Mouse IgG_2a Isotype Control [Clone C1.18.4] — Purified in vivo GOLD™ Functional Grade

The C1.18.4 clone is extensively used in in vivo mouse studies as a critical negative control antibody to ensure the validity and accuracy of experimental results.

Primary Function as Isotype Control

The C1.18.4 clone serves as a mouse IgG2a isotype control that is specifically designed to have low or no specific binding to any mouse sample. This makes it an ideal non-reactive control for experiments using mouse IgG2a antibodies, allowing researchers to distinguish between specific antibody effects and non-specific background binding.

Applications in Mouse Studies

Negative Control Function: The primary application of C1.18.4 in mouse studies is as an isotype-matched negative control for mouse IgG2a kappa antibodies. Researchers inject this control antibody alongside their experimental antibodies to estimate the degree of non-specific binding and ensure that observed effects are truly due to the specific antibody being tested rather than general antibody-related effects.

Functional Assays: The clone is used in various functional assays within mouse models. This includes studies where researchers need to control for potential non-specific effects of antibody administration on mouse physiology or immune responses.

Comparative Studies: In experiments involving in vivo depletion studies, such as those targeting Gr-1+ myeloid cells, C1.18.4 serves as the control to demonstrate that effects are specific to the target antibody rather than general consequences of antibody injection.

Technical Specifications for In Vivo Use

The C1.18.4 clone is produced to meet stringent in vivo grade standards, including endotoxin levels of less than 1-2 EU/mg of protein and greater than 95% purity. It is formulated in PBS without preservatives and undergoes 0.2 ?m filtration to ensure sterility for animal injection. The antibody is produced in animal-free facilities using mammalian cell culture systems, making it suitable for sensitive in vivo applications.

Experimental Design Integration

Researchers typically use C1.18.4 as part of a controlled experimental design where one group of mice receives the experimental mouse IgG2a antibody while another group receives the C1.18.4 isotype control at equivalent doses. This allows for proper interpretation of results by accounting for any non-specific effects of antibody administration, injection stress, or general immune stimulation that might occur independently of the specific antibody-antigen interaction being studied.

C1.18.4 is a mouse IgG2a isotype control antibody frequently used in immunological research as a negative control, rather than for specific antigen targeting. In studies where C1.18.4 is employed, it is most often paired with functionally relevant mouse IgG2a antibodies against specific targets, allowing clear discrimination of specific vs. nonspecific (background) effects.

Commonly used antibodies or proteins in experiments alongside C1.18.4 include:

• Mouse IgG2a antibodies against cell surface markers or antigens, such as anti-MHC class I antibodies (e.g., 34-1-2S, SF1.1.10, AF6-88.5.5.3). These antibodies are commonly assessed for their biological effects, while C1.18.4 serves as a control in parallel.
• Other IgG isotype controls or subclasses (e.g., MOPC-173, another mouse IgG2a isotype control). These may be included to match subclasses of experimental antibodies.
• Complement proteins, such as C1q, are sometimes analyzed for their interaction with antibodies in functional assays (for example, complement activation ELISAs).
• Cellular markers or antibodies relevant to the experimental system, such as anti-HLA, anti-CD20, or anti-CD37 antibodies, particularly in studies examining immune activation or complement pathways.

In summary, C1.18.4 is nearly always used in combination with:

• Experimental monoclonal antibodies of mouse IgG2a isotype (against a specific antigen).
• Other isotype-matched controls to properly assess background responses.
• Occasionally, with detection reagents or functional protein partners (such as C1q) when investigating mechanisms like complement activation.

These combinations allow accurate interpretation of in vivo or in vitro immunology and cell biology studies using monoclonal antibodies.

Clone C1.18.4 is a widely used mouse IgG2a isotype control antibody in immunological research, primarily to serve as a negative control for experiments such as flow cytometry and in vivo depletion studies, ensuring that observed effects are due to specific antibody-antigen interactions rather than nonspecific binding or Fc-mediated actions.

Key findings and uses of clone C1.18.4 in the scientific literature, based on source citations:

• Standard Isotype Control: C1.18.4 is employed as a control antibody that matches the isotype, subclass, and species of the primary antibody, but does not bind any known antigen in the host system. This is critical for establishing background staining and non-specific effects in experiments like flow cytometry, antibody-dependent assays, and immune cell depletion.

• Reduced Fc-mediated Effector Function (LALA-PG variant): The LALA-PG mutant form of C1.18.4 contains point mutations in the Fc region, designed to abrogate binding to Fc gamma receptors (Fc?R) and C1q, thus eliminating or minimizing antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement activation. This variant is particularly useful in experiments where it is essential to verify that observed biological effects are not due to Fc interactions.

• Minimal Cross-reactivity: Extensive screening has validated that C1.18.4 does not cross-react with cells or tissues from mice, rats, or humans, making it a reliable negative control.

• Applications in Literature:

  • C1.18.4 is commonly cited in peer-reviewed studies across immunology, oncology, and cell biology, particularly as an isotype control in experiments assessing antibody specificity and immune modulation.
  • Specific publications where C1.18.4 has been cited include those focusing on blood cell dynamics, mechanisms in arthritis, and cutaneous immunity, indicating its broad acceptance and reliability for comparative studies.

• Well-respected Controls: C1.18.4 is recommended and used by well-regarded commercial and academic sources for the calibration and validation of immunological assays.

• Not antigen-specific: Unlike antibodies targeting a specific antigen, C1.18.4 has "unknown specificity" or is purposely raised against an irrelevant antigen (e.g., keyhole limpet hemocyanin/KLH), removing confounding effects from target binding.

There are no specific findings regarding clone C1.18.4 itself (beyond these utility roles), as its primary use is experimental control rather than biological investigation. If more detail is required about a particular application (e.g., a cited study using C1.18.4), please clarify the context.

The dosing regimens for clone C1.18.4—a mouse IgG2a isotype control antibody—do not have universally fixed standards and often vary according to the mouse model, experimental design, and purpose of use. Available sources emphasize that C1.18.4 is primarily a negative control and its dosing is matched to the primary therapeutic or test antibody being studied, rather than being dictated by its own specific pharmacological profile.

Essential context:

• Common usage: C1.18.4 is used as a non-reactive, isotype-matched negative control to validate the specificity of immune interventions in in vivo and in vitro experiments across diverse mouse strains and disease models.
• Typical dosing pattern: Researchers generally administer C1.18.4 at the same concentration, route (e.g., intraperitoneal injection), and schedule as the experimental IgG2a antibody whose effects are being controlled for. For example, if the primary IgG2a antibody is given at 5 mg/kg twice per week IP, C1.18.4 will be administered identically unless otherwise justified by the study protocol.

Variability across models:

• Immuno-oncology models may involve dosing regimens of 5 mg/kg IP once or twice weekly, depending on tumor burden and experimental duration, mirroring therapeutic antibody dosing.
• Autoimmune or inflammation models typically use dosing schedules tied to disease induction timelines and matched to comparator antibody treatments.

Additional information:

• Preparation and purity controls (such as endotoxin level, sterility, and buffer formulation) are critical for minimizing non-specific effects irrespective of model type.
• No unique pharmacodynamics: C1.18.4 has no specific biological activity in mice beyond serving as a control, so its dosing is entirely controlled by the parameters of the test antibody or study needs.

In summary, dosing regimens for C1.18.4 in different mouse models are matched to the companion IgG2a antibody under investigation and are adapted to the specific study design; there is no standardized dose that applies across all models, but commonly used regimens reflect those of test antibodies in the same experiments.