 is a rat monoclonal antibody that specifically targets the CSF1R (CD115) receptor on mouse cells, including monocytes, macrophages, dendritic cells, and osteoclasts. Common in vivo applications of this antibody in mice include:

• Macrophage Depletion: Clone AFS98 is used to deplete macrophages in mice, which helps in studying the role of macrophages in various biological processes and diseases.
• Neutralization and Blocking of CSF1R Signaling: The antibody is effective in blocking CSF1R signaling, which is crucial for the proliferation and differentiation of cells in the monocytic lineage.
• Functional Assays: It is used in various functional assays to study biological pathways affected by CSF1R signaling, such as bioanalytical PK and ADA assays.
• Flow Cytometry: The antibody can be used for flow cytometry to identify and analyze myeloid lineage cells.
• Cancer Research: Clone AFS98 is utilized in cancer research to study the role of macrophages in tumor environments.

Overall, clone AFS98 is a versatile tool for in vivo studies, particularly in immunology and oncology research.

Commonly used antibodies or proteins co-applied with AFS98 (anti-mouse CD115/CSF1R) in the literature include markers for macrophage identification, myeloid/immune subset analysis, and isotype controls.

Key antibodies and proteins used with AFS98:

• F4/80: A classic marker for murine macrophages, frequently used to label macrophage populations by immunohistochemistry (IHC) and flow cytometry alongside AFS98 to dissect myeloid compartments.
• CD163: Another macrophage marker, more specific for M2-type (alternatively activated) macrophages. Used in combination with AFS98 to characterize macrophage polarization states.
• Isotype Controls (e.g., Rat IgG2a): Used as negative controls to assess antibody specificity, especially in immunophenotyping or blocking studies.
• CSF-1 (M-CSF, the ligand for CD115): Sometimes used in binding or blocking assays, or to detect increases in serum CSF-1 following AFS98 treatment as a pharmacodynamic readout.

Other frequently co-used antibodies and markers:

• Ly6C, Ly6G: To distinguish monocyte and granulocyte subsets.
• CD11b, CD11c: Markers of myeloid lineage to further classify macrophage and dendritic cells.
• CD45: Pan-leukocyte marker for gating immune populations in multi-color flow cytometry panels.
• Lineage cocktail markers (e.g., Ter119, B220, CD3, NK1.1, etc.): For exclusion of non-myeloid leukocytes in immunophenotyping panels.

These combinations are especially common in:

• Macrophage depletion or tracking studies.
• Tumor microenvironment and inflammation models.
• Phenotyping of tumor-associated macrophages (TAMs) or myeloid-derived suppressor cells.

The frequent use of F4/80 and CD163 alongside AFS98 is documented in both experimental protocols and commercial antibody datasheets, reflecting their central role in myeloid cell characterization in murine models.

Clone AFS98 is a monoclonal antibody targeting mouse CSF-1R (CD115), widely cited in scientific literature for its role in depleting macrophages and blocking CSF-1R signaling in vivo. The key findings from studies using AFS98 can be summarized as follows:

• Macrophage depletion: Administration of AFS98 leads to robust depletion of monocytes/macrophages, including both total F4/80+ and CD163+ M2-polarized subsets, in various murine tissues and tumor models. Dendritic cells and neutrophils remain largely unaffected.
• Tumor growth inhibition: Depleting tumor-associated macrophages (TAMs) using AFS98 disrupts the protumoral microenvironment and inhibits tumor growth in mouse models.
• Elevation of circulating CSF-1: Treatment with AFS98 increases serum CSF-1 levels, a consequence of blocking CSF-1 clearance by CD115-mediated endocytosis.
• Mechanism of action: Macrophage depletion is primarily due to blockade of CSF-1R signaling, rather than complement-dependent cytotoxicity or antibody-dependent cell-mediated cytotoxicity (ADCC); AFS98 is equally effective in mice deficient for C3 or FcγR.
• Effects on bone biology: AFS98 is as potent as bisphosphonates in reducing osteoclast numbers and bone lesions, highlighting its role in osteoclast differentiation and activity.
• Research tool: AFS98 is frequently used for flow cytometry to identify or deplete myeloid lineage cells, and as a functional blocking/neutralizing antibody in vitro and in vivo.

Additional context:

• CSF-1R/CD115 is a receptor for colony-stimulating factor 1 (CSF-1), regulating monocyte/macrophage, dendritic cell, and osteoclast proliferation and differentiation.
• The antibody has enabled investigation into myeloid cell biology, cancer microenvironments, bone remodeling, and immune modulation.

In summary, clone AFS98 is a validated tool for selectively depleting CSF-1R+ cells, dissecting macrophage functions in immunological and cancer biology, and modulating osteoclast-mediated bone resorption in preclinical mouse models.

Dosing regimens for clone AFS98—an anti-mouse CD115 (CSF-1R) monoclonal antibody—vary considerably by mouse model and study objective, but several patterns are evident:

• In tumor immunology models, doses typically range from 1.5 mg/mouse (~75 mg/kg) to as much as 50 mg/kg, often administered by intraperitoneal (IP) injection every 2-3 days.
• For syngeneic tumor models, a common protocol is 1.5 mg/mouse (usually corresponding to about 75 mg/kg if using 20 g mice), but higher doses from 25–50 mg/kg are used in other tumor settings and for more robust macrophage or monocyte depletion.
• In a detailed study, 50 mg/kg IP was given 3 times per week for 3 weeks, with significant biological effects on macrophage depletion and tumor progression.
• Some protocols administer 20 mg/kg IP every 3 days, particularly around day 5 post-tumor implantation.
• In metabolic disease models (e.g., obese db/db mice), dosing has included 25 mg/kg IP every second day for 6 weeks.

Key considerations:

• Dose and frequency are often tailored to model type (metabolic vs. cancer), the desired degree of macrophage depletion, and therapeutic endpoints.
• Duration and starting point (e.g., after tumor implantation, or at specific disease stages) further distinguish regimens.
• Optimal dosing often requires titration, as suggested by vendors and observed in pharmacodynamic studies, particularly for achieving robust CSF-1R saturation and depletion of target cell populations.

Summary:
Regimens with AFS98 range from low (1.5 mg/mouse) to high (50 mg/kg) doses, given every 2–3 days for periods of several weeks, with individual protocols depending on the specific disease model and research aim.