T&B Cell Maturation Overview

Immature T cells that have not yet rearranged their TCR genes and lack CD3 expression.

The process by which T cells in the thymus randomly rearrange TCR gene segments to create unique antigen receptors.

The first checkpoint in T cell development where the successful rearrangement of the β or γδ chain is crucial for survival.

A surrogate α chain that pairs with the β chain to test its functionality during T cell development.

The process by which the Ψα-β dimer interacts with thymic cells, ensuring the β chain is functional and preventing further rearrangement, leading to cell proliferation.

Immature T cells that express both CD4 and CD8 coreceptors after successfully rearranging their TCR genes and expressing CD3.

The process by which double positive thymocytes interact with HLA-peptide complexes on thymic epithelial cells, leading to survival if successful.

Thymocytes that fail to interact with HLA-peptide complexes during positive selection are eliminated by apoptosis, due to lack of survival signaling.

A type of immune cell that can kill infected or cancerous cells.

Receptors on CD8 T killer cells that recognize proteins on the surface of infected or cancerous cells, triggering an immune response.

The process by which CD8 T killer cells release cytotoxic granules containing perforin and granzyme to kill target cells.

A protein released by CD8 T killer cells that forms pores in the target cell membrane, allowing granzyme to enter and induce apoptosis.

A protein released by CD8 T killer cells that enters target cells through perforin-formed pores and activates enzymes that trigger cell death.

A protein on the surface of CD8 T killer cells that binds to Fas on target cells, initiating apoptosis.

The release of a large amount of ATP by CD8 T killer cells, which can damage target cells.

A cytokine released by CD8 T killer cells that binds to TNF receptors on target cells, triggering apoptosis.

The process where T cells are eliminated in the thymus if their TCR binds too strongly to self-antigens, preventing autoimmune reactions.

The process where immature B cells are selected and mature into functional B cells in the bone marrow, developing the ability to recognize and respond to specific antigens.

A critical step in T cell development where immature T cells (thymocytes) are exposed to self-antigens presented by dendritic and epithelial cells in the thymus. Those that bind too strongly are eliminated, while those that bind weakly survive.

Mature T cells that exit the thymus have TCRs that can bind to self-MHC molecules presenting self-peptides, but only at low affinity. This ensures they don't attack the body's own tissues.

A critical cytokine involved in the early maturation of B cells. It promotes the proliferation and differentiation of pro-B cells.

A surface glycoprotein expressed on B cells. It functions as an adhesion molecule, interacting with hyaluronic acid.

The process of B cell development starts from a stem cell that expresses receptors for IL-3 and CD19. These cells proliferate and differentiate through various stages, regulated by specific cytokines and adhesion molecules.

The first step in B cell maturation is an early proliferation in response to cytokines, creating a diverse pool of B cells.

A specialized region within the cell membrane that is enriched in certain lipids. It plays a critical role in T cell activation by dynamically changing its composition and bringing key signaling molecules together.

A protein tyrosine kinase that plays a central role in T cell activation. Primarily involved in the phosphorylation of ITAMs on the TCR complex, initiating the signaling cascade.

Immune Receptor Tyrosine-based Activation Motifs. Short amino acid sequences found within the cytoplasmic tails of proteins involved in T cell signal transduction. They serve as crucial phosphorylation sites for Src kinases.

A key signaling molecule involved in T cell activation. It's a protein tyrosine kinase that's recruited to the TCR complex after ITAMs are phosphorylated. It triggers downstream signaling pathways via phosphorylation.

The major intracellular signaling cascade responsible for T cell activation. It's initiated by TCR engagement with antigen and involves a series of events that lead to gene expression and T cell proliferation.

A critical signaling molecule that's activated downstream of ZAP-70. It's involved in the Ca2+ signaling pathway and leads to the activation of transcription factors.

A transcription factor that plays a crucial role in T cell activation. It's activated by the Ca2+ signaling pathway and translocates to the nucleus to regulate gene expression.

A signaling molecule that plays a role in the activation of NF-kB, a key transcription factor involved in T cell activation. It's activated by DAG and can phosphorylate the inhibitor of NF-kB.

The thymus is an organ located in the chest, behind the breastbone. It plays a crucial role in the immune system by producing and maturing T-cells, which are essential for fighting infections and preventing autoimmune diseases.

Inside the thymus, T-cells undergo a rigorous selection process. This process eliminates T-cells that could attack the body's own cells (self-reactive T-cells), ensuring that the immune system targets only foreign invaders.

The thymus is most active during childhood, gradually decreasing in activity as we age. This means that the production of new T-cells declines over time.

DiGeorge Syndrome is a genetic condition where the thymus doesn't develop properly. This results in a deficiency of mature T-cells, leaving the body vulnerable to infections and making it difficult to fight off diseases.

Cortical epithelial cells are specialized cells found in the thymus that are crucial for guiding the development of T-cells. They provide a microenvironment that helps T-cells mature and become functional.

Macrophages and dendritic cells are immune cells found in the thymus that play a role in presenting antigens to T-cells. This helps T-cells recognize and target specific pathogens.

Notch signaling is a critical pathway that guides the development of T-cells from their precursor stage. It instructs the pre-T-cells to migrate to the thymus where they can mature into functional T-cells.

Thymocytes are immature T-cells that are undergoing development in the thymus. These cells are closely associated with epithelial cells, allowing them to receive the necessary signals and instructions for maturation.

A subset of T cells generated during an immune response that are specialized for a faster and more efficient response to the same antigen upon re-exposure.

During an immune response, the number of effector T cells decreases, but remains higher than the initial count. This is because some effector T cells differentiate into memory T cells, which persist in the body to provide long-term immunity.

Memory T cells are typically more abundant than naive T cells. This means there are more memory cells specific to a particular pathogen compared to cells that have never encountered that pathogen.

Memory T cells can migrate to tissues where they are likely to encounter the same antigen, unlike naive T cells which primarily reside in lymphoid organs. This allows for a quicker immune response at the site of infection.

Memory T cells express high levels of anti-apoptotic molecules, like Bcl-2, which helps them survive for longer periods. This allows them to persist in the body and provide long-term immunity.

Memory T cells can be activated by cross-reacting antigens, meaning they can recognize and respond to antigens that are similar to those they have encountered before. This allows for broader immune protection against related pathogens.

If the number of memory T cells drops below a certain threshold, it takes a longer time for them to be activated and mount an effective immune response, similar to the initial response in a naive individual.

During the expansion phase, naive T cells differentiate into effector T cells and memory T cells. Both CD4+ and CD8+ T cells can differentiate into memory cells.