Anti-Mouse CD278 (ICOS) [Clone 7E.17G9] – Purified in vivo GOLD™ Functional Grade

Clone 7E.17G9 is most commonly used in vivo in mice as a blocking monoclonal antibody to inhibit the interaction between ICOS (Inducible T-cell Co-Stimulator, CD278) and its ligand ICOSL, thereby modulating T-cell activation and immune responses.

Key in vivo applications include:

• Blocking ICOS–ICOSL interaction: 7E.17G9 is widely used to interfere with costimulatory signaling in immune cells during mouse experiments, particularly to assess the role of ICOS in regulating T-cell function, immune activation, and tolerance.
• Analysis of immune modulation: Studies utilize 7E.17G9 to dissect the role of ICOS in autoimmune disease models, infectious disease response, transplantation, and tumor immunology by administering the antibody to living mice and observing changes in immune cell activity or disease progression.
• Maintenance of regulatory T cell homeostasis: ICOS signaling is important for regulatory T cell function; in vivo blockade with 7E.17G9 can help test this pathway’s physiological importance.
• Functional studies of humoral immunity: Because ICOS is critical for T-dependent B cell responses (e.g., germinal center formation, antibody production), blocking antibodies like 7E.17G9 are used to investigate these processes in vivo.

Additional relevant details:

• 7E.17G9 is validated for functional blocking assays, distinguishing its use from purely analytical/flow cytometric antibodies that are limited to phenotyping or quantitation.
• Secondary uses include in vivo investigation of ICOS’s role in Th2 cell development, signaling, and proliferation.

In summary: the predominant in vivo application of clone 7E.17G9 in mice is to functionally block the ICOS–ICOSL pathway, allowing detailed investigation of T cell–dependent immune mechanisms, regulatory T cell homeostasis, and humoral immune responses.

The 7E.17G9 antibody targets mouse ICOS (CD278), a key T cell costimulatory receptor, and is commonly used in immunology research alongside other markers to profile immune cell phenotypes and functions. The most frequently used antibodies or proteins in combination with 7E.17G9 include:

• CD28 and CTLA-4 antibodies: Both are structurally and functionally related to ICOS, serving as prototypical costimulatory and coinhibitory molecules, respectively, in T cell activation studies. They are often analyzed in parallel with ICOS to delineate costimulatory signaling networks.
• PD-1 (Programmed Death-1) and PD-L1: Regularly co-stained in flow cytometry panels or functional studies to assess T cell activation and exhaustion states.
• OX40 (CD134): Another member of the TNFR superfamily involved in T cell costimulation, sometimes used to map T cell subsets or assess responses alongside ICOS.
• CD3 and CD4/CD8: Core for identification of T cell populations (total, helper, and cytotoxic T cells) when gating on ICOS+ subsets.
• Granzyme B, Ki67: To evaluate cytotoxic activity and proliferation of T cells expressing ICOS, especially in tumor or infection models.
• CD16, CD56, HLA-DR, S100, PanCytokeratin: Used in broader immunophenotyping, especially in tumor tissue panels to distinguish immune and non-immune cells when assessing ICOS+ cells by immunofluorescence.
• Germinal center B cell markers (e.g., B220, CD19, GL7) and B7h/B7RP-1 (ICOS ligand): In studies of humoral immunity and follicular helper T cells, as ICOS is pivotal in Tfh function and B cell help.
• AKT, phospho-AKT, GSK3β, phospho-GSK3β: Used in signaling pathway analyses involving ICOS-mediated effects in T cells.

Summary Table: Common Antibodies/Proteins Used with 7E.17G9

Context and Relevance:
The routine use of these antibodies reflects the experimental need to:

• Distinguish costimulation pathways (ICOS vs. CD28/CTLA-4)
• Assess T cell function (activation, exhaustion, proliferation)
• Perform multicolor flow cytometry or immunofluorescence to precisely map ICOS-expressing cell subsets and their interaction partners.

This pattern is consistent across studies investigating autoimmunity, cancer, vaccine response, and germinal center reactions.

Clone 7E.17G9 is a monoclonal antibody targeting the Inducible T-cell Co-Stimulator (ICOS), a protein crucial for T cell activation and proliferation. The key findings from citations involving this clone in scientific literature include:

Applications and Functions

• Flow Cytometry: The 7E.17G9 antibody is widely used for flow cytometric analysis to detect ICOS expression on activated T cells in mouse models.
• Agonistic vs. Blocking Activity: Despite being reported as a blocking antibody, 7E.17G9 exhibits agonistic properties, enhancing AKT phosphorylation in T cells, suggesting its potential to activate ICOS signaling.
• ImmunoPET Imaging: The clone is used in immunoPET studies to visualize activated T cells in murine models, showing increased tracer uptake in the spleen and lymph nodes of mice with graft-versus-host disease (GvHD).

Therapeutic and Biological Insights

• Antitumor Activity: In tumor studies, an Fc-engineered version of 7E.17G9 showed antitumor efficacy by enhancing CD8+ T cell infiltration and reducing T regulatory cells in the tumor microenvironment.
• Immune Modulation: ICOS plays a role in promoting IL-17 synthesis in colonic intraepithelial lymphocytes, and the use of 7E.17G9 has been explored to modulate such immune responses.

Experimental Dosages and Formats

• Dosages: For antitumor studies, the antibody was administered at doses of 0.5, 5, and 10 mg/kg, demonstrating dose-dependent plasma concentrations.
• Formats and Conjugates: Available in various formats, including PE and PE-Cyanine7 conjugates for flow cytometry applications.

Dosing regimens of clone 7E.17G9 (anti-mouse ICOS) vary by application and mouse model, but commonly involve intraperitoneal (i.p.) injection of 100 µg/mouse per dose, with dosing intervals and frequency adjusted per experimental design.

Key published regimens and variations include:

• 100 µg/mouse i.p. injection, 3 doses: starting 2 days post-irradiation, then on days 6 and 9 post-irradiation (total 3 injections), in tumor-bearing mice (MC38 model).
• Product datasheets and suppliers cite this 100 µg/mouse i.p. dose as the reference for most in vivo studies, noting that alternative regimens may exist and the interval/frequency can be model-specific.
• Other published sources indicate that dose titrations in preclinical studies may range from 1, 5, 20, 100, up to 200 µg or mg per mouse, depending on whether the focus is on toxicity, efficacy, or synergistic effects with co-treatments. However, 100 µg/mouse remains standard in most immune-oncology research.

For flow cytometry or in vitro cell staining:

• Lower doses, such as 0.2–0.4 µg per 10^6 cells, are used for ex vivo or in vitro applications.

Dosing frequency and interval:

• In many preclinical tumor models, immune checkpoint inhibitors like 7E.17G9 are administered every 2–3 days for at least 2 weeks.
• Some regimens coordinate dosing with other interventions (e.g., immunotherapy or irradiation), starting 1–2 days post-treatment.

Model-specific variations:

• The timing and number of doses may be adjusted for differences in tumor growth kinetics, immune response dynamics, and combination with other therapies. Authors frequently reference pilot titrations, or select intervals (e.g., twice per week or in tandem with irradiation/other antibody treatments).

Summary table:

The 100 µg/mouse i.p. dose is the most consistently reported starting point for in vivo mouse studies using clone 7E.17G9, though frequency, total number of doses, and timing are adapted depending on mouse strain, tumor model, and co-treatments. If your specific mouse model or disease context differs substantially (e.g., immunodeficient strains, non-tumor studies), reviewing published protocols for your model is recommended.