Immune System Flashcards
What are the two main branches of the immune system?
The immune system comprises innate immunity and adaptive immunity.
Differentiate between innate immunity and adaptive immunity.
Innate immunity is non-specific and immediate, while adaptive immunity is antigen-specific and involves memory.
Which cells are involved in innate immunity that engulf pathogens?
Phagocytes such as neutrophils and macrophages.
What is the primary role of dendritic cells in the immune system?
Dendritic cells capture, process, and present antigens to T cells to initiate adaptive immune responses.
Name the major classes of antibodies and their function.
IgG, IgA, IgM, IgE, IgD.
IgG: Most abundant, crosses placenta, opsonization, neutralization.
IgM: Pentamer, early response, efficient complement activation.
IgA: Secretory, mucosal immunity, prevents pathogen attachment.
IgE: Allergic reactions, parasitic infections, triggers mast cells.
IgD: Receptor on B cells, unclear functional role.
Which antibody class is most abundant in the bloodstream and tissues?
IgG
What is the function of IgA antibodies?
IgA protects mucosal surfaces by neutralizing pathogens and toxins.
Describe the structure of an antibody.
Antibodies have a Y-shaped structure consisting of two heavy chains and two light chains.
What is the role of helper T cells in the immune response?
Helper T cells assist B cells in antibody production and activate cytotoxic T cells.
How do cytotoxic T cells kill their targets?
Cytotoxic T cells induce apoptosis in infected or cancerous cells by releasing perforin and granzymes.
Explain the process of opsonization.
Opsonization involves antibodies binding to pathogens to facilitate phagocytosis by neutrophils and macrophages, or to block the pathogen from binding to/entering another cell.
What is immunosenescence?
Immunosenescence refers to the decline in immune function associated with aging.
How does the thymus contribute to the immune system?
The thymus is where T cells mature and differentiate.
Name two types of lymphoid organs involved in immune responses.
Lymph nodes and spleen.
What is clonal selection in the context of immune responses?
Clonal selection refers to the proliferation of specific B or T cells upon encountering an antigen.
Explain the difference between primary and secondary immune responses.
Primary responses are slower and produce IgM initially, while secondary responses are faster and produce more IgG.
Why are infants susceptible to infections in the first few months of life?
Infants have immature immune systems and rely on maternal antibodies transferred across the placenta.
How do memory cells contribute to long-lasting immunity?
Memory cells facilitate rapid and robust immune responses upon re-exposure to a pathogen.
What is the role of cytokines in immune responses?
Cytokines are signaling molecules that regulate the intensity and duration of immune responses.
Define autoimmunity.
Autoimmunity occurs when the immune system mistakenly attacks the body’s own tissues.
Name a disease caused by autoimmunity affecting the thyroid gland.
Hashimoto’s thyroiditis.
How does inflammation contribute to immune responses?
Inflammation recruits immune cells to sites of infection and promotes tissue repair.
What are the functions of regulatory T cells?
Regulatory T cells suppress immune responses to prevent autoimmune reactions.
Explain the process of antigen processing and presentation.
Antigen-presenting cells digest antigens and display antigenic fragments on their surfaces bound to MHC molecules.
Which cells are responsible for producing antibodies?
Plasma cells derived from activated B cells.
Describe the structure and function of IgE antibodies.
IgE antibodies are involved in allergic reactions by binding to allergens and triggering mast cell degranulation.
What is the role of natural killer cells in the immune system?
Natural killer cells detect and destroy infected or cancerous cells lacking MHC molecules.
How does breastfeeding provide passive immunity to infants?
Breast milk contains antibodies (IgA) that protect against gastrointestinal infections.
Name two examples of primary lymphoid organs.
Thymus and bone marrow.
What is the function of the complement system in immunity?
The complement system enhances phagocytosis, induces inflammation, and lyses pathogens.
What are haptens, and how do they become immunogenic?
Haptens are small molecules that become immunogenic when bound to carrier proteins.
How does the immune system distinguish between self and non-self antigens?
Through recognition of self-markers (like MHC molecules) and detection of foreign antigens that do not match the body’s own molecular patterns.
What role do antibodies play in the prevention of bacterial infections?
Antibodies can neutralize bacterial toxins and promote phagocytosis of bacteria.
Name the primary effector cells of cell-mediated immunity.
Cytotoxic T cells.
Describe the process of antibody-mediated immunity.
Antibodies bind to antigens on pathogens, marking them for destruction by phagocytes or complement proteins.
How does aging affect the adaptive immune system?
Aging is associated with decreased thymic function and reduced diversity of T cell receptors.
What is the role of B cells in adaptive immunity?
B cells produce antibodies and develop into memory cells upon encountering specific antigens.
Explain the concept of immunological memory.
Immunological memory allows for faster and more robust immune responses upon re-exposure to a previously encountered antigen.
How does HIV impair the immune system?
HIV infects and destroys helper T cells, compromising adaptive immune responses.
What is the function of Toll-like receptors in innate immunity?
Toll-like receptors detect pathogen-associated molecular patterns and activate immune responses.
Describe the process of T cell activation.
T cell activation requires recognition of antigen-MHC complexes and co-stimulatory signals from antigen-presenting cells.
How do antibodies contribute to immunity against viral infections?
Antibodies can neutralize viruses, prevent viral entry into cells, and promote viral clearance.
What are the consequences of impaired phagocytic function in innate immunity?
Impaired phagocytic function leads to increased susceptibility to bacterial infections.
What are the functions of complement proteins in innate immunity?
Complement proteins opsonize pathogens, induce inflammation, and lyse microbial cells.
How do allergies involve the immune system?
Allergies result from hypersensitive immune responses to harmless antigens, triggering inflammatory reactions.
Explain the process of antibody diversification in B cells.
Antibody diversification occurs through somatic hypermutation and class switching in activated B cells.
What is the significance of MHC diversity in immune responses?
MHC diversity allows for recognition of a wide range of antigens by T cells, contributing to immune specificity.
Describe the process of antigen processing for MHC class I presentation.
Antigens are degraded in the cytosol, peptides are transported into the endoplasmic reticulum, where they bind to MHC class I molecules and are presented on the cell surface.
Differentiate between the roles of CD4+ and CD8+ T cells in adaptive immunity.
CD4+ T cells (helper T cells) assist in activating other immune cells, while CD8+ T cells (cytotoxic T cells) directly kill infected or cancerous cells.
What is the function of the thymus in T cell development?
The thymus provides a microenvironment for T cell maturation, where T cells undergo positive and negative selection to ensure self-tolerance.
Explain the concept of immunological tolerance.
Immunological tolerance is the state of unresponsiveness to self-antigens, preventing autoimmune reactions.
Describe the role of regulatory T cells (Tregs) in immune regulation.
Tregs suppress excessive immune responses and maintain immune tolerance by inhibiting effector T cells.
How does somatic hypermutation contribute to antibody diversity?
Somatic hypermutation introduces point mutations in antibody genes during B cell activation, resulting in antibodies with enhanced antigen-binding affinity.
Discuss the role of cytokines in coordinating immune responses.
Cytokines regulate immune cell proliferation, differentiation, and communication, shaping the intensity and direction of immune responses.
What are the functions of memory T cells in adaptive immunity?
Memory T cells rapidly respond to re-infection by differentiating into effector T cells, providing enhanced protection against previously encountered pathogens.
Explain the process of class switching in antibody production.
Class switching involves B cells changing the constant region of their antibodies from IgM or IgD to IgG, IgA, or IgE, altering their effector functions.
Describe the structure and function of Toll-like receptors (TLRs) in innate immunity.
TLRs recognize specific pathogen-associated molecular patterns (PAMPs), initiating innate immune responses and cytokine production.
How do effector T cells contribute to immune responses?
Effector T cells (both CD4+ and CD8+) directly combat infections or tumors through cytokine secretion or cell-mediated cytotoxicity.
Discuss the role of B cell co-receptors in antibody production.
B cell co-receptors, such as CD19 and CD21, enhance B cell activation and antibody production upon antigen recognition.
How does the complement system contribute to both innate and adaptive immunity?
Complement proteins opsonize pathogens, induce inflammation, and facilitate immune cell lysis, enhancing both innate and adaptive immune responses.
Discuss the role of antigen-presenting cells (APCs) in initiating adaptive immune responses.
APCs (dendritic cells, macrophages, B cells) capture, process, and present antigens to T cells, activating adaptive immune responses.
How does aging affect the adaptive immune system, specifically T cell function?
Aging is associated with reduced diversity and function of naïve T cells, compromising immune responses to novel antigens.
Discuss the mechanisms of immune evasion employed by pathogens.
Pathogens evade immune responses by antigenic variation, inhibition of antigen presentation, or suppression of immune cell functions.
What is the role of chemokines in immune cell trafficking and inflammation?
Chemokines attract immune cells to sites of infection or inflammation, regulating immune cell trafficking and activation.
How do superantigens differ from conventional antigens in T cell activation?
Superantigens bind outside the peptide-binding groove of MHC molecules, activating large numbers of T cells and causing excessive immune responses.
What is the function of memory B cells in long-term immunity?
Memory B cells persist after initial infection or vaccination, quickly differentiating into plasma cells upon re-exposure to the same antigen.
Discuss the role of memory CD8+ T cells in protective immunity against viral infections.
Memory CD8+ T cells provide rapid and effective responses upon re-exposure to viral antigens, clearing infected cells before viral spread.
How do lipid mediators (e.g., prostaglandins, leukotrienes) regulate immune responses?
Lipid mediators modulate inflammation, vascular permeability, and immune cell activation during innate and adaptive immune responses.
Discuss the concept of immune privilege in specific anatomical sites (e.g., eye, brain).
Immune privilege refers to restricted immune responses in certain tissues to prevent damage
