NOTES Flashcards
What is the study of a host’s reactions when foreign substances are introduced into the body called?
Immunology
Define immunity.
The state of being resistant to infection
What does immunity involve?
Physiological mechanisms that allow recognition of foreign materials and neutralization, elimination, or metabolism of them
What are the two main types of immunity?
- Adaptive/Acquired Immunity
- Natural/Inate Immunity
List the characteristics of Adaptive/Acquired Immunity.
- Reinforcement
- Inducibility
- Specificity
- Diversity
- Memory
- Specialization
- Self-limitation
- Discrimination
What type of immunity is present since birth?
Natural/Inate Immunity
What is the difference between active and passive immunity?
- Active Immunity: Produces own antibody
- Passive Immunity: Receives antibody from another source
What is the primary function of external defense mechanisms in Natural/Innate Immunity?
Prevent penetration of microorganisms
Name three types of barriers involved in external defense mechanisms.
- Physical Barriers
- Mechanical Barriers
- Chemical Barriers
What is phagocytosis?
Engulfment of cells & particulate matter by leukocytes, macrophages, & other cells
What are the two types of phagocytosis?
- Indirect Phagocytosis
- Direct Phagocytosis
What are the major events in inflammation?
- Vasodilation
- Increase in Blood flow
- Increase in Vascular permeability
- Diapedesis & Chemotaxis
- Destruction of Pathogens by Phagocytes
- Tissue repair
What are the two main lineages of cells in the immune system?
- Myeloid Lineage
- Lymphoid Lineage
What type of immunity is characterized by specificity for each individual pathogen?
Acquired/Specific Immunity
What is lymphopoiesis?
Production of Lymphocytes
What is the largest primary lymphoid organ?
Bone Marrow
What organ is responsible for T-cell maturation?
Thymus
What are the parts of the thymus?
- Cortex
- Medulla
- Thymic Stromal Cells
What is the largest secondary lymphoid organ?
Spleen
What are the two types of splenic tissue?
- White Pulp
- Red Pulp
What is the function of lymph nodes?
Filtration & generation of memory B-cell
What are the stages of B-cell differentiation?
- Pro-B Cells
- Pre-B Cells
- Immature B-Cells
- Mature B-Cells
- Activated B-Cells
What is the role of Interleukin-7 (IL-7) in B-cell development?
Necessary for differentiation of common lymphoid precursors against pro-B cells
What is the composition of a B-cell’s surface antibody?
- 2 identical Heavy Chains
- 2 identical Light Chains
What characterizes activated B-cells?
Exhibit CD25 and undergo antigen-dependent activation
Fill in the blank: The body’s ability to resist foreign organisms and toxins is known as _______.
Immunity
True or False: Natural/Innate Immunity has immunologic memory.
False
What are Marginal Zone B-cells responsible for?
They remain in the spleen to respond quickly to blood-borne pathogens.
Where are Follicular B-cells primarily located?
They are found constantly recirculating to secondary lymphoid organs.
What surface marker do activated B-cells exhibit?
CD25.
What triggers the antigen-dependent activation of B-cells?
When Ag cross-links several surface Ab on the B-cells.
What are Plasma Cells primarily responsible for?
Producing antibodies.
Describe the size and characteristics of Plasma Cells.
Size: 10-20 um; Eccentric or oval nucleus; Heavily clumped chromatin; Abundant Endoplasmic Reticulum and clear Golgi zone.
What is the lifespan and proliferative ability of Plasma Cells?
They are non-dividing, have a short lifespan, and die after producing antibodies.
What do Memory Cells do?
They respond to Ag with increased speed and intensity.
What are the surface markers of Pro-Thymocytes?
CD44 and CD25.
What is the role of Interleukin-7 (IL-7) in T-cell development?
It is necessary at the early developmental stage of T-cells.
What is the composition of the T-cell receptor?
Composed of 8 polypeptide chains, including CD-3 with 6 polypeptide chains.
What do Double Negative Thymocytes lack?
CD4 and CD8 antigens.
What occurs during Positive Selection in T-cell development?
Thymocytes unable to respond to self-MHC Ag die without leaving the Thymus.
What happens during Negative Selection of T-cells?
Surviving double positive T-cells that react strongly with self-Ag are deleted.
What markers do Mature T-cells exhibit?
Either CD4 or CD8.
What do T-helper cells recognize?
Ag along with MHC Class II.
What cytokines do Th1 cells produce?
Interferon gamma (IFN-γ) and Tumor Necrosis Factor-Beta (TNF-β).
What is the primary function of T-Cytotoxic Cells?
Recognizing Ag along with MHC Class I.
What role do T-regulatory cells play?
They suppress the immune response to self-antigens.
What is the function of Natural Killer Cells?
They act as anti-cancer and anti-viral cells.
What triggers NK-cell cytotoxicity?
The balance between activating and inhibitory signals.
What are the components released by NK cells to kill infected cells?
Perforins and Granzymes.
What is the purpose of density gradient centrifugation with Ficoll-Hypaque?
To isolate lymphocytes from whole blood.
What is Flow Cytometry used for?
To segregate lymphocytes into subsets using labeled monoclonal antibodies.
What are the surface markers for T-cells?
CD2, CD3, CD4, CD7, and CD8.
What do fluorescent antibodies do in cell identification?
They screen for subpopulations such as B-cells and T-cells.
What is the difference between direct and indirect immunofluorescence?
Direct uses monoclonal antibodies with a fluorescent tag; indirect uses unlabeled Ab combined with a labeled second Ab.
What is the Rosette Technique?
Mixing isolated lymphocytes with sheep RBC to identify T-cells.
What are adjuvants?
Substances administered with an immunogen to increase immune response.
What factors influence the immune response?
Age, dose, route of inoculation, health status of the host, genetics.
What is Major Histocompatibility Complex (MHC)?
A group of closely-linked genes controlling immune cell interactions and responses.
What does MHC restriction involve?
Recognition of foreign antigen in association with Class I or Class II molecules.
What are autoantigens?
Antigens that belong to the host.
What is an immunogen?
A substance capable of eliciting the formation of immunoglobulins or sensitized cells.
What is the difference between epitope and hapten?
Epitope is the antibody determinant, while hapten is a nonimmunogenic material that creates new antigenic determinants when combined with a carrier.
What is the minimum molecular weight for a substance to be classified as an immunogen?
> 10,000 D.
What methods are used for detecting HLA antigens?
Tissue typing, serological approach, cellular approach, and molecular approach.
