Lecture 5 Flashcards
What are the key components of the innate immune response?
Barriers, Sentinel cells in tissue, circulating phagocytes and granulocytes, blood proteins, cytokines
Sentinel cells in tissues
Dendritic cells, macrophages, natural killer cells
What do circulating phagocytes and granulocytes do?
Cells that can recognize groups of pathogens (ingest foreign matter)
Examples of circulating phagocytes and granulocytes
Neutrophils, monocytes, eosinophils, basophils
What do blood proteins do?
Mediate inflammation
What do cytokines do?
Signal, stimulate, and regulate the immune response
Barrier: saliva properties
Antibacterial enzymes
Barrier: tears properties
Antibacterial enzymes
Barrier: skin properties
Prevents entry
Barrier: mucus properties
Lining traps dirt and microbes
Barrier: stomach acid properties
Low pH kills harmful microbes
Barrier: “good” gut bacteria properties
Out compete the bad bacteria (kills it)
What are the main sites of interaction between individuals and their environment?
Skin, GI tract, Respiratory tract, and the Genitourinary tract
Role of epithelial cells
Defence against pathogens
What makes up the epithelial barrier?
Tight junction, Mucous, and Keratin layers (physical barrier)
Defensins
Host defence peptides with either direct antimicrobial activity, immune signalling activities, or both
Cathelicidins
A polypeptide that is primarily stored in the lysosomes of macrophages and polymorphonuclear leukocytes
Where do all immune cells originate
Bone marrow
Phagocytes’ objective:
Identify, ingest and destroy pathogens
The role of a Phagocyte
Recognition of microbes (PRR), Ingestion of microbe by phagocytosis, Destruction of ingested microbe, Secretion of cytokines to promote and/or regulate immune response, Recruitment of cells to site of infection
Examples of professional phagocytes
Marcophages and neutrophils
Where are macrophages found?
Present under your skin, tissues in lungs and intestines
Macrophages found in bone:
Osteoclasts
Macrophages found in the central nervous system
Microglia
Macrophages found in connective tissue
Histiocytes
Macrophages found in the chorion villi of the placenta
Hofbauer cells
Macrophages found in the kidney
Mesangial cells
Macrophages found in the liver
Kupffer cells
Macrophages found in the peritoneal cavity
Peritoneal macrophages
Macrophages found in the pulmonary airway
Alveolar macrophages
Macrophages found in the skin
Epidermal and dermal macrophages
Macrophages found in the spleen
Marginal zone macrophages, metallophilic macrophages, red pulp macrophages, and white pulp macrophages
What stages do macrophages exist?
Resting (patrolling mode), activated (antigen presentation mode), hyperactivation (destroyer mode)
Resting macrophage stage
Digest dead/non-functional cells and wound healing
Activated macrophage stage
Upregulation of antigen molecules (MHC 1/2), Invaders are destroyed and pieces are displayed to activate T cells
Hyperactivation macrophages stages
Increased in size to focus on destruction (increased lysosomes)
Neutrophils
Most abundant white blood cells (40-70%) specialized for killing
How long is the life span of a neutrophil
Short (5-7 days)
Monocytes
Circulate in blood to be recruited to sites of infection to mature into macrophages
Where are NK cells found?
Blood, spleen, and liver
What is the role of NK cells
“on call” and recruited to the sites of infection, produced cytokines to help in pathogen defence and activation of macrophages. They destroy infected/cancerous cells/parasites/bacteria/fungi