lecture 31 - immune cells of blood Flashcards
What are the two overall components of blood, and at what ratios?
55% plasma, 45% formed elements
What are the components of plasma?
Proteins (including antibodies/immunoglobulin), other solutes, water
What are the 3 key formed elements of blood?
Platelets, white blood cells (leukocytes), red blood cells
What is the general term for white blood cells?
Leukocytes
What process allows bone marrow stem cells to produce blood cells?
Hematopoiesis.
What are the 3 blood cell lineages?
Erythoid, myeloid, lymphoid
What type of cell are in the Erythroid lineage?
Red blood cells (erythrocytes)
What types of blood cells are in the myeloid lineage? (4)
Granulocytes, monocytes, dendritic cells, platelets
Are blood cells of the myeloid lineage innate or adaptive in nature?
Innate
What types of cells are in the lymphoid lineage?
B and T lymphocytes (B/T cells)
Are cells in the Lymphoid blood cell lineage adaptive or innate in nature?
Adaptive
What two blood cell lineages are white blood cells?
Myeloid and lymphoid
What is the name for granulocytes found in blood?
Neutrophils
What proportion of leukocytes are represented by neutrophils?
75%
What is the structure of a neutrophil?
Has a multi lobed nucleus and contains granules
What is the function of neutrophils?
They highly phagocytic - can ‘eat and kill’ pathogens.
When do neutrophil levels in the blood increase?
When there is infection or inflammation
When can neutrophils move out of blood and into tissue?
When there is inflammation
What is the name for granulocytes found in tissue?
Mast cells
What are mast cells?
Cells that line mucosal surfaces and release granules that attract other white blood cells to areas of tissue damage/infection.
What are monocytes?
Cells present in the blood that have a low level of phagocytosis until they leave the blood and develop into macrophages in tissues.
What are macrophages derived from?
Monocytes
Where are macrophages found?
In tissue - not in blood
Do macrophages have a high or low rate of phagocytosis?
High
What are the possible ways that a macrophage can sit in tissue?
Can become resident/sessile, or move though it (migratory)
What are the 3 functions of macrophages?
Phagocytosis, release of chemical messengers, show info about pathogenic microbes to T cells.
What is phagocytosis?
Ingestion of bacteria by cells such as macrophages
What is the purpose of chemical messaging by macrophages?
Signals to other cells to aid in clearing infection
How do macrophages share information about pathogens?
They break up viruses and attach a piece to a receptor on its surface, where it can be recognised by the adaptive immune system.
How do macrophages link the innate and adaptive immune systems?
They share information about viruses with T cells, activating the adaptive immune system.
What is the function of dendritic cells?
Link innate and adaptive immune systems - they are phagocytic and can present antigens to adaptive immune cells.
Where are dendritic cells found, and in what numbers?
In low numbers in blood and tissues in contact with the environment.
How are immune cells carried around the body?
In blood and in lymph
Where does lymph in tissues collect?
Lymphatic vessels
Where does lymph drain to, from the lymphatic vessels?
Lymph nodes
Where do dendritic cells meet T cells?
Lymph nodes
What does PAMP stand for?
Pathogen associated molecular pattern
What is a PAMP?
A small molecular motif conserved within a class of microbes and are a common ‘building block’.
What are common PAMPS in viruses?
nucleic acids - ssRNA and dsRNA
What are the common nucleic acid PAMPS of viruses?
single stranded RNA and double stranded RNA
What are the locations/types of common bacterial PAMPs?
Cell wall, flagella, nucleic acid
What are the common PAMPs found in bacterial cell walls?
Lipopolysaccharide (LPS), endotoxins, lipoteichoic acid
What are the common PAMPs found in bacterial flagella?
Flagellin
What is the common PAMP found in bacterial nucleic acids?
unmethylated CpG DNA
How do toll-like receptors activate innate immune responses?
Toll-like receptors in the cell membrane recognise PAMPs and can then signal to the nucleus to transcript genes and translate to form proteins that aid in cellular defence.
What intracellular component allows cells to defend against pathogens that have come inside it?
Phagolysosomes
How do phagolysosomes defend cells?
They recognise the nucleic acid PAMPs of invading bacteria/viruses and engulf and decoat them, preventing them from colonising the inside of the cell.
What is the clinical name for fever?
Pyrexia
What is pyrexia?
Fever - an abnormally high body temperature (usually >37 degrees celsius)
What does the fever do to the body’s ‘thermostat’?
Resets the temperature regulation, controlled by the hypothalamus
What substances produce a fever?
Pyrogens
What are pyrogens released by?
Bacteria and immune cells
What chemical messenger and pyrogen is produced by phagocytes?
interleukin-1
What is interleukin-1?
A pyrogen and cytokine
What is the purpose of fever?
Stop pathogen growth and enhance immune function
How does changing phagocytic activity decrease a fever and restore the biological thermostat?
Decreasing phagocytosis leads to a decrease in interleukin-1 release and therefore less pyrogen, so the fever comes down.
What is the difference between lymphocytes and leukocytes?
Leukocytes are all the white blood cells in the blood, while lymphocytes are a specific type of leukocyte that are found in lymph
Are mast cells phagocytic?
Yes
