Innate Immunity Flashcards
What type of white blood cells do macrophages develop from and when do they develop into macrophages.
Monocytes. They develop into macrophages when they move from the bloodstream into the tissues. They undergo further differentiation into a variety of histologic forms
What are Polymorphonuclear Leukocytes?
A population of cells that are also referred to as granulocytes. Include basophils, eosinophils, and neutrophils. They are short lived phagocytic cells that include enzyme rich lysosomes.
What are Neutrophils?
PMN Leukocyte. They are the most common white blood cell in the bloodstream, and are among the first immune cells to defend against infection. They must be signaled to leave the bloodstream and enter the tissues, which is usually done by the bacteria themselves. They contain enzymes that help kill and digest pathogens.
What are Eosinophils?
PMN Leukocyte. White blood cells that circulate in the blood stream, but are less against pathogens compared to neutrophils and macrophages. They can ingest foreign cells and release toxic substances or enzymes to kill invaders.
What are Basophils?
PMN Leukocyte. White blood cells that do not ingest foreign invaders. Contain granules full of histamine that is released when in contact with allergens. Histamine increases blood flow to damaged tissues.
What are Natural Killer Cells?
Immune cells that are made to “kill” cells. They recognize and attach to infected cells or cancer cells and release biologically potent substances that damage the membranes of the cells. They also produce cytokines that regulate T cells, B cells, and macrophages.
How can Natural Killer Cells seek and destroy their targets?
Natural killer cells lack antigen- specific receptors. The find their targets through cell to cell contact, which allows them to determine whether a potential target cell has lost a particular self antigen called the majpr histocompatibility complex (MHC) class 1. NK cells have killer- cell inhibitory receptors, which bind to MHC class 1 molecules on normal cells. When they bind, KIRs inhibit the events that would lead to the cell being destroyed. So, if MHC class 1 is not present, the KIR is not inhibited and the cell will be destroyed.
What are Innate Lymphoid Cells?
Immune cells that belong to the lymphoid lineage but do not produce antigen specific receptors. They have been shown to aid in protective immunity at the acute phase of infections, tissue remodeling, anatomical containment of commensals microorganisms, wound healing, and maintaining epithelial integrity of mucosal sites.
What are the cells of the innate immune system derived from?
First, hematopoietic precursor cells and then myeloid cells.
Is innate immunity specific or non specific?
Non specific
What is the first line of defense of the innate immune system?
Physical and chemical barriers
What are some examples of physical and chemical barriers?
- The skin acts as a protective barrier to the outside world.
What does innate immunity mean?
Innate means that it is immunity present at birth and does not have to be learned through the presence of an invader. It thus provides an immediate response to foreign invaders.
What is the complement system?
A part of the immune system them enhances or complements the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organisms, promotes inflammation, and attacks pathogens plasma membranes.
What are the cells that present antigens to T cells within the adaptive immunity?
Antigen- presenting cells (APCs). T cells must interact with APCs that display antigens for which they are specific in order for T cells to be activated to generate antigen specific responses
What are dendritic cells?
They are antigen presenting cells (APCs), which enables them to trigger adaptive immune responses carried out by T cells. They also have the ability to phagocytize pathogens and other antigens.
In what way do cells of the innate immune system initiate their host defense mechanism?
Pattern recognition
What is pattern recognition?
The ability of innate cells and specific mediators they produce to recognize and respond to evolutionary conserved microbial structures termed pathogen- associated molecular patterns (PAMPs).
How are PAMPs detected in the innate immune system?
Via soluble and cell- associated germline- encoded pattern recognition receptors (PRRs), which are mainly expressed by antigen presenting cells such as macrophages and dendritic cells.
How are pattern recognition cells connected to the adaptive immune response?
Upon recognition of foreign antigen, particularly in the presence of PAMPs, dendritic cells help to initiate an adaptive immune response by B cells and T cells.
What are Toll- Like Receptors (TLRs)?
Pattern recognition receptors (PRRs). A class of proteins that play a key role in the innate immune system. They recognize specific microbial molecular patterns.
Where are TLRs within the cell?
Expressed as membrane- bound or cytoplasmic receptors. TLR1, 2, 4, 5, and 6 receptors are primarily expressed on the plasma membrane where they sense specific molecules on the surface of microbes. TLR3, 7, 8, and 9 traffic from the ER to endolysosomal compartments where they recognize DNA and RNA
What are C- Type Lectin Receptors?
PRRs. Membrane bound receptors that bind to carbohydrates in a calcium dependent manner. They are involved in fungal recognition and the modulation of the innate immune response
How does this complement system work?
Complement proteins circulate in the blood in an inactive form. Each component takes its turn in a precise chain of steps known as the complement cascade. The end products are molecular cylinders called the membrane attack complex (MAC), which are inserted into the cell walls that surround the invading bacteria.
