Cellular Immune Response II

This branch of the immune system, often called CMI, involves cells, particularly T lymphocytes (T cells), in targeting and destroying pathogens. It primarily focuses on eliminating intracellular microbes, like viruses and bacteria that reside within host cells.

These immune cells play a vital role in activating other immune players, like macrophages and neutrophils, to engulf and destroy microbes. They release signaling molecules called cytokines, which coordinate the immune response.

These T cells are specialized in killing cells infected with viruses or intracellular bacteria. They recognize and destroy infected cells, preventing further spread of the pathogen

This type of hypersensitivity is a delayed immune reaction, typically taking 24-72 hours to manifest. It is mediated by T cells, not antibodies, and is characterized by a localized inflammatory response.

These T cells are important for generating an immune response to intracellular pathogens like viruses and bacteria. They stimulate the production of antibodies that help phagocytes engulf microbes and release IFN, a molecule that fights intracellular infections.

These T cells play a key role in defense against parasitic worms (helminths). They promote an immune response that specifically targets these parasites.

A type of T cell that acts like the 'peacekeepers' of the immune system. They suppress excessive immune responses, preventing autoimmune reactions and maintaining immune homeostasis.

These are specialized signaling molecules released by T cells that coordinate and amplify the immune response by activating other immune cells and influencing their functions.

Activated CD4+ T cells can differentiate into different subtypes, like Th1 and Th2 cells. This decision is influenced by the type of pathogen detected, the cytokines released by antigen-presenting cells (APCs), and the activation of specific transcription factors.

Th2 cells are crucial in fighting parasitic infections, especially helminths (worms). They stimulate the production of eosinophils, a type of white blood cell that targets parasites.

Macrophages are immune cells that can be activated in two different ways: classical activation (M1) and alternative activation (M2). These activations lead to different responses and are influenced by cytokine exposure.

The balance between Th1 and Th2 cell activation determines the body's response to intracellular infections. Th1 cells activate macrophages to kill intracellular pathogens, while Th2 cells can inhibit this process.

Lepromatous leprosy is a severe form of leprosy caused by uncontrolled Mycobacterium leprae infection, while tuberculoid leprosy is a less severe form where the immune system effectively controls the infection.

CD8+ effector T cells, also known as cytotoxic T lymphocytes (CTLs), kill infected cells by inducing apoptosis. This process involves the release of cytotoxic molecules like granzyme B and the activation of the Fas death receptor pathway.

CD4+ and CD8+ T cells cooperate during immune responses. CD4+ T cells provide signals to activate and support CD8+ T cells in their killing function.

Fas (CD95) is a death receptor on the surface of cells. When activated by its ligand, FasL, it triggers the apoptotic pathway leading to cell death.

CD4+ Helper T cells release cytokines, which activate other immune cells like macrophages to engulf and destroy microbes.

CD8+ Cytotoxic T lymphocytes directly kill infected cells by releasing cytotoxic molecules like granzyme B, which induce apoptosis.

Delayed hypersensitivity is an immune reaction that takes 24-72 hours to develop, mediated by T cells, and characterized by localized inflammation.

Th1 CD4+ Effector T lymphocytes produce IFN, a key component of cell-mediated immunity, and stimulate the production of antibodies that help phagocytes engulf microbes.

Th2 CD4+ Effector T lymphocytes promote the production of eosinophils, a type of white blood cell that targets and destroys parasites.

Tregs suppress excessive immune responses, preventing autoimmune reactions and maintaining immune homeostasis.

T cell cytokines are signaling molecules released by T cells that coordinate and amplify the immune response.

The type of pathogen dictates the type of immune response needed. For example, a bacterial infection requires different immune cells than a viral infection.

Cytokines, chemical messengers released by immune cells, guide the development of specific CD4+ T cell subtypes. Different cytokines activate different pathways within the T cell.

Transcription factors are proteins that control gene expression, ultimately determining the function of a cell. They are activated by specific signals, like cytokines.

Th2 cells are crucial in fighting off parasitic worms (helminths). They stimulate the production of eosinophils, a type of white blood cell that targets parasites.

Classical macrophage activation (M1) is triggered by inflammatory signals and primes macrophages to kill bacteria and viruses. Alternative activation (M2) is triggered by anti-inflammatory signals and promotes tissue repair and healing.