Podcast
Questions and Answers
What is the primary function of neutrophils in the immune system?
What is the primary function of neutrophils in the immune system?
Which type of lymphocyte is primarily responsible for targeted immune responses?
Which type of lymphocyte is primarily responsible for targeted immune responses?
Which type of lymphoid tissue is responsible for the maturation of lymphocytes?
Which type of lymphoid tissue is responsible for the maturation of lymphocytes?
How do CD56 DIM NK cells primarily operate in the immune response?
How do CD56 DIM NK cells primarily operate in the immune response?
Signup and view all the answers
What percentage of total leukocytes do monocytes typically represent in the blood?
What percentage of total leukocytes do monocytes typically represent in the blood?
Signup and view all the answers
What characteristic differentiates primary lymphoid tissue from secondary lymphoid tissue?
What characteristic differentiates primary lymphoid tissue from secondary lymphoid tissue?
Signup and view all the answers
Which of the following statements about immune function in elderly individuals is most accurate?
Which of the following statements about immune function in elderly individuals is most accurate?
Signup and view all the answers
What is the principal mechanism through which eosinophils mediate their immune response?
What is the principal mechanism through which eosinophils mediate their immune response?
Signup and view all the answers
Which type of immunity is primarily established during fetal development?
Which type of immunity is primarily established during fetal development?
Signup and view all the answers
What role do macrophages play once monocytes migrate into tissues?
What role do macrophages play once monocytes migrate into tissues?
Signup and view all the answers
Which type of T cell is primarily responsible for binding to MHC I molecules and what does it secrete?
Which type of T cell is primarily responsible for binding to MHC I molecules and what does it secrete?
Signup and view all the answers
Identify the correct statement regarding the function of dendritic cells in the immune response.
Identify the correct statement regarding the function of dendritic cells in the immune response.
Signup and view all the answers
Which statement about macrophages is INCORRECT?
Which statement about macrophages is INCORRECT?
Signup and view all the answers
What is the role of PAMP in the immune system?
What is the role of PAMP in the immune system?
Signup and view all the answers
Which type of lymphocyte is characterized by a large nucleus compared to the overall cell volume?
Which type of lymphocyte is characterized by a large nucleus compared to the overall cell volume?
Signup and view all the answers
During early fetal development, which immune cell type is essential for establishing the fetal immune system?
During early fetal development, which immune cell type is essential for establishing the fetal immune system?
Signup and view all the answers
How does immunity function differently in the elderly compared to the young?
How does immunity function differently in the elderly compared to the young?
Signup and view all the answers
Which type of immune response are lymphocytes particularly associated with?
Which type of immune response are lymphocytes particularly associated with?
Signup and view all the answers
In terms of adaptation across generations, which immune component is crucial for memory?
In terms of adaptation across generations, which immune component is crucial for memory?
Signup and view all the answers
What important function do macrophages perform as part of their role in the immune system?
What important function do macrophages perform as part of their role in the immune system?
Signup and view all the answers
What is the primary mechanism through which tolerance between the mother and fetus is established?
What is the primary mechanism through which tolerance between the mother and fetus is established?
Signup and view all the answers
At what point in gestation does the maternal IgG concentration equal the fetal IgG concentration?
At what point in gestation does the maternal IgG concentration equal the fetal IgG concentration?
Signup and view all the answers
Which of the following cells show a significant age-related increase in expression of KLRG-1?
Which of the following cells show a significant age-related increase in expression of KLRG-1?
Signup and view all the answers
What is the main reason that babies are born with naive immune cells?
What is the main reason that babies are born with naive immune cells?
Signup and view all the answers
Which of the following bioactive compounds is NOT found in breast milk?
Which of the following bioactive compounds is NOT found in breast milk?
Signup and view all the answers
What is the primary effect of the complement system's development in infants?
What is the primary effect of the complement system's development in infants?
Signup and view all the answers
What type of antigenic challenge is generally absent in the womb, contributing to fetal immune tolerance?
What type of antigenic challenge is generally absent in the womb, contributing to fetal immune tolerance?
Signup and view all the answers
Why is the immune response in elderly individuals often diminished?
Why is the immune response in elderly individuals often diminished?
Signup and view all the answers
Which immune cell type's function is primarily restored by maternal antibodies post birth?
Which immune cell type's function is primarily restored by maternal antibodies post birth?
Signup and view all the answers
What characterizes Tregs found in the placenta?
What characterizes Tregs found in the placenta?
Signup and view all the answers
What is the primary function of immature, self-reactive T cells in the maturation process?
What is the primary function of immature, self-reactive T cells in the maturation process?
Signup and view all the answers
Which part of the lymph node is primarily responsible for the entry of pathogens and dendritic cells?
Which part of the lymph node is primarily responsible for the entry of pathogens and dendritic cells?
Signup and view all the answers
In what situation will a naïve B cell typically leave the lymph node?
In what situation will a naïve B cell typically leave the lymph node?
Signup and view all the answers
What is the significance of high endothelial venules (HEV) in the lymphatic system?
What is the significance of high endothelial venules (HEV) in the lymphatic system?
Signup and view all the answers
What part of the immune response occurs in the germinal center?
What part of the immune response occurs in the germinal center?
Signup and view all the answers
Which lymphatic tissue is associated with the respiratory system?
Which lymphatic tissue is associated with the respiratory system?
Signup and view all the answers
Which of the following statements best describes haematopoiesis in adults?
Which of the following statements best describes haematopoiesis in adults?
Signup and view all the answers
What is the fate of some germinal center B cells as the immune response subsides?
What is the fate of some germinal center B cells as the immune response subsides?
Signup and view all the answers
What role do macrophages play in the lymph nodes?
What role do macrophages play in the lymph nodes?
Signup and view all the answers
Which of the following statements is true regarding the specificity of lymphocytes?
Which of the following statements is true regarding the specificity of lymphocytes?
Signup and view all the answers
Study Notes
Immunity Across Generations
- Immunity in a baby is initially naive and comes from the mother via the placenta.
- Babies are born with intact immunity, but it is suboptimal.
- Phagocytes migrate slower; cytokines are low; NK functions are incomplete; complement system development is slow; low immunoglobulin levels.
- Babies need time and are helped by the mother after birth.
- Immune protection from mother to baby continues even after birth (NAPI) via the placenta and breast milk.
Lymphoid Organs
- Only a small fraction of lymphocytes are in circulation at any time.
- Primary lymphoid tissue is where lymphocytes develop or mature.
- Secondary lymphoid tissue is where mature lymphocytes are stimulated to respond.
- Lymphoid organs include: adenoids, tonsils, right subclavian vein, lymph node, appendix, lymphatics, left subclavian vein, thymus, heart, thoracic duct, spleen, Peyer's patches (small and large intestines), bone marrow.
Blood Leukocytes
- Neutrophils (40-75%): engulf and digest bacteria.
- Lymphocytes (20-50%): targeted immune response.
- Monocytes (2-10%): engulf and digest bacteria, develop into tissue macrophages.
- Eosinophils (1-6%): kill parasitic worms.
- Basophils (<1%): involved in allergic reactions.
- Granulocytes are neutrophils, eosinophils, and basophils.
Neutrophils Maturation & Clinical Significance
- Neutrophils mature from immature precursors to intermediate to fully mature segmented neutrophils.
- Stages include myelocyte, metamyelocyte, band neutrophil, and mature segmented neutrophil.
- Clinical importance: left shift indicates the presence of immature neutrophils in the blood.
- Left shift can be due to inflammation, leukemia, and/or bone marrow damage.
Natural Killer (NK) Cells
- CD56bright NK cells are a minority type, poorly cytotoxic but high cytokine producers.
- CD56dim NK cells are the majority type, efficient in antibody-dependent cell-mediated cytotoxicity (ADCC) of infected cells and have perforin and granzymes.
- FcyR: CD56bright vs. CD56dim NK cells differ in the expression of FcyR (adhesion).
Monocytes/Macrophages
- Monocytes circulate in the blood and are precursors of tissue macrophages.
- Macrophages act as phagocytes, cleaning up dead cells and microorganisms.
- They also produce cytokines that promote inflammation.
- Macrophages are found in the liver (Kupffer cells), bones (osteoclasts), brain (microglia), skin (Langerhans cells), tissues (histiocytes), kidney (mesangial cells), placenta (Hofbauer cells), lungs (alveolar macrophages).
Dendritic Cells
- Dendritic cells are related to macrophages and have a unique star-shaped morphology.
- They carry degraded and intact pathogens from infection sites to lymphoid organs.
- Dendritic cells stimulate adaptive immune responses.
Lymphocytes (Adaptive)
- Lymphocytes and NK cells are derived from the same progenitor cell.
- Lymphocyte types include B cells (with BCR), T cells (with TCR): Th8 (MHC-I binding), Th4 (MHC-II binding), Th1 (TNFα/IL2/InfY), Th2 (IL4,5,10,13), Ts/Treg (regulatory), and γδ T (no MHC binding).
- Histologically, lymphocytes are recognized by their large, centrally located nuclei compared to their overall cell size.
Maturation of T Cells
- T cells mature in the thymus, starting in the bone marrow and then migrating to the thymus gland for maturation.
Maturation of Thymocytes
- Immature thymocytes (CD3-, 4-, 8-) undergo development in the thymus, passing through stages of double negative, double positive, and to single positive (CD4 or CD8) maturation.
- Positive and negative selection processes mediate thymocyte maturation in the cortex and medulla regions of the thymus.
Clonal Selection Theory
- Many types of T and B cells exist before contact with foreign antigens.
- Lymphocytes have antigen-specific receptors on their surfaces.
- Receptors bind to specific antigens and cause cell proliferation (clones of the same specificity).
- Immature, self-reactive cells are prevented from maturing.
The Lymphatic System
- The lymphatic system is a network of vessels collecting plasma proteins, and debris from the tissues.
- Lymph nodes are at junctions of lymphatic vessels.
- Pathogens and dendritic cells arrive via the afferent lymphatic vessels.
- Pathogens are picked up by resident macrophages and stimulate resident lymphocytes.
Anatomy of a Lymph Node
- Lymph nodes weigh 1 gram (or less) and have lymphoid follicles (mostly B cells), a medullary sinus, an artery, a vein, an efferent vessel, and a marginal sinus.
- Lymph nodes contain afferent and efferent lymphatic vessels to allow the flow of lymphatic fluid and pathogens in the lymph.
Circulation of a Naïve B Cell Through Lymph Node
- Naïve B cells enter the lymph node via the blood vessels, particularly the HEVs.
- If no antigen is encountered, the B cell leaves the lymph node via the efferent lymphatic vessel.
B Cells Encountering Antigen (Germinal Proliferation & Plasma Cells)
- B cells encountering antigens enter the germinal centers for clonal expansion and differentiation.
- Some differentiate into antibody-secreting plasma cells and migrate to the medulla to become plasma cells.
- Some differentiate into memory B cells to provide long-term immunity.
- B cells migrate back to the lymph node to encounter antigens
Lymphoid Areas of Note
- GALT (gut-associated lymphoid tissue): Tonsils, adenoids, appendix, Peyer's patches.
- BALT (bronchial-associated lymphoid tissue): Aggregates of tissue on the lining of the respiratory tract.
- MALT (mucosa-associated lymphoid tissue).
Cells of the Immune System
- Hematopoiesis (in adults) takes place in the bone marrow of the skull, ribs, sternum, vertebral column, pelvis, and femurs.
Immunity Foetus
- Foetus are in a sterile environment.
- Treg cells are increased in the foetus; response is dominated by Th2 immunity.
- The mother develops tolerance for the foetus.
- Foetal thymus development follows a specific pathway from the 3rd branchial arch.
Baby & Immunity
- Babies have intact but suboptimal immunity.
- Babies are born with a naïve immune system, requiring exposure to antigens to mount a proper immune response.
Immune Risk Phenotype and Immuno-senescence (the Elderly)
- CD8 T cells are high in the elderly; CD28 is null.
- CD4 T cell counts and diversity are decreased.
- APC function and antigen presentation are decreased.
- CMV seropositivity, expansion in CD8 cells, and decreased cytotoxic NK cell activity are observed.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the intricate details of immunity across generations, including the transfer of immunity from mother to baby through the placenta and breastfeeding. Additionally, learn about lymphoid organs and their roles in the development and activation of lymphocytes. This quiz covers essential concepts in immunology and lymphocyte function.
