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18 Cards in this Set

  • Front
  • Back
Differences between innate and acquired immunity?
a. Innate
-Physicial and chemical barriers
-Phagocytic cells (neutrophils/macrophages), large granular lymphocytes
-Cells in blood/tissues
-NOT affected by prior exposure
b. Acquired immunity
-last line of defense
-we react to foreign substance (antigen; molecular epitopes are small peptides)
List 3 major characteristics of an immune response (acquired immunity)
i. Specific: response against inciting antigen only
ii. Adaptive: no response until antigen encountered
iii. Memory: after 1st encounter with antigen, organism is immune (later responses occur faster and stronger, specificity maintained)
Describe basic antibody structure
-Large glycoprotein: 2 heavy chains, 2 light chains
-2 antigen-binding domains: include 1 heavy, 1 light chain
-Fc region: 2 heavy chains (binds to cells with Fc receptors, eg: neutrophils, macrophages)
Describe unique functional feature of IgA antibodies and IgE antibodies
a. IgA: prevents invasion of mucosal surfaces
b. IgE: Cause degranulation of mast cells
2 Characteristics of naive lymphocytes
a. Small
b. Immunocompetent

*specificity of cellular response determined by rxn with 1 antigen.
Describe major types of T lymphocytes

*cell-mediated immunity
1. Cytotoxic T cells: kill target directly when receptor bound (imp for virus-infected cells)
2. Helper T cells: secrete cytokines (paracrine mech), recruit/activate other cells
a. Th1: Promote Cytotoxic t cell activation., recruit macrophage ect to generate inflammation (eg. Inflammatory T cell)
b. Th2: promote B cell activation, development of humoral immunity
3. Regulatory T cells (Treg): known as suppressor T cells (Ts), produce cytokines that inhibit immune responses
Define 3 phases of an immune response
I. Cognitive phase
-B cells: receptor is antibody, all on one cell have same specificity
-T cells: receptor is not antibody, but all on one cell have same specificity (recognizes antigen by its binding pattern)
II. Activation phase: effectors produced in lymphoid organs. Clonality.
III. Effector phase: Antibodies and activated Tc and Th1 cells clear antigen. In periphery. Specific antigen recognition.
Define concept of clonality
Expansion by proliferation of clone with single specificity
Compare antigen binding by B cells and T cells
a. T-cells: Antigen-presenting cells (APC; dendritic cells, related to macrophages,family members present in connective tissue of most organs/stratified epithelia-Langerhans cells, migrate to lymphoid tissues via lymphatic drainage) present antigen to naitive T cells
b. B cells: occurs w/o APC, B cell receptor is antibody.
Compare requirements for activation of B and T cells
a. T cells: APC, TH1 cell/cytokines
b. B cells: activated Th2 cell/its cytokines, differentiate into plasma cells.
Two primary/central
Four secondary/peripheral lymphoid organs (antigen response generated)
a. Thymus (naive T cells) and bone marrow (naive B cells)
b. Lymph node, spleen, mucosal lymphoid tissue (adenoid, tonsil, appendix, Peyer's patches)
**objectives specify four organs, more in syllabus
Define/why necessary?
a. Lymphocyte specificity
b. lymphocyte recirculation
a. Lymphocyte reactive to 1 antigen
-Problems: few lymphocytes reactive to given antigen, antigens can enter at many sites.
b. Naive lymphocytes randomly circulate among secondary organs to encounter antigen
-to address problems above
3 components of secondary lymphoid organs necessary to develop immune response (leading to antibody production)
1. High [] APCs
2. Antigen accumulate here
3. Filtration pattern/lymphocyte recirculation (spleen filters blood, lymph nodes filter lymph, material taken across mucosal surfaces)
Compare two regions lymph node cortex (structure/function)
A. Outer cortex: B cells accumulate/activated here.
*Round follicles (some T cells)
*Secondary follicles (pale germinal central). B cell activation here.
B. Deep cortex/Parafollicular area
*APC's activate T cells.
Compare primary location/function in lymph node
a. Macrophage
b. Dendritic cell
a. Medullary cords (filtration of lymph)
b. Parafollicular region of cortex (antigen presentation to naive T cells)
2 ways lymphocytes can enter a lymph node?

How do antigens enter lymph node?
1. Through postcapillary venules in the deep cortex by receptor-mediated movement
2. Via afferent lymphatics from peripheral tissue.

Antigens:
1. Enter via lymph flow through afferents or from dendritic cells that have captured antigens and settle in cortical tissue
Lymph flow pattern lymph node vs. blood flow

*compartments are entirely separate
Lymph flow: afferent lymphatic, subscapular sinus, intermediate sinus (cortex, then medullary cord), medullary sinus, efferent lymphatic (at hilum)

Blood flow: Artery, arterioles, capillaries (in cortex), high endothelial venules, small vein, vein (enter/exit at hilum)
Compare structure
a. Lymph node
b. Mucosal-associated lymphoid tissues (tonsils/Peyer's patches)
a. Stroma: Capsule and trabeculae (type I collagen/fibroblasts), remainder (except blood vessels) laced with reticular fibers (Type III collagen)
Regions: outer cortex, inner medulla
b. Peyer's patch: follicles and non-follicular area, NO medulla.
*efferent, but NO afferent lymphatics
*Uptake:
-M cells (intestinal epi): transport antigens to lymphoid compartments
-Dendritic cells (lamina propria): send extensions to epithlium.