Anti-Human CD4 (Clone OKT-4) – Purified in vivo PLATINUM™ Functional Grade

The monoclonal antibody clone OKT-4 is used in in vivo mouse studies primarily to target and deplete human CD4+ T cells in humanized mouse models—mice that express human CD4, often replacing the murine CD4 gene. This specificity means OKT-4 does not bind mouse CD4 but is valuable for functional studies of the human immune system in a mouse setting.

Essential context and supporting details:

• Target: OKT-4 specifically recognizes human CD4—a glycoprotein found on the surface of human helper T cells, dendritic cells, macrophages, and some NK-T cells.
• Use case: Its principal in vivo application is in humanized mice (often referred to as HuCD4/Tg mice), where the murine CD4 gene is replaced with the human version, enabling studies on human T cell biology or therapies targeting human CD4+ T cells.
• Major application: OKT-4 is used for depletion of human CD4+ T cells in vivo. This allows for:
  • Assessing the role of CD4+ T cells in immune responses.
  • Modeling diseases such as HIV.
  • Preclinical evaluation of therapies that affect the human CD4 compartment.
• Functionality: In these models, administration of OKT-4 results in the depletion of human CD4+ T cells from peripheral blood and lymphoid organs, thereby enabling researchers to analyze downstream immunological or pathological effects.
• Additional uses: In vitro and flow cytometry applications (such as identifying or sorting human CD4+ T cells) are also common but distinct from in vivo depletion.

Summary Table:

• OKT-4 does not recognize native murine CD4, so is not suitable for depleting mouse CD4+ T cells in wild-type mice, only those engineered to express human CD4.

According to supplier and research literature, the key role of OKT-4 in in vivo mouse studies is for selective manipulation of human CD4+ T cells in mouse models with a humanized immune system, providing a powerful tool for immunology and translational research.

Commonly used antibodies or proteins alongside OKT-4 (an anti-human CD4 antibody) in the immunology literature include other T cell markers, costimulatory molecules, and leukocyte subset markers. These combinations are typically used for detailed phenotyping of immune cell subsets and functional studies.

Frequently combined antibodies or proteins with OKT-4:

• CD3: General T cell marker; used to identify total T cells when combined with CD4.
• CD8: Cytotoxic T cell marker; for distinguishing CD4+ (helper) from CD8+ (cytotoxic) T cells.
• CD45: Pan-leukocyte marker; often used for gating strategies in flow cytometry.
• CD19 or CD20: B cell markers; to exclude B cells and clearly identify T cell populations.
• CD14: Monocyte marker; useful for monocyte/macrophage identification and exclusion.
• CD25, CD69, CD62L: Activation markers; to study activation status or subsets of CD4+ T cells.
• CD28, CD80, CD86: Costimulatory molecules; used in studies of T cell activation or costimulation.
• MHC Class II (HLA-DR): To study antigen presentation in conjunction with CD4+ T cells, given CD4's role as a coreceptor for MHC class II.
• Isotype controls (e.g., mouse IgG2b ?): To control for non-specific binding in experiments using OKT-4 or related mouse monoclonal antibodies.

Functional protein combinations:

• Recombinant antigens or MHC-peptide complexes: For studies of T cell activation and antigen specificity, often used together with CD4 staining.
• LCK (lymphocyte-specific protein tyrosine kinase): Studied in signaling pathways initiated through the CD4 receptor.

Rationale:OKT-4 specifically binds the CD4 molecule, present on most helper T cells and subsets of monocytes/macrophages, facilitating fine phenotypic and functional characterization of these cells. Other antibodies are selected based on the specific research focus (e.g., co-stimulatory status, exclusion of non-T-cell populations, identification of regulatory T cell subsets).

Notes:

• OKT-4 recognizes a different epitope on CD4 than other clones like RPA-T4, and these can be used in parallel in multi-color flow cytometry panels.
• In protein engineering and detection systems, recombinant antibody fragments (e.g., scFv) engineered from OKT-4 may be used alongside full-length antibodies for various applications, including diagnostics and bispecific antibodies.

In summary, CD3, CD8, CD45, CD19/20, CD14, and activation/costimulatory markers are most commonly used with OKT-4 in experimental immunology to comprehensively profile T cells and other immune subsets.

Key findings from clone OKT-4 (often cited as OKT4 or OKT4+) in scientific literature primarily relate to two distinct contexts: immunology (particularly characterization of T helper cells using the OKT4 monoclonal antibody) and developmental biology (studies of Oct4 gene expression in cloning and pluripotency). If your query refers to the OKT4 monoclonal antibody (commonly used for human CD4 cell studies), the main findings are as follows:

• OKT4 identifies human helper/inducer T cells: The OKT4 monoclonal antibody recognizes the CD4 molecule on the surface of T lymphocytes. This marker is used to define the subset of T helper cells (CD4+ T cells) which play a crucial role in immune response regulation.
• Role in antigen recognition: OKT4+ T cells are involved in the recognition of antigens presented by Ia (MHC class II) molecules. They recognize both allogeneic Ia and the combination of self-Ia plus foreign antigens.
• Distinction from other T cell subsets: OKT4+ (CD4+) cells are distinct from OKT8+ (CD8+) cytotoxic/suppressor T cells, allowing for functional and phenotypic characterization of immune responses.

Key immunological findings from OKT4 citations:

• OKT4+ cells are the primary T cell population responsible for helper activity in mixed lymphocyte reactions and responses to antigens.
• OKT4+ cell depletion impairs helper T cell functions, highlighting their essential role in coordinating B cell antibody production and immune memory.
• The OKT4 antibody binds to the D3 domain of CD4 and, uniquely, does not block HIV binding, making it useful in studies distinguishing CD4 functions from HIV interactions.

If your question refers to Oct4 in developmental biology (sometimes confusingly similar in search results), key findings relate to:

• Oct4 as a marker of pluripotency:
  • Abnormal expression or distribution of Oct4 in cloned embryos is correlated with decreased pluripotency and developmental abnormalities.
  • Clones with normal Oct4 expression, especially when achieved via clone–clone aggregation, show improved development and greater likelihood to contribute to embryonic lineages.
  • Errors in Oct4 reprogramming are a major cause for the low developmental success rates in somatic cell cloning.

If you intended a particular context, specifying "OKT4 antibody clone" (immunology) or "Oct4 gene in clones" (developmental biology/pluripotency) can refine the answer further.

Dosing regimens for OKT-4 (anti-CD4, clone OKT4) vary based on the specific mouse model, disease context, and study aim, and information must often be adapted from studies using analogous anti-CD4 antibodies, as OKT-4 is a well-established anti-human CD4 clone but is less commonly used in mice compared to clones like GK1.5.

Key findings from available sources:

• Species Selectivity: OKT-4 specifically targets human CD4, so it is typically used in human CD4 transgenic (huCD4/Tg) mouse models where human CD4 is expressed.
• Dose Range: Studies in huCD4/Tg mice have reported OKT-4 or analogous antibodies given at 5 to 250 mg/kg per dose, with precise dosing determined by the model, application, and whether short-term or long-term modulation is needed.
• Dosing Schedules:
  • In a Pneumocystis carinii infection model: Weekly intravenous (i.v.) doses of 25 or 250 mg/kg for 6 weeks.
  • In C. albicans infection models: Three daily intraperitoneal (i.p.) doses at 1 or 100 mg/kg/day, or extended to weekly maintenance dosing.
  • In a melanoma metastasis model: Four weekly i.v. doses at 25 or 250 mg/kg starting before tumor challenge.
• Route of Administration: Intravenous (i.v.) and intraperitoneal (i.p.) routes are both used, depending on the desired pharmacokinetics and tissue distribution.

For comparison, in common in-vivo mouse-specific anti-CD4 antibodies (example: GK1.5), the standard dosing for murine CD4 depletion is typically 200–250 µg per mouse, given 2–3 times per week by intraperitoneal injection, mainly in CD4+ T cell depletion studies in standard immunology mouse models. These doses are much lower than humanized antibody or OKT-4 doses because of differences in affinity, isotype, and target abundance.

Summary Table: OKT-4 Dosing in Mouse Models

Critical distinctions:

• OKT-4 is not used in wild-type mice due to species specificity.
• Dose and schedule are adapted to the disease model and desired immune modulation (depletion vs. signaling blockade).
• Safety and efficacy must be validated for each new disease model and study design.

No evidence was found of standardized OKT-4 regimens in non-transgenic mice, and protocol variability is considerable depending on the experimental aims. Where not specified, check the latest literature for your specific mouse model and experimental goal, as optimal regimens may differ.