Immunopathology Flashcards
(19 cards)
What are the 3 Pathways for activation of the Complement System?
Alternative Pathway
Lectin Pathway
Classical Pathway
Which of the 3 pathways for activation of the complement system are a result of the innate immune response?
Lectin Pathway
Alternative Pathway
These pathways are initiated in response to the presence of microbes
Which of the 3 pathways for activation of the complement system are a result of Adaptive Immunity?
The Classical Pathway
This pathway is initiated in response to the presence of antibodies
What are TLRs?
Toll-Like Receptors
Pattern recognition receptor, detects microbes and cellular debris
Located on the Cell Membrane and Endosomal Vesicles of immune cells
They activate 2 Transcription Factors
- NF-(kappa)B: stimulates synthesis and secretion of cytokines as well as expression of adhesion molecules (both are critical for recruitment and activation of Leukocytes
- Interferon regulatory Factors (IRFs): stimulate production of Antiviral Cytokines (Type-1 Interferons)
What are NLRs?
NOD-like Receptors
Pattern recognition receptor, detects a wide variety of substances including:
- Products of necrotic cells (uric acid and ATP)
- Ion disturbances (loss of K+)
- Some microbial products
Located in the cytoplasm
Activation of NLRs causes formation of Inflammasome
Inflammasome activates Caspase-1
Caspase-1 cleaves inactive form of the cytokine Interleukin-1, into its active form
IL-1 is a mediator of inflammation that recruits leukocytes and induces fever
What are CLRs?
C-Type Lectin Receptors
Expressed on the plasma membranes of Macrophages and Dendritic Cells
Detect FUNGAL glycans and elicit inflammatory reactions of fungi
What are some important products of the complement system?
C3a
C3b
C5a
Membrane Attack Complex (MAC)
What is C3a?
Product of the Complement System
C3a, with C5a, causes inflammation by promoting recruitment and activation of leukocytes
What is C5a?
Product of the complement system
C5a, with C3a, causes inflammation by promoting the recruitment and activation of leukocytes
What is C3b?
C3b is a product of the complement system
C3b is deposited on the surface of microbes
Acts as a recognition particle, marks microbes for recognition by Phagocytes
Promoted phagocytosis of microbes
What is MAC?
Membrane Attack Complex
A complex of Complement System products that when bound together form a pore in the membrane of microbes causing Lysis of the microbe
What is Humoral Immunity?
One type of Adaptive Immunity
Protects against extracellular microbes and their toxins
Involves B-Cells and their ability to produce antibodies
What is Cell-Mediated Immunity?
One type of Adaptive immunity
Protects against intracellular microbes
Involves T-Cells
What is Clonal Selection?
Lymphocytes specific for a large number of antigens exist before exposure to antigen, and when antigen enters, it selectively activates antigen-specific cells
Lymphocytes of the same specificity are said to constitute a clone
All members of one clone express identical antigen receptors, which are different from the receptors in all other clones
How are T and B cells capable of producing such large diversity of antigen receptors?
Somatic Recombination
How does somatic recombination work?
Genes encoding receptors consist of spatially separated segments that cannot be expressed as proteins without Recombination
During Lymphocyte maturation, these gene segments recombine in random sets and variations are introduced at the sites of recombination, forming many different genes that can be transcribed and translated into functional antigen receptors
The enzyme in developing lymphocytes that mediates recombination of these gene segments is the product of RAG-1 and RAG-2 (Recombination Activating Genes)
All cells contain the antigen receptor genes, but only B and T lymphocytes have recombined antigen receptor genes
What are T Helper Cells?
Helper T Lymphocytes stimulate B lymphocytes to make antibodies and activate other leukocytes (e.g., phagocytes) to destroy microbes
CD4+
What are Cytotoxic T Cells?
Cytotoxic T Lymphocytes (CTLs) kill infected cells
CD8+
What are Regulatory T Cells?
Regulatory T Lymphocytes limit immune responses and prevent reactions against self antigens
Responsible for Peripheral Tolerance
