Anti-Mouse NK1.1 [Clone PK136] — Purified in vivo PLATINUM™ Functional Grade

In Vivo Use of PK136 Clone in Mouse Studies

Clone PK136 is a widely utilized monoclonal antibody specific for mouse NK1.1 (CD161), a cell surface glycoprotein expressed primarily on natural killer (NK) cells and certain T-cell subsets in select mouse strains such as C57BL/6, FVB/N, and NZB, but not in strains like BALB/c or AKR.

Main Applications

• NK Cell Depletion: The primary in vivo application of PK136 is the targeted depletion of NK cells in mouse models to investigate the role of NK cells in immunity, cancer, infection, and other diseases. This is achieved through intraperitoneal (i.p.) injection of the antibody, which binds to NK1.1-expressing cells, leading to their elimination via antibody-dependent cytotoxicity or complement-mediated lysis.
• Functional Studies: Beyond depletion, PK136 has also been used to activate NK cells in vitro, although its in vivo use is predominantly for depletion.

Dosing and Administration

• Standard Protocol: A typical regimen involves a single i.p. injection of 200 ?g per mouse for acute NK cell depletion.
• Sustained Depletion: For prolonged effects, repeated doses (e.g., 200 ?g every 3–5 days) or an initial higher dose (250 ?g) followed by maintenance doses (100–150 ?g every 3–5 days) can be used, depending on the experimental needs and mouse strain.
• Optimization: The exact dosing schedule should be empirically determined for each study, as efficacy can vary with strain, age, and specific experimental conditions.

Specificity and Limitations

• High Specificity: PK136 is highly specific for NK1.1+ cells, minimizing off-target effects compared to broader depleting antibodies like anti-asialo GM1.
• Strain Dependency: Effectiveness is limited to mouse strains that express the NK1.1 antigen; it does not work in strains such as BALB/c or AKR, where NK1.1 is absent.
• Functional Heterogeneity: PK136 may recognize both activating (NKR-P1C/CD161c) and inhibitory (NKR-P1B/CD161b) isoforms in some strains, introducing potential complexity in interpreting functional outcomes.

Research Impact

PK136-mediated NK cell depletion has been instrumental in elucidating the role of NK cells in host defense, tumor surveillance, and immune regulation. Its use is well-documented in peer-reviewed studies, including recent work (e.g., Wang et al. 2022).

Summary Table: PK136 In Vivo Use

Key Considerations

Researchers must validate the expression of NK1.1 in their mouse models before using PK136, and optimize the dosing regimen based on preliminary experiments. While PK136 is a powerful tool for in vivo NK cell depletion, alternative antibodies (e.g., anti-asialo GM1, anti-CD49b/DX5) should be considered for strains lacking NK1.1 expression.

References in Practice

For detailed protocols and product availability, researchers often consult core facilities or commercial suppliers, and refer to foundational literature such as Koo and Peppard (1984) and Reichlin and Yokoyama (1998).

Commonly Used Antibodies and Proteins with PK136 in the Literature

The PK136 antibody, specific for mouse NK1.1 (CD161b/c), is a mainstay for identifying and manipulating natural killer (NK) cells in certain mouse strains, notably C57BL/6, FVB/N, NZB, and others. Researchers frequently use it in combination with other antibodies or proteins to either corroborate findings, target additional NK cell markers, or serve as experimental controls.

Key Companion Antibodies

DX5 (anti-CD49b):
DX5 is another widely used monoclonal antibody that recognizes the CD49b integrin subunit (also known as pan-NK cell marker in mice). It is often used alongside PK136 to confirm NK cell identity and depletion, especially because not all mouse strains express NK1.1. Fluorescence-activated cell sorting (FACS) analysis using both PK136 and DX5 can provide more comprehensive identification and quantification of NK cells, as seen in depletion experiments where PK136 was the primary depletion agent and DX5 was used for verification.

Anti-Asialo GM1:
This polyclonal antibody targets the asialo-GM1 glycolipid expressed on the surface of mouse NK cells and some activated T cells. It is frequently used for in vivo NK cell depletion in mouse models, sometimes as an alternative or in parallel with PK136.

Anti-NKp46 (clone 29A1.4):
NKp46 is a highly specific marker for NK cells in both mice and humans. The 29A1.4 clone is used to target NKp46 in various species, providing an additional means to identify NK cells in experimental setups.

Experimental Controls and Other Proteins

Mouse IgG2a Isotype Control (clone 5D11):
In studies involving PK136, an isotype-matched control antibody (e.g., clone 5D11, which binds human carcinoembryonic antigen and does not react with mouse tissues) is often administered to control for non-specific effects of antibody treatment.

Toll-like Receptor Ligands (e.g., LPS):
In some immunological experiments, researchers use bacterial ligands such as lipopolysaccharide (LPS), a Toll-like receptor 4 (TLR4) agonist, to stimulate immune responses, sometimes in the context of NK cell studies.

Summary Table: Common Companion Antibodies/Proteins for PK136

Conclusion

PK136 is rarely used in isolation. The most common companion antibodies are DX5 (for comprehensive NK cell identification), anti-asialo GM1 (for NK cell depletion), and anti-NKp46 (for cross-species NK cell studies). Appropriate isotype controls and stimulatory ligands like LPS are also documented in the literature, depending on the experimental design. These combinations enhance the specificity and interpretability of NK cell research in mice.

Clone PK136 has been instrumental in advancing our understanding of natural killer (NK) cells and their biology through several decades of research. The antibody was originally developed in 1984 and has since become a cornerstone tool for NK cell research.

Establishment and Characterization

The foundational work by Koo and Peppard in 1984 established the monoclonal anti-NK1.1 antibody clone PK136, demonstrating its specificity for the NK1.1 antigen expressed on natural killer cells. This breakthrough provided researchers with a reliable tool to identify and study NK cells in laboratory settings.

NK Cell Differentiation Studies

A significant finding came from Koo et al. in 1986, who used PK136 to study NK cell differentiation in NK1.1(-) mouse models. This research revealed important insights into how NK cells develop and mature, establishing the foundation for understanding NK cell ontogeny. The study demonstrated that NK1.1 expression serves as a marker for specific stages of NK cell development and functional capacity.

NK Cell Proliferation and Activation

Reichlin and Yokoyama's 1998 research uncovered that NK cell proliferation could be induced by anti-NK1.1 antibodies (including PK136) in combination with IL-2. This finding was crucial for understanding how NK cells can be stimulated to expand in vitro and provided insights into the signaling pathways involved in NK cell activation and growth.

Inhibitory Receptor Function

The work by Kung et al. in 1999 revealed that the NKR-P1B gene product functions as an inhibitory receptor on SJL/J NK cells. This research contributed to understanding the complex balance between activating and inhibitory signals that regulate NK cell function, highlighting the sophisticated mechanisms that control NK cell cytotoxicity.

Strain-Specific Expression Patterns

Research using PK136 has consistently demonstrated that NK1.1 expression varies significantly between mouse strains. The antibody effectively identifies NK cells in certain strains including CE, C57BL/6, FVB/N, and NZB, while NK1.1 is absent from NK cells in other strains such as 129, A, AKR, BALB/c, C3H, CBA, and SJL. This strain-specific expression pattern has important implications for experimental design and interpretation of NK cell studies.

Applications in Functional Studies

Clone PK136 has proven highly effective for in vivo NK cell depletion studies, providing researchers with a powerful tool to investigate NK cell function in disease models. The antibody's high specificity for NK cells reduces off-target effects, while its efficiency in depleting NK cells allows for precise experimental results across various in vivo models and experimental setups.

Multi-Modal Analysis Capabilities

The versatility of PK136 extends to multiple experimental applications, including flow cytometry analysis where it can distinguish between NK1.1+ CD3e- NK cells and NK1.1dim CD3e+ NK-T cells. This capability has been essential for characterizing different lymphocyte populations and understanding the heterogeneity within the NK cell compartment and related cell types like NKT cells.

These collective findings have established clone PK136 as an indispensable research tool that has significantly advanced our understanding of NK cell biology, from basic developmental processes to complex functional interactions in health and disease.

Dosing regimens of the anti-NK1.1 antibody clone PK136 in mouse models typically range from 200–500??g per mouse per dose, usually administered intraperitoneally, with both single and repeated dosing schedules used depending on experimental aims and mouse strain.

Key dosing strategies and variations documented across mouse models:

• Standard single dose: 200??g per mouse via intraperitoneal injection is frequently used for acute NK cell depletion.
• Repeated doses for sustained depletion: 200??g per mouse administered every 3–5 days (1–3 times per week) is common for continued NK cell suppression, especially in immunological or tumor studies.
• Initial high-dose + maintenance: Protocols may use an initial higher dose (250??g/mouse), then follow with maintenance doses of 100–150??g every 3–5 days, which can be useful for longer-term depletion or in models where NK cells display rapid recovery.
• Higher-dose regimens: Some studies administer 500??g per mouse intraperitoneally three times per week for robust and prolonged NK and NKT cell depletion, confirmed by flow cytometry.

Regimen examples from published studies:

Details on mouse strain specificity:

• NK1.1 (CD161/NKR-P1C) is only expressed in select strains (notably C57BL/6, SJL, FVB/N, NZB/W), so PK136 is only effective in strains with the NK1.1 epitope.
• In strains lacking NK1.1, alternative depletion strategies (e.g., anti-asialo GM1) are necessary.

Experimental considerations:

• Efficiency and safety of depletion may vary by mouse age, strain, and immune status.
• Repeated administration can induce anti-rat antibody responses (since PK136 is of rat origin), sometimes reducing depletion efficacy in prolonged studies.
• Always confirm depletion by flow cytometry or appropriate functional assays, as efficacy may drop with time or differ by tissue.

Summary of core regimens:

• Single-dose: 200??g i.p. for transient depletion.
• Repeated/sustained depletion: 200–300??g i.p., 1–3?×?per week, or 500??g i.p. 3×/week for high-demand models or prolonged protocols.
• Maintenance protocol: Start with 250??g i.p., then 100–150??g every 3–5 days for extended experiments.

The most common regimens cluster around 200–300??g/mouse via intraperitoneal injection at an interval matching the experimental need for NK cell depletion, typically in C57BL/6 background mice.