DSA - Intro to Immunology Flashcards
Antigen
Ags
foreign or “non-self” materials in the body (cells, proteins, DNA, etc.) that trigger an immune response after being recognized by immune cell receptors
Epitope
The part of an antigen molecule where the antibody attaches
Antibodies
Name: Abs, immunoglobulins (from globulin family of proteins)
-Proteins that circulate in the body after an infection or immunization
Humoral immunity
- Part of the immune system that concerns macromolecules in the body fluids (humoral system) and the immune role they play
- Includes secreted antibodies and proteins
Koch, Ehrlich and Metchnikoff
Koch – discovered anthrax
Ehrlich — discovered that immune cells can secrete receptors and coined term ANTIBODY
Metchnikoff — Founded idea of Cellular Theory of Immunity; discovered phagocytes
Difference between the primary and secondary immune response
First response — first exposure to an antigen
Secondary response – second exposure, stronger and better response from body due to familiarity
Memory Cells
- Created following a primary immune response and are activated after subsequent exposures to antigens
- Can be Memory B and Memory T cells
- Generated from antigen-stimulated lymphocytes and differentiate
- Serve no function unless stimulated
Immunological memory
- Each antigen exposure creates more memory cells, leading to better immune response
- Reason why vaccines provide long-lasting protection
Immunization (and how to achieve)
When an organism is made immune to a disease/pathogen/antigen
1) Natural immunity
2) Artificial immunity
Natural Immunity
- Develops following exposure to, infection from and recovery from a LIVE pathogen.
- Development time: weeks
Artificial Immunity
- Developed following exposure to a killed or weakened pathogen but there is no infection -Provides long lasting protection
- Prophylactic
Prophylactic
Preventative medicine, in contrast to therapeutic (treatment for current infection)
Active Immunity
Immunity created from exposure to either live (natural) or killed/weakened (artificial) pathogen
Passive Immunity
When an individual is given another person’s Abs (antibodies) for THERAPEUTIC, rather than prophylactic, treatment
KEY: Short-lived protection
Levels of Immune protection
1) Barriers (skin)
2) Innate Immune system
3) Adaptive immune system
Innate immunity
- First line of defense
- Consists of CELLULAR and HUMORAL components
- Present from birth, utilizes preformed effector molecules to recognize microbe structure, activation leads to ACUTE INFLAMMATION to check pathogens while a game plan is established by the body
Cell-Mediated Innate Immunity components
-Occurs in infected cells, mediated by T cells
1) Phagocytes
2) Mast cells, basophils, eosinophils
3) Natural Killer (NK) cells
Phagocytes
- Neutrophils, monocytes, macrophages
- Kill wide variety of pathogens
- Trigger for intracellular kill is phagocytosis or factor secretion for extracellular (Directed by victim cell)
Mast cells, basophils, eosinophils
- Provides defense against multicellular parasites
- Part of allergenic response
Natural Killer Cells
- NK
- Kill infected and malignant cells
- IDs these cells and initiate apoptosis
Humoral Immunity
- Mediated by Anti-bodies
- Soluble molecules involved in innate immune response
- Called “Inflammatory Mediators”
Acute Phase Proteins
Class of proteins (part of humoral) that increase in concentration in response to immunity (i.e. C-reactive protein (CRP))
Opsonization (opsonins)
Targeting pathogens/molecules for destruction by phagocytes — promote phagocytosis
Complement System
- Part of humoral immunity
- Enhances ability of antibodies to clear pathogens and damaged cells
- Act as opsonins
- 20 proteins that control inflammation via:
1) lysing bacteria
2) abstracting phagocytes to rxn site
3) opsonizing bacteria
Process of Immune cell activation
-Transcription, synthesis and secretion of cytokines and chemokines
Cytokines
- Important for initiating an immune response
- Involved in signaling between cells
Chemokines
-Direct immune cell movement around the body
Adaptive Immune System
-An acquired immune response that allows for the specific targeting of foreign antigens by receptors omg the surface of B-Lymphocytes and T-Lymphocytes
B-Cell Receptor
- Receptor on B-lymphocytes (BCR)
- Binding by specific antigen triggers the release of soluble immunoglobulins (antibodies) by plasma cells. Part of the HUMORAL IMMUNE response of adaptive immunity
T-Cell receptor
-Receptor on a T-Lymphocyte (TCR)
-Recognizes epitopes on antigen, triggering activation of the T-lymphocyte
Part of the CELL-MEDIATED IMMUNE RESPONSE
-All TCRs on same cell are identical
Epitope
specific antigen determinant (i.e. part of an antigen that gives away what it is)
Plasma cells
When activated, secrete specific antibodies to combat pathogen
Memory B-Cell
Forms memory of specific antigen so in future exposure, it can be dealt with quickly
Antigen-Presenting Cells
- APCs
- Macrophages, Dendritic cells and B-cells
- Necessary for T-cell activation
- Contain MHC, which presents foreign antigen to T-cells to trigger response
Major Histocompatibility Complex
- MHC
- Present on the surface of APCs, essential for showing TCRs the antigens
Accessory signals
- Delivered by APCs to activated T-Cell
- Via cytokines and cell-cell contact
Clonal Expansion
When B and T cells rapidly produce an army of identical cells that quickly mature, capable of defending against the same specific antigen
-Triggered by cytokines
T-Lymophocytes
- Mediators of cell-mediated immunity
- Mature in the thymus
- T helper cells – help B-lymph produce antibodies
- Cytotoxis T lymphocytes — kill all cells with foreign microbes
B-lymphocytes
Mediators of humoral immunity
- Only cells capable of producing antibodies
- Mature in the bone marrow
Macrophages
Ingest and destroy foreign substances
Dendritic cells
Capture microbes, display them to lymphocytes to initiate immune response
Follicular dendritic cells
Display antigens to B-lymphocytes in humoral responses
Immunological tolerance
Unresponsiveness to the self’s own antigens.
Mast cells
-Important in allergic response but also recruit other leukocytes to destroy microbes
Generative lymphoid organs
Where mature lymphocytes and produced
Peripheral Lymphoid Organs
-Including the circulatory system, the destination for leukocytes
Naive lymphocytes
- Undifferented cells in circulation who’se only job is to identify antigens.
- Alive for a few weeks and then death if antigen is not encountered
Effector lymphocytes
-Mature progeny of naive lymphocytes that have the ability to produce molecules to kill microbes
Lymph Nodes
- Nodule lymphoid tissue aggregates
- Filters lymph using APCs, searching for antigens to attack
Spleen
- Blood enters spleen and flows through sinusoids (channels).
- Antigens are captured and assembled by dendritic cells and macrophages
- Phagocytes destroy the microbes in the blood.
Cutaneous Immune System
Specialized collections of lymphoid tissues and APC’s located in and under the skin epithelia
Mucosal Immune System
Specialized collections of lymphoid tissues and APC’s located in the gastrointestinal and respiratory tracts.
High endothelial venules
specialized post capillary venules through which naive T cells center lymph nodes
Immune system components
1) Fixed elements
2) Mobile Elements
Fixed elements
- component of the immune system
1) Primary — bone marrow, thymus
2) Secondary — spleen, lymph nodes
