The lymphocyte population consists of T cells, B cells and Natural Killer cells. These cells are often extracted from whole blood or leukopaks using ficoll, a hydrophilic polysaccharide that separates layers of blood, with monocytes and lymphocytes forming a buffy coat under a layer of plasma. T Cells have a key function in the adaptive immune system. They can either promote the growth and differentiation of other immune cells or show suppressive function and down-regulate immune reactions.
CD3 T cells
CD3 is initially expressed in the cytoplasm of pro-thymocytes, the stem cells from which T-cells arise in the thymus. The pro-thymocytes differentiate into common thymocytes, and then into medullary thymocytes, and it is at this latter stage that CD3 antigen begins to migrate to the cell membrane. The antigen is found bound to the membranes of all mature T-cells, and in virtually no other cell type, although it does appear to be present in small amounts in Purkinje cells. This high specificity, combined with the presence of CD3 at all stages of T-cell development, makes it a useful immunohistochemical marker for T-cells in tissue sections. The antigen remains present in almost all T-cell lymphomas and leukaemias, and can therefore be used to distinguish them from superficially similar B-cell and myeloid neoplasms. Because CD3 is required for T-cell activation, drugs (often monoclonal antibodies) that target it are being investigated as immunosuppressant therapies (e.g., otelixizumab) for type 1 diabetes and other autoimmune diseases.
CD3 is expressed on all T cells and CD56+ NKT cells, and is associated with the T cell receptor. 70–80% of human peripheral blood lymphocytes and 65–85% of thymocytes are CD3+.
CD3+ T cells are isolated from normal peripheral blood using negative immunomagnetic selection directed against the CD3 surface antigen. Negative selection is preferred with immune cell isolations to avoid activation of the cells by the antibody.
CD4 T cells
CD4+ T Cells are produced using an indirect magnetic labelling system for the isolation of untouched CD4+ T helper cells from human PBMCs at the Zen-bio facility. Non-CD4+ T cells are screened for CD8, CD14, CD15(16) CD19, CD56, and glycophorin A. CD4+ T lymphocyte cells are isolated from normal peripheral blood using negative immunomagnetic selection directed against the CD4 surface antigen. Negative selection is preferred with immune cell isolations to avoid activation of the cells by the antibody.
CD4+ T lymphocytes play a central role in regulating the cell-mediated immune response to infection. These cells are often known as “helper” T cells, as they act on other cells of the immune system to promote various aspects of the immune response, including immunoglobulin isotype switching and affinity maturation of the antibody response, macrophage activation, and enhanced activity of natural killer (NK) cells and cytotoxic T cells (CTL).
Applications for CD4+T cells include drug testing and drug discovery, assessing immune response, toxicology, genetic studies, inflammation, and autoimmune diseases.
ZenBio’s CD4+ cells are isolated from anticoagulated blood collected in the United States from a volunteer adult donor who has signed an IRB or FDA-validated donor consent form that specifically lists both the intended uses for the donation for non-clinical research and confirms the procedures for processing the samples are Standard Operating Procedure (SOP) managed GLP protocols in compliance with all legal and ethical regulations.
CD8 T cells
CD8+ T cells are recognised as TC cells once they become activated and are generally classified as having a pre-defined cytotoxic role within the immune system. However, CD8+ T cells also have the ability to make some cytokines. Antigen presentation stimulates T cells to become either “cytotoxic” CD8+ cells or “helper” CD4+ cells. A cytotoxic T cell belongs to a sub-group of T lymphocytes that are capable of inducing the death of infected somatic or tumour cells; they kill cells that are infected with viruses (or other pathogens) or are otherwise damaged or dysfunctional. Most cytotoxic T cells express T-cell receptors that can recognise a specific antigenic peptide bound to Class I MHC molecules, present on all nucleated cells, and a glycoprotein called CD8, which is attracted to non-variable portions of the Class I MHC molecule. The affinity between CD8 and the MHC molecule keeps the TC cell and the target cell bound closely together during antigen-specific activation.
CD8+ Cytotoxic T cells are derived from fresh peripheral blood of healthy donors and produced at the ZenBio facility. Peripheral blood CD8+ Cytotoxic T cells are isolated from mononuclear cells using positive immunomagnetic selection for CD8+ cells. Immediately after isolation, the freshly prepared CD8+ Cytotoxic T cells are cryopreserved using a serum-based cryopreservation medium.
About ZenBio
ZenBio was created to meet the needs of investigators interested in understanding human obesity, diabetes, and cardiovascular disease. Since then, they have expanded their product portfolio to include a wide variety of primary cells, blood-derived products and other essential reagents and tools for cell culture research:
- Human cell-based products, including fresh apheresis and bone marrow, isolated haematopoetic cells and human platelet lysate
- ZenComplete™ and ZenSkin™ research solutions platforms for cosmetic and personal care product companies
- Contract research services for outsourcing key projects
- Cell-based assay development and custom consultations
- Individualised screening programs (cell-based or biochemical)
- Cell characterisation and molecular biology services
Caltag Medsystems is the distributor of ZenBio products in the UK & Ireland.