- Cells mediated immunity is a type of immune response in which immune cells play a crucial role in defending the body against pathogens.
- It is also known as cellular immunity or cell-mediated response.
- Cells mediated immunity involves the activation of T cells, which are a type of white blood cells.
- T cells recognize and bind to antigens presented by antigen-presenting cells (APCs).
- There are different types of T cells involved in cellular immunity, including helper T cells (CD4+), cytotoxic T cells (CD8+), and regulatory T cells.
- Helper T cells activate other cells of the immune system such as B cells and macrophages.
- Cytotoxic T cells directly kill infected cells or cancer cells.
- Regulatory T cells control and regulate the immune response to prevent excessive damage to healthy tissues.
- Cells mediated immunity is an important defense mechanism against intracellular pathogens such as viruses and certain bacteria.
- It is also involved in immune surveillance and the destruction of cancer cells.
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- T cells recognize antigens presented by antigen-presenting cells (APCs) through a process called antigen recognition.
- Antigens are usually protein or peptide fragments derived from pathogens or other foreign substances.
- Antigen presentation occurs when APCs display the antigens on their cell surface.
- Major histocompatibility complex (MHC) molecules play a crucial role in antigen presentation.
- T cells have T-cell receptors (TCRs) on their surface that bind to the antigens displayed by APCs.
- The binding of TCRs to antigens is specific and requires the presence of MHC molecules.
- There are two major classes of MHC molecules, MHC class I and MHC class II.
- MHC class I molecules present antigens derived from intracellular pathogens to cytotoxic T cells.
- MHC class II molecules present antigens derived from extracellular pathogens to helper T cells.
- Antigen recognition by T cells is a key step in the activation of cellular immune responses.
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- Once T cells recognize antigens presented by APCs, they undergo activation to initiate immune responses.
- T cell activation requires two signals: antigen recognition and co-stimulation.
- The first signal is provided by the binding of TCRs to antigens presented by APCs.
- The second signal is provided by the interaction between co-stimulatory molecules on T cells and antigen-presenting cells.
- Co-stimulatory molecules such as CD28 on T cells and CD80/CD86 on APCs are involved in this interaction.
- Without co-stimulation, T cells may become tolerant or undergo cell death.
- Upon activation, T cells undergo clonal expansion, leading to the proliferation of antigen-specific T cells.
- Some activated T cells differentiate into effector T cells, which perform specific functions in immune responses.
- Effector T cells can migrate to the site of infection or inflammation to carry out their functions.
- T cell activation is tightly regulated to maintain immune homeostasis and prevent excessive immune responses.
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- Helper T cells (CD4+) play a crucial role in coordinating immune responses.
- They help activate other immune cells, such as B cells and macrophages.
- Helper T cells recognize antigens presented by APCs through their T-cell receptors (TCRs).
- Antigen recognition by helper T cells leads to the release of cytokines.
- Cytokines are small proteins that act as chemical messengers in the immune system.
- Different subsets of helper T cells produce different cytokines, leading to distinct immune responses.
- Th1 cells produce cytokines that enhance cellular immunity and promote the activation of cytotoxic T cells.
- Th2 cells produce cytokines that promote humoral immunity and stimulate the production of antibodies by B cells.
- Th17 cells produce cytokines involved in inflammation and defense against certain extracellular pathogens.
- The activation and differentiation of helper T cells are essential for efficient immune responses
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- Cytotoxic T cells (CD8+) play a crucial role in killing infected cells or cancer cells.
- They recognize antigens presented by MHC class I molecules on the surface of infected or abnormal cells.
- Cytotoxic T cells directly bind to and kill target cells through various mechanisms.
- One mechanism is the release of cytotoxic granules containing proteins, such as perforin and granzymes.
- Perforin creates pores in the target cell’s membrane, allowing granzymes to enter and induce apoptosis.
- Another mechanism is the activation of Fas ligand (FasL) on cytotoxic T cells, which binds to Fas receptors on target cells, leading to apoptosis.
- Cytotoxic T cells can also induce cell death by releasing cytokines such as TNF-alpha and TRAIL.
- The killing of infected or abnormal cells by cytotoxic T cells helps eliminate pathogens and control tumor growth.
- The activation and regulation of cytotoxic T cells are important for effective immune responses.
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- Regulatory T cells (Tregs) play a crucial role in controlling and regulating immune responses.
- They help maintain immune homeostasis and prevent excessive immune activation.
- Regulatory T cells express a protein called Foxp3, which is essential for their function.
- Tregs suppress the activity of effector T cells and other immune cells, such as B cells and dendritic cells.
- This suppression is achieved through various mechanisms, including the secretion of immunosuppressive cytokines like IL-10 and TGF-beta.
- Tregs can also directly interact with other immune cells and inhibit their function.
- The dysfunction or deficiency of regulatory T cells can lead to autoimmune diseases and immune dysregulation.
- Understanding the role of regulatory T cells is important for developing new therapeutic strategies for immune-related disorders.
- The balance between regulatory T cells and effector T cells is critical for maintaining immune tolerance and preventing autoimmune diseases.
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- Cells mediated immunity plays a crucial role in immune surveillance.
- Immune surveillance refers to the continuous monitoring of the body for the presence of pathogens or abnormal cells.
- Cytotoxic T cells and natural killer (NK) cells are primarily involved in immune surveillance.
- Cytotoxic T cells recognize and kill infected or abnormal cells, including cancer cells.
- NK cells, on the other hand, kill target cells without the need for prior antigen recognition.
- They can recognize certain markers on infected or abnormal cells and induce their death.
- Immune surveillance helps prevent the establishment and spread of infections and tumors.
- Defects in immune surveillance mechanisms can lead to increased susceptibility to infections and tumor development.
- Understanding immune surveillance is important for developing strategies to enhance immune responses against pathogens and cancer cells.
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- Memory T cells are a long-lived population of T cells generated during an immune response.
- They provide long-term immunity against specific pathogens.
- Memory T cells are formed during the initial activation and expansion of T cells.
- After the clearance of an infection, most effector T cells undergo apoptosis.
- However, a small proportion of activated T cells differentiate into memory T cells.
- Memory T cells have distinct characteristics that allow them to respond rapidly and efficiently upon re-exposure to the same antigen.
- They can quickly expand and differentiate into effector T cells, leading to a stronger and faster immune response.
- Memory T cells are an essential component of acquired immunity and provide protection against recurrent infections.
- Vaccination strategies exploit the generation of memory T cells to confer immunity to specific pathogens.
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- Cells mediated immunity is a type of immune response that involves the activation of T cells.
- T cells recognize antigens presented by antigen-presenting cells (APCs) through their T-cell receptors (TCRs).
- The binding of TCRs to antigens requires the presence of major histocompatibility complex (MHC) molecules.
- T cell activation requires two signals: antigen recognition and co-stimulation.
- Helper T cells play a crucial role in coordinating immune responses and activate other immune cells.
- Cytotoxic T cells directly kill infected cells or cancer cells.
- Regulatory T cells control and regulate immune responses to prevent excessive immune activation.
- Immune surveillance involves the continuous monitoring and elimination of pathogens and abnormal cells.
- Memory T cells provide long-term immunity and quick response upon re-exposure to specific antigens.
- Understanding cellular immunity is important for developing therapeutic strategies and vaccines against infectious diseases and cancer.
- Antigen recognition is a crucial step in cells mediated immunity.
- T cells bind to antigens presented by antigen-presenting cells (APCs).
- The binding of T-cell receptors (TCRs) to antigens is specific and requires the presence of major histocompatibility complex (MHC) molecules.
- TCRs have a variable region that interacts with the antigen and a constant region that anchors the TCR to the T cell membrane.
- The interaction between TCRs and MHC-antigen complexes is essential for T cell activation.
- Major histocompatibility complex (MHC) molecules play a key role in antigen presentation and T cell activation.
- MHC class I molecules present antigens derived from intracellular pathogens to cytotoxic T cells (CD8+).
- MHC class I molecules are expressed on almost all nucleated cells in the body.
- MHC class II molecules present antigens derived from extracellular pathogens to helper T cells (CD4+).
- MHC class II molecules are primarily expressed on antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells.
- Helper T cells (CD4+) are crucial for coordinating immune responses.
- They recognize antigens presented by MHC class II molecules on APCs.
- Helper T cells release specific cytokines upon activation.
- Cytokines act as chemical messengers and help regulate immune responses.
- Different subsets of helper T cells produce different cytokines, leading to distinct immune responses.
- Th1 cells are a subset of helper T cells that produce cytokines such as IFN-gamma.
- IFN-gamma enhances cellular immunity and promotes the activation of cytotoxic T cells.
- Th1 cells are important in defense against intracellular pathogens such as viruses and certain bacteria.
- Dysregulated Th1 response can lead to autoimmune diseases such as rheumatoid arthritis and multiple sclerosis.
- Th1 cells can also contribute to tissue damage in chronic inflammatory diseases.
- Th2 cells are a subset of helper T cells that produce cytokines such as IL-4 and IL-5.
- IL-4 and IL-5 promote humoral immunity and stimulate the production of antibodies by B cells.
- Th2 cells play a crucial role in defense against extracellular pathogens such as parasites and allergies.
- Dysregulated Th2 response can lead to allergic diseases such as asthma and atopic dermatitis.
- Th2 responses can also contribute to the development of certain types of cancer.
- Th17 cells are a subset of helper T cells that produce cytokines such as IL-17.
- IL-17 is involved in inflammation and defense against certain extracellular pathogens.
- Th17 cells play a role in defense against fungal infections and some bacterial infections.
- Dysregulated Th17 response can lead to autoimmune diseases such as psoriasis and inflammatory bowel diseases.
- Th17 responses can also contribute to tissue damage in chronic inflammatory diseases.
- Cytotoxic T cells (CD8+) are responsible for killing infected cells and cancer cells.
- Cytotoxic T cells recognize antigens presented by MHC class I molecules on the surface of target cells.
- The recognition of antigens leads to the activation and proliferation of cytotoxic T cells.
- Activated cytotoxic T cells release cytotoxic granules containing proteins such as perforin and granzymes.
- These proteins induce target cell death through the formation of pores in the target cell membrane and the induction of apoptosis.
- Regulatory T cells (Tregs) play a crucial role in immune regulation and tolerance.
- Tregs express a transcription factor called Foxp3, which is essential for their function.
- Tregs suppress the activity of other immune cells, including effector T cells and B cells.
- The suppression is achieved through the secretion of immunosuppressive cytokines such as IL-10 and TGF-beta.
- Dysfunction or deficiency of Tregs can lead to autoimmune diseases and immune dysregulation.
- Immune surveillance is the continuous monitoring of the body for the presence of pathogens and abnormal cells.
- Cytotoxic T cells and natural killer (NK) cells are primarily involved in immune surveillance.
- Cytotoxic T cells recognize and kill infected or abnormal cells based on the recognition of MHC-antigen complexes.
- NK cells, on the other hand, recognize certain markers on infected or abnormal cells and induce their death.
- Immune surveillance is crucial for the early detection and elimination of pathogens and cancer cells.
- Memory T cells are a long-lived population of T cells that provide long-term immunity.
- Memory T cells are generated during the initial activation and expansion of T cells in response to an infection or vaccination.
- Memory T cells can quickly respond to re-infection by the same pathogen and mount a stronger and faster immune response.
- Memory T cells can differentiate into effector T cells, leading to the production of cytokines and the killing of infected cells.
- Memory T cells play a crucial role in acquired immunity and are the basis for vaccination strategies.
Slide 21:
- Vaccination is a strategy that utilizes the immune system’s ability to remember previous infections.
- Vaccines contain antigens derived from pathogens that stimulate the immune system to produce a specific immune response.
- Vaccination leads to the development of memory T cells and B cells, providing long-term immunity.
- Examples of vaccines include those against measles, polio, influenza, and hepatitis.
- Vaccination programs have been highly successful in controlling and eradicating diseases worldwide.
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Slide 22:
- Autoimmune diseases occur when the immune system mistakenly recognizes self-antigens as foreign and attacks healthy tissues.
- Examples of autoimmune diseases include rheumatoid arthritis, multiple sclerosis, and lupus.
- In autoimmune diseases, effector T cells and autoantibodies contribute to tissue damage and inflammation.
- The exact causes of autoimmune diseases are not fully understood but may involve genetic and environmental factors.
- Treatment for autoimmune diseases typically involves the suppression of immune responses.
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Slide 23:
- Organ transplantation involves the transfer of organs or tissues from one individual (the donor) to another (the recipient).
- Transplantation is a treatment option for end-stage organ failure or irreparable tissue damage.
- However, the immune system recognizes transplanted organs as foreign and may mount an immune response to reject them.
- Immunosuppressive drugs are used to prevent or minimize organ rejection.
- Cellular immunity plays a crucial role in organ rejection, and the understanding of cells mediated immunity is important for successful transplantation.
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Slide 24:
- Immunodeficiency disorders are conditions characterized by a weakened or absent immune response.
- These disorders can be primary (genetic) or acquired (secondary to other conditions such as infections or medications).
- Primary immunodeficiency disorders are usually inherited and affect various components of the immune system.
- Acquired immunodeficiency disorders include HIV/AIDS, which specifically targets and destroys helper T cells.
- Immunodeficiency disorders increase the susceptibility to infections and other diseases.
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Slide 25:
- Cancer immunotherapy is a type of treatment that harnesses the immune system to recognize and destroy cancer cells.
- Immunotherapies include checkpoint inhibitors, CAR-T cell therapy, and immune checkpoint inhibitors.
- Checkpoint inhibitors block molecules that suppress the immune response, allowing T cells to attack cancer cells.
- CAR-T cell therapy involves modifying a patient’s T cells to express chimeric antigen receptors, enhancing their ability to target and kill cancer cells.
- Cancer immunotherapy has shown promising results in the treatment of certain cancers.
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Slide 26:
- Allergies occur when the immune system overreacts to normally harmless substances (allergens) such as pollen, dust, or certain foods.
- Allergies involve the activation of effector T cells, resulting in the release of allergic mediators such as histamine.
- Symptoms of allergies include itching, sneezing, runny nose, and skin rashes.
- Treatment for allergies may involve avoiding allergens, medications to relieve symptoms, and immunotherapy to desensitize the immune system.
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Slide 27:
Cells Mediated Immunity - Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)
- Antibody-dependent cell-mediated cytotoxicity (ADCC) is a process in which antibodies attach to infected or abnormal cells and stimulate immune cells to kill them.
- ADCC involves the activation of natural killer (NK) cells, which recognize and bind to the Fc region of antibodies.
- The binding of NK cells to antibodies-coated target cells leads to the release of cytotoxic granules, inducing target cell death.
- ADCC is an important mechanism for the elimination of infected cells and cancer cells.
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Slide 28:
- Inflammatory bowel disease (IBD) is a group of chronic inflammatory disorders that primarily affect the gastrointestinal tract.
- The exact cause of IBD is not known but may involve an abnormal immune response to gut microbiota in genetically susceptible individuals.
- T cells, especially Th1 and Th17 cells, are implicated in the pathogenesis of IBD.
- In IBD, an uncontrolled immune response leads to chronic inflammation and damage to the gut lining.
- Treatment for IBD involves medications to control inflammation and manage symptoms.
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Slide 29:
- Chronic inflammation is a persistent inflammatory response that can occur in various diseases, including autoimmune diseases and cardiovascular diseases.
- T cells play a critical role in chronic inflammation, releasing pro-inflammatory cytokines that sustain and amplify the inflammatory response.
- The dysregulation of cells mediated immunity can lead to excessive and prolonged inflammation, causing tissue damage.
- Understanding the involvement of cells mediated immunity in chronic inflammation can help develop targeted therapies for inflammatory diseases.
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Slide 30:
- Ongoing research in cells mediated immunity aims to understand the precise mechanisms of immune responses and immune