Rat IgG₁ Isotype Control [Clone GL113] — Purified in vivo GOLD™ Functional Grade

Clone GL113 is most commonly used in mice as an in vivo rat IgG1 isotype control antibody. Its primary application is to serve as a negative control in immunological experiments, specifically to distinguish between specific effects of an experimental antibody and nonspecific background effects due to the antibody isotype, Fc interactions, or dosing regimen.

Key in vivo uses in mice include:

• Isotype Control: GL113 is used alongside experimental monoclonal antibodies that are of the rat IgG1 isotype. It allows investigators to control for nonspecific effects (such as Fc receptor binding or immune complex formation) that could be caused by any rat IgG1 antibody irrespective of its antigen specificity.
• Validation of Specificity: By comparing animals treated with GL113 to those treated with the antibody of interest, researchers confirm that any observed biological changes are due to the experimental antibody’s target binding and not unrelated effects of the antibody isotype itself.
• Negative Control in Functional Studies: Used in protocols assessing cytokine levels, immune cell depletion, activation, or in vivo antibody delivery, to ensure that changes are not due to generic antibody effects.

GL113 is not designed for therapeutic or direct targeting of mouse proteins but is strictly a control reagent. Despite older literature associating the designation GL113 with anti-IL-4 activity, modern commercial sources and standard usage specify it as an isotype control without known mouse reactivity, distinguishing it from functional anti-IL-4 clones such as 11B11.

When selecting an in vivo isotype control for mouse studies (e.g., cancer, infection, or immunology models), GL113 is chosen whenever the primary antibody is a rat IgG1, due to its matched subclass and minimal cross-reactive effects.

No evidence from current standard references supports a common use of GL113 in vivo as a depleting or neutralizing antibody in mice; its application is nearly universally as an isotype control.

Commonly Used Antibodies or Proteins Alongside GL113

GL113 is a rat IgG1 isotype control antibody, primarily used as a negative control in experiments—especially in mouse in vivo studies—to help distinguish specific effects of experimental antibodies from non-specific or background effects. While GL113 itself is an isotype control, it is often used alongside other experimental antibodies or proteins designed to target specific biological pathways. However, detailed literature on specific combinations of GL113 with other antibodies/proteins is limited in the provided search results.

Antibodies Commonly Used in Experimental Protocols Similar to GL113

• Anti-IL-13 Antibodies: Researchers sometimes use anti-IL-13 antibodies in conjunction with GL113 or similar isotype controls, particularly when investigating Th2-type immune responses. This is because IL-4 and IL-13 share receptor complexes and have overlapping biological functions; blocking both cytokines may be necessary to fully inhibit Th2 responses. However, direct evidence of GL113 being used specifically with anti-IL-13 in a single experiment is not detailed.
• GLP-1 Receptor (GLP-1R) Antibodies: The search results discuss various GLP-1R-targeting antibodies in the context of GPCR antibody discovery, but there is no indication that these are routinely co-used with GL113. The mention of GLP-1R antibodies is provided as an example of high-interest, functionally validated antibodies, but not in direct combination with GL113.
• Other Isotype Controls: In general, isotype controls like GL113 are used alongside experimental antibodies targeting specific antigens. The choice of experimental antibody depends entirely on the research question (e.g., anti-CD3, anti-CD28, anti-cytokine antibodies), but the search results do not specify particular combinations with GL113.

Proteins and Biological Molecules

• Cytokines (e.g., IL-4, IL-13): These are often the targets of experimental antibodies in studies where GL113 serves as a control, but again, they are not "used with" GL113 in the sense of being co-administered; rather, their effects are studied independently, using GL113 as a negative control.
• Beta-galactosidase: GL113 is an anti-beta-galactosidase antibody, but it is used as an isotype control rather than as a functional reagent. In experimental design, beta-galactosidase itself would not typically be co-used with GL113.

Summary Table

Key Points

• GL113 is almost exclusively used as a negative isotype control in antibody-based experiments, especially in vivo.
• Anti-IL-13 antibodies are mentioned as commonly used in related experimental contexts, but there is no explicit evidence that they are routinely combined with GL113 in the same experiment.
• Other experimental antibodies (targeting cytokines, cell surface markers, etc.) are used in parallel with isotype controls like GL113, but the specific combinations depend entirely on the research question and are not detailed in the provided literature.
• No proteins or cytokines are directly co-administered with GL113; rather, GL113 serves as a benchmark for non-specific effects while other antibodies target specific molecules.

In summary, while GL113 is a standard isotype control, the specific experimental antibodies or proteins used alongside it are dictated by the biological pathway under investigation—most commonly, these include antibodies against cytokines like IL-13 in immunology studies, but direct evidence of co-usage is not provided in the search results.

Clone GL113 is a rat IgG1 monoclonal antibody that has been extensively utilized in scientific research, primarily serving as an isotype control antibody in experimental studies. The key findings from its citations in scientific literature reveal its important role in validating experimental results across multiple research domains.

Primary Function as Isotype Control

GL113 specifically targets beta-galactosidase but is most commonly employed as a negative control in in vivo mouse experiments. As an isotype control, it provides researchers with a critical baseline to distinguish specific antibody binding from non-specific background effects in immunological studies. This application is essential for ensuring the validity of experimental results when testing other antibodies with biological activity.

Applications in Immunological Research

The antibody has been referenced across diverse areas of biomedical research. In tumor immunology studies, GL113 served as a control antibody in experiments investigating dendritic cell paralysis reversal using CpG immunostimulatory sequences. The research utilized 5 μg/ml of the control rat IgG1 antibody to validate findings related to antitumor immune responses.

GL113 has also been applied in autoimmune disease research, particularly in studies examining inflammatory arthritis and dermatitis in thymectomized, CD25+ cell-depleted mice. In these experiments, both GL113 and PC61 antibodies were used as rat IgG1 standards in ELISA assays, with biotinylated anti-rat IgG1 (clone RG11/39.4) employed for detection purposes.

Use in Viral Research

More recently, GL113 has been utilized in SARS-CoV-2 research investigating ACE2 as the critical in vivo receptor. Studies administered the antibody at doses of 2 × 500 µg/200 µl as a control to validate findings about viral receptor interactions.

The widespread citation of GL113 across multiple research fields underscores its value as a reliable negative control, enabling scientists to confirm that observed effects are due to specific antibody-antigen interactions rather than non-specific binding or other confounding factors.

Dosing regimens for clone GL113—a rat IgG1 isotype control—vary substantially depending on the mouse model, experimental application, and administration route. The most widely reported protocol in tumor immunotherapy studies is 1 mg per mouse intraperitoneally (i.p.) every five days for six total doses, spanning about 30 days.

Additional dosing approaches have been documented for different study objectives:

• CD-1 Mouse Model, Pharmacokinetic Study: A single intravenous (i.v.) bolus dose of 5 mg/kg is administered, with blood sampling for up to 14 days to analyze pharmacokinetic parameters.
• Colitis Model (TNBS-induced): GL113 was administered at 5 mg/ml, i.p., once daily for 3 days.
• Oral Tolerance Studies: Control mice received undetailed GL113 dosing; the context implies standard i.p. use, aligning with the commonly used doses above.
• Detection/Duration Studies: GL113 and other antibodies become undetectable in mice approximately 21 days after administration, indicating its pharmacokinetic profile and suggesting dosing intervals that ensure presence during the experimental window.

Key variables influencing regimen:

• Mouse strain (e.g., CD-1 vs BALB/c)
• Study type (immunotherapy, colitis, tolerance)
• Administration route (i.p. is most common, but i.v. used for PK studies)
• Experimental duration and dose frequency (from daily injections over three days to every five days for a month)

Summary Table: GL113 Dosing Across Mouse Models

*Route inferred from standard practice.

In summary, 1 mg per mouse intraperitoneally every five days is the most typical regimen, but specific dosing schedules may change according to mouse strain, experimental design, and the intended scientific objective. Where precise regimens are lacking, investigators generally align with these established protocols unless pilot studies indicate alternative pharmacokinetics or efficacy requirements.