Immunopathology I (Intro) Flashcards
- What are B lymphocytes responsible for❓
2. How do they mediate their effects❓
1.Humoral immunity
2.
Antibodies
Complement system
Cytokines
Killer cells
What is a hypersensitivity rxn❓
Here, an organism responds to a renewed contact with an antigen that it already knows and to which it is hypersensitive
Describe the 4 hypersensitivity rxns and their effectors using the Gell and Coombs classification
Type I
Description: Immediate rxn
Effector: IgE antibodies
Type II
Description: Cytotoxic rxn
Effector: IgG and IgM antibodies
Type III
Description: Immune complexes
Effector: IgG and IgM antibodies
Type IV
Description: Delayed rxn (48hrs)
Effector: T cells
- What happens in immunodeficiency states❓
- Will B-cell defects generally result in a reduced resistance to bacteria or fungal infections❓
- Will T-cell defects generally result in a reduced resistance to bacteria or fungal infections❓
- Deficient immune response to antigen stimuli
- Bacterial infections
- Fungal and viral infections
Gammopathy is due to a neoplastic proliferation of a plasma cell clone
True or false
True
- What is innate immunity❓
2. What are the cells associated with innate immunity❓
- Initial response to eliminate microbes and prevent infections
2. Phagocytic cells (neutrophils, monocytes, macrophages)
Cells w inflammatory mediators
NK cells
Mucosal epithelial cells
Endothelial cells
- What are some examples of innate immunity❓
- Which receptors do they express❓
- What are the best defined pattern recognition receptors❓
1. Anatomical barriers Mechanical removal (cilia) Bacterial antagonism (normal flora) Pattern recognition receptors Antigen nonspecific defense chemicals Complement pathways Phagocytosis Inflammation Fever
- Pattern recognition receptors
Receptors that express PAMPS - Toll-like receptors
What are some differences between innate and adaptive immunity❓
II: Present before infection, not mounted in response
AI: Mounted in response to infection
II: Doesn’t improve with repeated exposure to infection
AI: Improve w repeated exposure
II: Doesn’t recognize every possible antigen
AI: More sensitive and specific
II: Not as powerful
AI: Relatively more powerful
II: Complement system is activated by binding to microbes using the alternative and lectin pathways
AI: Complement system is activated by binding to antibodies using the classical pathway
PAMPS, pathogen-associated molecular patterns/MAMPS, microbes associated molecular patterns are components of innate immunity.
They include❓
LPS on gram negative cell wall
Peptidoglycan and lipotechoic acids on gram positive cell wall
Sugar mannose (microbial glycolipids)
Bacterial/Viral unmethylated CpG DNA motifs
Bacterial flagellin
N-formylmethioine (aa on bacterial protein)
dd and ss DNA from viruses
Glucans from fungal cell walls
Danger associated molecular patterns (unique molecules displayed on injured human cells)
What are the cells associated with humoral immunity❓
T lymphocytes B lymphocytes Macrophages Antigen presenting cells eg dendritic cells NK cells
- How is the alternative pathway of the complement system activated in innate immunity❓
- How is the lectin pathway of the complement system activated in innate immunity❓
- How is the classical pathway of the complement system activated in adaptive immunity❓
- Spontaneously triggered by microbial surface molecules in the absence of antibodies
- Binding of plasma mannose binding lectin to carbohydrates on microbes
- Binding of C1 to antibody (IgM or IgG) bound to antigen
T lymphocytes:
- Account for _____ of circulating lymphocytes
- Are CD3 +ve. True or false❓
60-70%
True
Where are T-cells found❓
How do they recognize antigens❓
What is the end result of T cell activation❓
- •Paracortical areas of lymph nodes
•Periarteriolar sheaths of spleen
•Blood - Antigen specific T-cell receptors
- Differentiation into:
•T8 cells (cytotoxic/suppressor cells)
OR
•T4 cells (T-helper cells)
Describe the T-cell receptor
•Disulfide-linked heterodimer of 2 ppc
•Polypeptide chains may be:
alpha-beta (95%)
OR
gamma-delta
Which antigens do the:
- alpha-beta ppc of TCR recognize❓
- gamma-delta ppc of TCR recognize❓
- Antigens presented by MHC molecules on the surface of APCs
- Doesn’t require APC to bind to antigens
*aggregate at epithelial surfaces for immune surveillance
CD4 and CD8 are function associated molecules.
- Do CD4 molecules bind to Class I MHC molecules or Class II MHC molecules❓
- Do CD4 molecules bind to Class I MHC molecules or Class II MHC molecules❓
- CD4 molecules bind to Class II MHC molecules
2. CD8 molecules bind to Class I MHC molecules
What generates T-cell diversity❓
What generates B-cell diversity❓
- TCR gene rearrangements
2. Somatic rearrangements of immunoglobulin genes
CD4 cells:
- Are activated by❓
- Different into❓
- Function to❓
1.
APC
IL-1
- Helper T cells
Memory T cells
3. •Secrete cytokines •Influence the function of : T and B cells Macrophages NK cells
What are the types of T-helper cells and what functions do they subserve❓
1.
T-Helper 1 cells:
•secrete IL-2 and IFN-gamma
•Involved in:
Delayed hypersensitivity
Macrophage activation
Synthesis of opsonizing and complement-fixing antibodies
- T-Helper 2 cells:
•secrete IL-4, IL-5 and IL-13
- Activation of eosinophils (IL-5)
- Synthesis of IgE (IL-4 and IL-13)
CD8 cells:
- Different into❓
- Are activated by❓
- Function to❓
- Cytotoxic T cells
Suppressor T cells - Cytotoxic c: by contact with APCs/body cells activated w virus
Suppressor c: by contact with antigen and IL-2
- Cytotoxic c: disrupt cell membranes of infected cells and lyse them
Suppressor c: terminate actions of cytotoxic cells
B lymphocytes account for 10-20% of circulating lymphocytes
True or false
True
Where are B-cells found❓
How do they recognize antigens❓
What is the end result of B cell activation❓
- Lymphoid follicles
- B cell zones of peripheral lymphoid organs ie superficial cortex of lymph nodes, white pulp of spleen, tonsils
- Differentiation into plasma cells/antibody-secreting cells
Each B-cell receptor has a unique antigen specificity
True or false
True
Natural killer cells…
- Constitute ____ of circulating lymphocytes
- Are CD3 negative. True or false
10-15%
True
NK cells:
- Express receptors for❓
- Function to❓
- Fc of IgG (CD16)
*they express inhibiting receptors for MHC-1 (lysis with viral or neoplastic transformation) - Lyse IgG coated cells
Kill infected cells
Kill tumor cells
What are APCs, Antigen Presenting Cells❓
Give examples of APCs
- APCs take up antigens, process it and present it to the T cells
- Dendritic cells
Macrophages
Major Histocompatibilty Molecules
Major Histocompatibilty Molecules are critical to T cell immunity
- True or false❓
- Why❓
- On which chromosome is it coded for❓
- True
- T cells recognize only membrane-bound antigens
- Short arm of chromosome 6 (4 MCH/HLA loci)
What are the functions of MHC I, II and III❓
MHC I:
•on all nucleated cells and platelets
- heterodimer
- one polymorphic alpha-chain
- one non polymorphic beta-chain
- encoded by HLA A, B and C
- viral infection is recognized by CD8 and NK cells
- associated w altered HLA Class I expression on the cell surface
MHC II:
•heterodimer
•polymorphic alpha and beta chains
•coded for on HLA DP, DQ and DR
•APCs for CD4 helper cells
MHC III:
•encode components of complement system
Why are individuals able to mount vigorous immune responses against various anigens❓
B/c HLA genes are highly polymorphic and different antigens bind to Class I and Class II gene products
*identical twins have similar HLA genes
What are some examples of diseases associated with HLA alleles❓
Ankylosing spondylitis:
HLA B21, 27 hydrolase deficiency
Hereditary chromatosis:
HLA A deficiency
Autoimmune endocrinopathy:
DR locus
What is..
- An antigen❓
- A complete antigen❓
- An incomplete antigen/hapten❓
- •Foreign substance
•Induces immune response - •Induces immune response
•can specifically react w product of response ie antibody - •⬇️MW substance that acts as an antigen when it binds to a macromolecule
The immune system has about 1*1012 lymphocytes that weigh about 1kg
True or false
True
What are the central immune organs you know❓
What are the peripheral immune organs you know❓
1.
Thymus (T lymphocytes)
Bone marrow (B lymphocytes)
2. Lymph nodes Spleen MALT SALT
Briefly describe the development of the thymus as regards immunity
Epithelial organ till 2nd embryonic month
⬇️
Immature lymph cells migrate from haemopoietic tissue to the thymus
⬇️
Programmed to distinguish btwn “self“ and “non-self”
⬇️
Enter the bloodstream as T lymphocytes
⬇️
Settle in peripheral lymphatic organs
Where are…
- T lymphocytes found in the lymph nodes❓
- B lymphocytes found in the lymph nodes❓
- Paracortical regions (tertiary follicles)
2. Follicular cortical regions
Sinus of node
primary and secondary follicles
Where are
- T lymphocytes found in the spleen❓
- B lymphocytes found in the spleen❓
- Branches of trabecular artery
Periarterial lymph sheaths of arteries of splenic pulp - Splenic arteries
Part of red pulp
Which structures make up the MALT, Mucosa Associated lymphoid tissue❓
Lymphatic pharyngeal ring
GALT, Gut-associated lymphatic tissue
BALT, Bronchial-associated Lymphoid tissue
What makes up the Lymphatic pharyngeal ring❓
Pharyngeal tonsils
Lingual tonsils
Palatine tonsils
What makes up the GALT, Gut-associated lymphatic tissue❓
Peyer’s patches (duodenum)
Follicles of appendix
Solitary follicles of colon
Immunocompetent cells of intestinal mucosa
What makes up the BALT, Bronchial-associated Lymphoid tissue❓
Lymphoid tissue in peribronchial facial sheath
Exocrine Glands (salivary and pancreas)
What is the mechanism by which the MALT gets rid of unwanted antigens❓
M cells on follicle-associated epithelium pass antigens from intestinal lumen➡️intraepithelial lymphocytes
⬇️
Absorbed antigen is received by dendritic cells/macrophages
⬇️
Activation of T / B cells in the adjacent lymph follicle
⬇️
Migrate to peripheral blood
⬇️
Search for antigens and bind
⬇️
Produce IgA immunoglobulin
⬇️
Enters secretions and passed from mother to child
