The Power of T Cell Clonal Expansion

Published on Oct 30, 2023 By Jason Ellis, PhD Share

Clonal expansion is the process of rapid cell division resulting in the multiplication of genetically identical cell clones from a single parent cell. This exponential growth provides a robust concentration of specific genetic material that aids immune and developmental processes.

Clonal expansion replaces damaged or worn tissues and old cells with new ones, healing wounds and aiding growth. In very early embryonic stages, cell expansion provides a rapid supply of cells to create fully functioning organs and tissues. The body will utilize multiple mechanisms to regulate clonal expansion to ensure controlled cell expansion and proliferation.

Transcription checkpoints exist throughout the cell cycle, which activates division suppressor genes to prevent uncontrolled clonal expansion, thereby averting potential health complications.

T Cell Clonal Expansion and the Human Immune Response

Clonal expansion is critical to launching a strong immune and inflammatory response. When the immune system detects a pathogen, clonal expansion enables the replication of immune cells specifically targeting the invading pathogen. These immune cells, such as T cells, undergo clonal expansion to proliferate rapidly and mount a specific immune defense against the infection. These cloned T cells are called effector cells and carry out the immune response by neutralizing or killing infected cells and recruiting other immune cells to join the attack.

The Basics of T Cells

T cells are critical players in the human immune system, especially in pathogen recognition and specified immune responses. Different types of T cells play fundamental roles in mounting an effective immune defense:

• CD4+ helper T cells release cytokines that help other immune cells by regulating the immune response and directing B cell antibody class switching to increase the number of antigen-specific antibodies responding to the invader.
• CD8+ cytotoxic T cells directly kill infected or abnormal host cells by releasing cytotoxic molecules, such as perforin or granzymes.
• Treg or regulating T cells suppress the immune response when the threat has been eliminated, protecting the body from excess inflammation. Treg also protects against inappropriate responses to self-antigens that could lead to autoimmune diseases.

Clonal Selection: Initiating the Immune Response

T cells all carry a unique surface protein called the T cell receptor (TCR) that triggers T cell activation once bound to its specific antigen. These antigens come in the form of fragments of the invading pathogen that have been digested by an antigen-presenting cell (APC), such as a macrophage, and presented to the T cell.

Clonal expansion starts when a T cell encounters an APC presenting its specific antigen. The resulting cloned T cells share the ability of the parent cell to recognize the antigen.

Control and Regulation of T Cell Clonal Expansion

Excess inflammation as a result of an ongoing immune response can cause great damage to the tissues and organs of the body. After the infection is cleared, most of the active effector T cells undergo apoptosis, resolving the immune response and slowing inflammation. Memory T cells will persist in the bloodstream or tissue to initiate a swift response in the case of reinfection.

The Purpose of T Cell Clonal Expansion

T cell clonal expansion allows the body to mount a precise and vigorous immune response against a foreign antigen to protect the body from infection and build immunologic memory. T cell clonal expansion enables a versatile and specific immune defense. Only T cells with TCRs specific to the encountered antigen or antigens will be activated for clonal expansion, ensuring a targeted immune response.

Due to the diversity in T cells and their unique TCRs, the body is capable of recognizing a wide range of pathogens. Additionally, T cell clonal expansion paired with the creation of memory T cells plays a significant role in the maintenance of adaptive immunity and immune memory. The process of T cell clonal expansion enables the immune system to effectively combat infection, clear pathogens, and establish immunological memory.

Isolating T cells With Microbubbles

Accessing a high yield of activated T cells in a laboratory setting can be difficult without the right tools. Akadeum’s T cell activation and expansion kits are specifically designed with microbubble technology to gently sift through cells and select cells of interest.

Antibodies targeted at T cell surface markers paired with Akadeum’s microbubble technology seamlessly remove T cells from a mixed cell sample, yielding highly viable cells ready for downstream use. Akadeum also offers a line of T cell isolation kits that utilize negative selection to leave cell populations untouched and in optimal condition for study.