Immunology Quiz: Lymphoid Organs and Antibodies

Learning Objectives

• Define all terms listed in the Definitions section (page 2).
• Understand the adaptive immune response's key properties.
• Compare and contrast humoral and cell-mediated adaptive immunity, identifying the involved cells.
• Define antigen and antigenic determinant.
• Compare and contrast Class I and Class II MHC/HLA molecule cellular expression and function.
• Describe antigen-presenting cell function and the cell types that act as APCs.
• Define self-tolerance and immunocompetence.
• Define clonal selection.
• Illustrate antibody structure, including heavy and light chains, variable and constant domains, Fab and Fc regions.
• Define antibody affinity and avidity.
• Differentiate between five antibody (immunoglobulin) classes.
• List and describe antibody effector functions.
• Compare and contrast B cell activation in primary and secondary immune responses.
• Describe the role of immunological memory in both responses.
• Differentiate between CD4 helper T cells and CD8 cytotoxic T cells, including their functions.
• Describe the process of CD4 and CD8 T cell antigen recognition.
• Describe T cell activation processes.
• Define costimulation.
• List and describe the functions of TH1, TH2, TH17, and Treg effector CD4 T cells.
• Describe T cell-mediated immunological memory.
• Outline the timecourse of the immune response to an infection.
• Define inflammation.
• Explain immune system interactions with infection timecourses.
• Describe the location and functions of Interleukin-2, CD3, CD28, CD20, CD40, PD-1, glucocorticoid, Interleukin-17, CTLA4.

Definitions (Page 2)

• Immunity: The ability to resist damage from foreign substances (microorganisms, chemicals, or cancer cells).
• Innate immunity: A nonspecific immune system branch responding similarly to each exposure to foreign substances.
• Adaptive immunity: A specific immune system branch, responding faster and stronger each time it encounters a foreign substance.
• Specificity: The ability of adaptive immunity to target a specific substance.
• Diversity: The large number of lymphocytes exhibiting different antigen-specificities.
• Memory: The ability of adaptive immunity to remember previous encounters with a particular substance and respond more effectively.
• Antigens: Substances stimulating adaptive immunity (foreign or self-antigens).
• Foreign antigens: Substances not produced by the body. Examples include pollen, animal dander, food components, and microorganisms.
• Self-antigens: Molecules produced by the body potentially stimulating either beneficial or harmful responses (including tumor and autoimmune responses).
• Antibodies: Proteins produced by plasma cells (differentiated B cells) in response to antigens, also known as immunoglobulins.
• Opsonization: Rendering pathogens susceptible to phagocytosis via antibody or complement protein binding.
• Complement: A group of ~20 proteins (~10% plasma globulin) mediating cell lysis, opsonization, and immune cell recruitment.
• Major Histocompatibility Complex (MHC) molecules: Glycoproteins found on most body cells, displaying processed antigens for immune cell recognition.
• Costimulator: A molecule on antigen-presenting cells, providing a second signal for naive T cell activation.
• Lymphocytes: White blood cells derived from myeloid/lymphoid lineages. (Neutrophils, eosinophils, basophils, monocytes, erythrocytes, platelets).

Cells, Tissues, and Organs of the Immune System

• Hematopoietic stem cells give rise to all blood cells, differentiating into myeloid and lymphoid lineages.
• Myeloid lineage forms neutrophils, eosinophils, basophils, monocytes, erythrocytes, and platelets.
• Lymphoid lineage forms T and B lymphocytes and natural killer (NK) cells.
• Thymus gland releases hormones like thymosin, promoting T cell maturation.
• Lymphoid stem cells migrate to thymus for differentiation
• Spleen filters blood, removing aged erythrocytes and pathogens.
• White pulp contains B and T cells, initiating an immune response.
• Red pulp contains macrophages, clearing cellular debris.

Cells of Adaptive Immunity

• Phagocytic cells (monocytes/macrophages): Engulf and destroy pathogens, using phagocytosis to digest ingested material within the cell's lysosomes.
• Dendritic cells: Bridge between innate and adaptive immunity, acting as antigen-presenting cells (APCs) to activate T and B cells by displaying processed antigens on their surfaces to initiate an adaptive immune response.
• Lymphocytes (B and T cells): Respond specifically to antigens, initiating an adaptive immune response.