T Cell Activation and Expansion
T-cell therapy has emerged as a promising immunotherapeutic approach for the treatment of various diseases, including cancer and autoimmune disorders. Large-scale production of human T cells for cellular therapy is a complex, multi-step process that presents many opportunities for optimization to obtain maximum yield while retaining the desired end phenotype and function.
Workflow of T Cell Isolation, Activation, and Expansion
- T cell isolation
The first step in this process is the isolation of T cells from a suitable source, such as peripheral blood, bone marrow, or tumor-infiltrating lymphocytes (TILs). Several techniques can be employed for T-cell isolation, including density gradient centrifugation, magnetic bead separation, and flow cytometry-based sorting. Each method has its benefits and limitations, and the choice depends on factors such as cell yield, purity, and downstream applications. - T cell activation
Once isolated, T cells need to be robustly activated to enhance their cytotoxic potential and effector functions. Activation is typically achieved by stimulating T cells with specific antigens or mitogens. Commonly used techniques for T cell activation include the use of anti-CD3/CD28 antibodies, dendritic cells loaded with antigens, or genetic modification to express chimeric antigen receptors (CAR-T cells). Activation signals received through the T cell receptor (TCR) and co-stimulatory molecules such as CD28 are critical for T cell proliferation and cytokine production. - T cell expansion
The activated T cells are then expanded ex vivo to increase their quantity for therapeutic applications. This involves providing the cells with appropriate growth factors and cytokines in a culture system that mimics the physiological conditions. Commonly used growth factors for T cell expansion include interleukin-2 (IL-2), IL-7, IL-15, and IL-21. Additionally, certain feeder cells, such as antigen-presenting cells or artificial antigen-presenting cells, can be incorporated to provide co-stimulation signals and enhance T-cell expansion.
Optimization of T-cell Expansion Protocols
Several factors need to be optimized to achieve optimal T cell expansion, including culture medium composition, cytokine concentrations, feeder cell types, and culture vessel selection.
- Early cell dilution
Maintaining T cells at lower cell densities during early T cell expansion improves T cell growth and viability. Some study identifies day 3 as a key time point for culture volume adjustment when optimizing T-cell expansion protocols. - Cytokine concentrations
The optimal concentration of cytokines, such as IL-2, IL-7, IL-15, and IL-21, is important for promoting T cell expansion and maintaining their effector functions. Different T cell subsets may have varying requirements for cytokines, and therefore, proper titration of cytokine concentrations is necessary for effective expansion. - Feeder cell types
Feeder cells provide co-stimulatory signals and create a supportive microenvironment for T-cell expansion. Various cell types can serve as feeder cells, including irradiated peripheral blood mononuclear cells, Epstein-Barr virus-transformed B cells and artificial antigen-presenting cells. The choice of feeder cell type should be based on their ability to induce robust T-cell expansion and minimize potential immunological complications.
Creative Bioarray Relevant Recommendations
Creative Bioarray understands the importance of high-quality T-cell products for successful immunotherapies. So, we offer T-cell products, T-cell expansion medium, T-cell activator, and T-cell isolation kits.
