Anti-Human CD8a [Clone OKT-8] — Purified in vivo PLATINUM™ Functional Grade

Clone OKT-8 is a monoclonal antibody that specifically targets the human CD8α molecule. It is commonly used in humanized mouse models for several in vivo applications:

1. CD8+ T Cell Depletion: OKT-8 is used to deplete human CD8+ T cells in humanized mice. This is particularly useful for studying human immune responses and interactions within a mouse model.

2. Immunological Studies: The antibody helps in studying the role of CD8+ T cells in various immunological processes, such as cytotoxic T cell functions and immune responses.

3. Cancer Research: OKT-8 may be employed in cancer research to investigate the role of CD8+ T cells in tumor immunity and to develop strategies for enhancing anti-tumor responses.

4. Vaccine Efficacy: It can be used to evaluate the impact of vaccines on CD8+ T cell responses in humanized mouse models.

While OKT-8 is specifically designed for human CD8α, other clones like 2.43 or YTS 169.4 are used for targeting mouse CD8α in non-humanized mouse models.

Commonly used antibodies or proteins alongside OKT-8 (an anti-human CD8α monoclonal antibody) in the literature include other lineage and functional markers for T-cell subset identification, as well as alternative anti-CD8 clones for comparison or multiplexing.

Key antibodies and proteins often used with OKT-8:

• Anti-CD3 (OKT3): Marks total T cells and is widely used with OKT-8 to distinguish CD8+ from other T-cell subpopulations.

• Anti-CD4 (OKT4): Identifies helper/inducer T cells, used in combination to define CD4+ and CD8+ populations and subsets.

• Other anti-CD8 clones: Often used for cross-validation or multiplex flow cytometry, such as:

  • SK1
  • MCD8
  • 32/M4
  • C8/144B
  • DK25
  • 2ST8.5H7 (anti-CD8β, sometimes used alongside OKT-8 which is specific for CD8α).

• Anti-CD8β (such as clone 2ST8.5H7): To distinguish between CD8αα and CD8αβ expressing cells, often paralleling OKT-8 staining.

• MHC class I tetramers: Used to detect antigen-specific CD8+ T cells, frequently with OKT-8 to facilitate identification of specific TCR-pMHC interactions.

• NK cell markers (e.g., CD16, CD56): Sometimes included when labeling CD8+ populations that might contain NK or NKT cells.

Besides antibodies, surface markers and functional stains such as those for activation (CD69, HLA-DR), exhaustion (PD-1), proliferation (Ki-67), or cytokine production are commonly multiplexed with OKT-8 in immunophenotyping panels.

In summary, the most commonly paired antibodies with OKT-8 are anti-CD3 and anti-CD4, as well as other anti-CD8 clones (SK1, DK25, 2ST8.5H7) and functional or phenotypic markers relevant to the specific immune cell subset or functional study.

The monoclonal antibody clone OKT-8 (OKT8) is a widely used reagent in immunology research, primarily for identifying and characterizing human CD8+ T cells through flow cytometry and other assays. Major findings about OKT8 from the scientific literature include:

• Specificity and Functional Effects:

  • OKT8 is specific for the CD8α molecule, a marker for cytotoxic T cells and certain thymocytes.
  • Unlike some other anti-CD8 antibodies, OKT8 can activate CD8+ T cells and trigger chemokine release (such as MIP-1α, MIP-1β, and RANTES) in these cells, indicating it can deliver an activation signal.
  • This stimulatory effect appears to be CD8+ T-cell-specific; OKT8 does not activate CD4+ T cells.

• Enhanced Detection and Staining:

  • Preincubation with OKT8 enhances the staining intensity of peptide-MHCI (pMHCI) tetramers, improving the identification of antigen-specific CD8+ T cells, especially those with weak TCR/pMHCI affinity (commonly observed in tumor or autoimmune responses).
  • Other anti-CD8 antibodies may hinder tetramer staining, but OKT8 increases both the quality and the number of detected antigen-specific events for low-affinity TCRs.

• Phenotyping and Clinical Research Usage:

  • OKT8 has been instrumental in longitudinal immunophenotyping studies, such as those tracking changes in circulating OKT8+ cells (CD8+ T cells) in multiple sclerosis (MS) patients versus controls.
  • Fluctuations in OKT8+ cell counts were observed independent of circadian rhythm or individual infectious exposures, but HLA-DR2 positivity was correlated with periodic reductions in OKT8+ cells, suggesting roles for both genetic (HLA) and environmental factors in determining CD8+ T-cell phenotypes in MS.

• Technical Application Notes:

  • OKT8 is validated for use in flow cytometry across different fluorophore conjugates (e.g., Alexa Fluor 488, PE, APC), enabling multi-parametric immune cell analysis.
  • The antibody has been tested and recommended for standardized protocols and is considered a reference clone for CD8 detection in humans.

• Limitations and Cross-Reactivity:

  • OKT8 does not react with CD4+ T cells or bind to CD8 antigens on non-human cells in several animal models.
  • No major non-specific binding has been reported, and OKT8 generally does not recognize CD8 molecules from species other than human.

Summary Table: OKT8 in Scientific Literature

These findings establish clone OKT8 as both a phenotyping antibody and a functional tool, allowing more sensitive detection and analysis of antigen-specific CD8+ T cells in both basic and clinical research.

The OKT-8 antibody, which targets the human CD8α molecule, is not typically used in standard mouse models but is often utilized in humanized mouse models. Humanized mouse models are designed to mimic human immune responses more closely than traditional mouse models. However, specific dosing regimens for OKT-8 in mouse models are not widely documented, as it is not specifically optimized for murine CD8 depletion.

In general, dosing regimens for antibodies like OKT-8 in mouse models can be influenced by factors such as the experimental goal, the specific model setup (including whether it is a humanized model), and the route of administration. For other antibodies targeting CD8 in mouse models, such as clone 2.43, dosing typically ranges from 100 μg to 500 μg per mouse, administered intraperitoneally or intravenously, with dosing schedules often repeated every 3 to 7 days to maintain effective depletion.

For OKT-8, which is used in humanized models, dosing might be more comparable to human dosing strategies, but specific regimens would need to be optimized based on the model's humanization level and the specific experimental conditions. Detailed published studies specifically addressing OKT-8 dosing in mouse models are limited, and dosing would generally need to be empirically determined based on the model's characteristics and the desired outcome of the study.