3 - Immunity Overview Flashcards
What is adaptive immunity?
What is innate immunity?
Adaptive immunity: protection results from specific immune components changing or adapting to unique features of the pathogen or agent
Innate immunity: inherent protection against organisms that are permanent from birth
How does passive immunity differ from active immunity?
Passive immunity: receiving preformed antibody for rapid protection. Short duration (T1/2 for Ab = 3weeks) - maternal Ab, IVIg
Active Immunity: Exposure to a foreign antigen for slow protection. Long duration due to memory lymphocytes.
Define immunogen, antigen, and tolerogen?
Immunogen: molecule that induces an immune response
Antigen: molecule that binds to adaptive immune mediators; recognized by a lymphocyte
Tolerogen: molecule that induces immune unresponsiveness to subsequent doses of the molecule
What makes something an immunogen (ie what increases the immunogenicity of something)?
Increased immunogenicity: large, intermediate dose, complex composition, bacteria, effectiev interaction with MHC complex.
Decreased immunogenicity: small size (<2kD), high or low dose, simple composition, no or few bacteria, and ineffective interaction with MHC complex.
Describe locations in the body based on the highest immunogenicity to the lowest immunogenicity?
Highest to lowest:
SubQ > Intraperitoneal > IV > Intragastric
What doees the body do when it decides whether something is self or forein/non-self?
Self: tolerogenic immune response against self antigens
Foreign/non-self: mount an innate or adaptive immune response to the antigen or microbe
Describe innate and adaptive types of specificity and memory?
Specificity:
- Innate: PRRs with limited diversity
- Adaptive: antigen receptors such as TCRs (recognize peptides antigens) and BCRs (complexes of proteins, lipids, carbs in native state)
Memory:
- Innate: none
- Adaptive: memory T and B cells (specific)
Describe intracellular vs. extracellular pathogens?
Intracellular: located within a cells cytoplasm of within a cell vacuole
Extracellular: outside cells, either soluble or associated with the external surface of cells
What is the timing of exposure to the foreign substance or microbe?
Primary immune response: response to the initial exposure to the substance - slower
Secondary immune response: more rapid and stronger response to subsequent exposure to substance
What is a live attenuated vaccine? What is the response and what are the pros and cons?
Modified organism to decrease pathogenicity; limited growth after injection
Induces mainly cellular response (T cells)
PROs: strong, life-long immunity
CONs: may revert to virulent form
What is an inactivated vaccine? What is the response and what are the pros and cons?
Pathogen inactivated but retains epitope (antigen) on surface.
Mainly induces a humoral response (B cells)
PROs: stable and safer than live
CONs: weaker immunity, requires booster vaccines
Where in the body are immunologic decisions made?
Generative immune organs: bone marrow and thymus
Peropheral immune organs: lymph nodes and spleen
At the site of infection
What is innate immunity comprised of?
- Phagocytic cells: Macrophages, neutrophils
- Dendritic cells
- Natural killer cells
- PAlternative and Lectin complement pathways
- Always present and responds immediately
What is adaptive immunity comprised of?
T cells: cell mediated immunity
B cells: humoral immunity
Normally silent (must be activited), responds slowly to first exsposure, memory for faster response to subsequent exposure.
Antigen-specific defense
How is the innate immune system activated?
PRRs recognize PAMPs on bacteria, virus, fungal, or parasitic pathogens.
-Exp Toll-like receptors
Activate pro-inflamm or antiviral signaling
No memory
How is the adaptive immune system activated?
- Antigen: molecule binds to antibody or TCR
- Epitope: specific portion of antigen recognized by receptors on lymphocytes
- Antibody (BCR): recognizes epitopes on proteins and lipid antigens
- TCR: recognizes epitopes on peptide fragments complexed with MHC class I or MHC class II
What is a T cell response and what does it respond to? What are the components?
Antigen-specific response to intracellular pathogens. (cytoplasm of vacuole)
-
Cytotoxic = CD8+ - MHC class I restricted
- goal: KILL
-
Helper - CD4+ - MHC class II restricted
- goal: RECRUIT/ACTIVATE
- cytokine secretion
- CD40/CD40L
What is a B cell response and what does it respond to? What are the components?
Antigen-specific response to extracellular pathogens/antigens and immune surveillance
Plasma cells:
- differentiated B cell that secretes soluble antibodies
- Isotypes of antibodies: IgM, IgG, IgA, IgE
What are the phagocytes and granulocytes involved in the innate immune system? What links the innate and adaptive immune systems? What are the cells of the adaptive immune system?
Innate:
- Phagocytes: PMNs, MØ
- Granulocytes: eosinophils, basophils, mast cells
Linking Innate and Adaptive:
- Dendritic cells - APCs in peripheral lymphoid tissues
- NK cells
Adaptive:
- Lymphocytes
What is the value for a normal WBC count?
4.0 - 10.0 ^3 /microL
What are the percentages of WBC types in a CBC with differential?
Neutrophil: 34-71%
Lymphocyte: 19-53%
Monocyte: 5-12%
Eosinophil: 0-7%
Basophil: 0-1%
What is the function of CD4+ T cells? What are the key markers? What about CD8+ T cells?
CD4+ T cells: B cell differentiation and mø activation; markers are CD3+ and CD4+
CD8+ T cells: kill microbe-infected cells, tumor cells; markers CD3+ and CD8+
What is the function of regulatory T cells? What are the key markers? What about gammadelta Tcells?
Regulatory T cells: suppress T cell functions; markers CD3+, CD4+, CD25+
Gammadelta T cells: helper and cytotoxic
What is the function of B cells? What are the key markers? What about NK cells?
B cells: produce Ab; markers FcR, CD19, CD21
NK cells: kill virus-infected cells, damages cells, and tumors; marker FcRgamma
What are the two primary (generative) lymphoid tissues? What is the function of each?
Bone marrow: hematopoietic progenitors, lymphocyte developement
- naive lymphocytes (small)
- mature lymphocytes (larger, more cytoplasm)
Thymus: development and maturation of T lymphocytes
What are the secondary (peripheral) lymphoid tissues?
Lymph nodes
Spleen
Mucosal or skin-associated lymphatic tissues (MALT/SALT): peyer’s patches, tonsils.
