Vishy -Intro to Host defenses Flashcards
What are the two main functions of the immune system
- Distinguish self from non self
2. Protect the body from invading infectious organisms (parasites, bacteria, fungi, and virus)
The important components of the immune system include:
- innate immunity
2. adaptive immunity
What are characteristics of innate immunity
- Preformed (already in our body)
- Not specific (can kill a wide range of organisms)
- Lacks immunological memory
- Innate immunity does not improve over time
- Often unsuccessful in controlling the infection and hence adaptive immunity kicks in.
what are components of innate immunity
- barriers like skin and mucous membrane
- neutrophils, monocytes, macrophages, dendritic cells and natural killer cells
- antimicrobial peptides and proteins like complement and C-reactive proteins
what are characteristics of adaptive immunity
- the onset is slow
- once active its highly effective
- adaptive immunity is highly specific to a particular organism
- improves over time
- has immunological memory
Natural killer cells are ___ phagocytic
non
what are components of adaptive immunity
- B lymphocytes
2. T lymphocytes
B lymphocytes differentiate in bone marrow and produce ____ or Ig
antibodies; protein molecules that bind to antigens and neutralize the effects of antigens.
T lymphocytes differentiate in thymus and produce ____ or interleukins
cytokines; dont bind to antigens but activate or suppress the cells of innate and adaptive immunity
what are characteristics of neutrophils and what role do they play
- multilobed nuclei
- phagocytose and kill the organisms intracellularly.
- Have a short life
What are characteristics of monocytes and what role do they play
- kidney shaped nuclei
- phagocytose
- leave circulatory system and migrate to diff organs where they differentiate to macrophages
what are macrophages
differentiated forms of monocytes and have a longer life span (months to years)
what are characteristics of dendritic cells and what role do they play in innate immunity
- similar to macrophages
2. long membrane extensions and are capable of both phagocytosis and pinocytosis
Dendritic cells and macrophages can present the antigens to ___ lymphocytes for recognition and initiate ____ immune responses.
T; adaptive
Monocytse present in ____macrophages are present in _____
circulation; tissue
DCs and macrophages express a unique protein antigen on their cell surface called ____
CD14;
_____ are considered to be the most efficient antigen presenting cells
DC’s; capable of ingesting protein antigens and breaking protein antigens into small antigenic peptides and present it to T cells for recognition
What are the diff classes of MHC
Class 1, II, and III
T cells cannot recognize the protein antigens in their ___state, thats why dendritic cells and macrophages within the intracellular compartment internalize the protein antigensand break them down into simple antigenic peptides which then conjugate with ____ molecule and then present on the cell surface for recognition by T cells.
native; MHC
what are MHC class molecules?
self antigens similar to blood group antigens.
T cells can only recognize processed antigenic peptides expressed in conjunction with either MHC class ____ or ____ molecules on the cell surface of dendritic cells.
I, II
Intracellular killing of phagocytosed microbes by monocytes and neutrophils generates:
- reactive oxygen intermediates
- reactive nitrogen intermediates
- generation of antimicrobial peptides
- fusion between phagosome containing microbes with lysosome
what are the antimicrobial peptides
- lactoferrin: sequesters iron; limits the availability of free iron leading to the death of the pathogen due to iron starvation
- defensins: cationic peptides
- Lysozyme