7.1.1 Cellular Immune Response Part 2

A protein that acts as a temporary placeholder in the antigen-binding site of MHC class II molecules during their assembly.

The location where naive T cells encounter and are activated by antigen-presenting cells.

Immune cells with specialized receptors capable of capturing microbes and presenting their antigens to T cells.

The expression of co-stimulatory molecules, such as CD80 (B7.1) and CD86 (B7.2), by dendritic cells is essential for T cell activation.

Activated T cells undergo rapid cell division (proliferation) and release signaling molecules called cytokines.

Naive T cells differentiate into effector T cells, which are specialized to combat specific infections, and memory T cells, which provide long-term immunity.

A therapeutic approach that utilizes antibodies or other molecules to block the interaction between CD40 and CD40L, preventing T cell activation and immune responses.

A type of therapy that uses antibodies that bind to CTLA-4, preventing its inhibitory effect on T cell activation. It's used to treat autoimmune diseases like rheumatoid arthritis and prevent graft rejection in organ transplantation.

A cytokine that stimulates the growth, survival, and differentiation of T cells after activation.

Long-lived T cells that persist after an infection and enable a faster and more effective immune response upon re-encountering the same pathogen.

The weakening or decline of the immune response over time, potentially due to factors such as aging or chronic stress.

Memory T cells rapidly respond to re-infection due to their pre-activation and long-term persistence.

A crucial interaction between CD40 on antigen-presenting cells (APCs) and CD40L on T cells, leading to enhanced T cell activation and immune response

TH1 polarization occurs when the T cell differentiation pathway is guided towards a specific type of helper T cell, particularly effective against intracellular pathogens like viruses and bacteria.

A specific type of helper T cell differentiation that enhances mast cell degranulation and plays a crucial role in allergic responses and parasitic infections.

The process of differentiating T cells into TH17 cells, which primarily activate neutrophils to fight bacterial and fungal infections.

Therapeutic strategies involve targeting the TH1 polarization pathway to fight certain types of cancer, particularly fibrosarcoma.

Cytokines that mediate the differentiation of helper T cells towards the TH2 pathway, including IL-4, IL-5, IL-10, and IL-13.

A co-stimulatory molecule expressed on T cells that binds to B7 molecules on APCs, enhancing T cell activation and promoting survival and proliferation of naive T cells.

A state of unresponsiveness or tolerance in T cells that occurs if they receive the MHC-TCR signal without the second signal (co-stimulation).

A two-step process required for full T cell activation:1. MHC-TCR interaction (recognition of antigen-MHC complex). 2. Co-stimulation (signaling from co-receptor molecules).

CD4+ T cells, also known as helper T cells, play a crucial role in orchestrating the immune response by interacting and coordinating with macrophages, B cells, and dendritic cells.

Molecules that enhance or inhibit the action of T cells by providing additional signals or checkpoints during activation and immune responses.

A co-stimulatory molecule that binds to CD28 on naive T cells, promoting survival and proliferation.

Critical for the helper T cell-dependent antibody response. Interaction promotes the formation of germinal centers and differentiation of B cells into antibody-producing plasma cells.

A co-stimulatory molecule that inhibits T cell activation during the initial stages of antigen presentation in secondary lymphoid organs.

A co-stimulatory molecule that inhibits the activation of effector T cells in peripheral tissues, preventing excessive inflammation and autoimmunity.

A co-stimulatory pathway that enhances the response of T cells by activating antigen-presenting cells (APCs), even without a direct interaction between B7 and CD28.

The process by which cells break down and process antigens from within their cytoplasm. Primarily involving proteins.

Enzymes called proteases break down large antigen proteins into smaller peptide fragments suitable for binding to MHC molecules.

Specialized immune cells, such as dendritic cells (DCs), can engulf and process antigens from outside the cell through a process called phagocytosis.

Exogenous antigens, after being broken down within endosomes (vesicles inside the cell), are processed and prepared for MHC class II presentation.

MHC class I-peptide complexes are displayed on the cell surface, allowing cytotoxic CD8+ T cells to recognize and eliminate infected or cancerous cells.

A cell can express around one million MHC-peptide complexes on its surface, enabling diverse immune responses.

A protein that acts as a temporary placeholder in the antigen-binding site of MHC class II molecules during their assembly.

Mature dendritic cells migrate from tissues to lymph nodes and the spleen, where they present processed antigens to naive T cells.

Lack of co-stimulation during T cell activation can lead to a state of tolerance or unresponsiveness, preventing an immune response.

MHC-TCR interaction and co-stimulation are necessary for full activation of T cells and launching an effective immune response.

Effector T cells, once activated, secrete cytokines that regulate and coordinate the immune response against specific pathogens.

The alpha1 and beta1 domains of MHC class II molecules form the antigen-binding site, where processed peptides bind for presentation to CD4+ T cells.

CD8+ T cells are cytotoxic and play a direct role in killing infected or cancerous cells by releasing cytotoxic molecules.

Cytokine signaling can occur in different ways: Endocrine (long-distance), Paracrine (nearby cells), Autocrine (self-signaling). Their receptors are highly specific.

A phenomenon where one cytokine interferes with or inhibits the effects of another cytokine.

The alpha chain of the TH2 molecule undergoes VJ recombination and assembles before the beta chain undergoes VDJ recombination and it's assembled.

The alpha chain of the TH2 molecule undergoes VJ recombination while the beta chain undergoes VDJ recombination.

Co-stimulatory molecules enhance the response of T cells by activating antigen-presenting cells (APCs), making them more efficient in presenting antigens to T cells.

TH2 cells are primarily involved in activating eosinophils, which are white blood cells that play a role in fighting parasitic infections and allergic reactions.

Interleukin-4 (IL-4) is a key cytokine that promotes eosinophil activation in response to parasitic infections.

TH1 cells are a key part of cellular immunity, helping to control intracellular infections by activating macrophages and cytotoxic T cells.

IL-12 and IFN-y are cytokines that play a crucial role in activating the TH1 differentiation pathway, leading to the production of TH1 cells.