1. Cells of the Immune System Flashcards
Which cells are involved in community?
Leucocytes, endothelial cells, adipocytes and epithelial cells
What is the typical lineage of immune cells?
Start as self renewing stem cells, differentiate into pluripotent stem cells influenced by growth factors, and become progenitor cells
What are the progenitor cells for leucocytes?
Myeloid cells (derive from bone marrow) and lymphoid cells (derive from the lymphatic system)
What is the innate immune response?
An immediate response to pathogens, prioritises recovery and clearing pathogens from the body, mainly involves phagocytes and RBCs
What is the adaptive immune response?
Takes longer to develop, Focuses on memorisation of antigens and antibodies, mainly involves lymphocytes
What are stem cells?
Single cells that can replicate itself and/or differentiate into a variety of cell types
What specific cells can be derived from the myeloid lineage?
Erythrocytes, platelets, granulocytes (basophils, eosinophils, neutrophils) monocytes and macrophages (to some extent dendritic cells)
What are two growth factors and hormones that Determine which lineages the progenitor cells develop into?
Cytokines or interleukins and colony stimulating factors
What specific cells can be derived from the lymphoid lineage?
Lymphocytes (B cells and T cells), natural killer cells, innate lymphoid cells and natural killer T cells (to some extent dendritic cells)
What is the connection between monocytes and macrophages?
Monocytes are present in the blood and bone marrow but become macrophages when in the tissues
Which cell of the immune system has an unknown lineage or developmental stage?
Mast cells
What are two growth factors and hormones that determine which lineage stem cells develop into the bone marrow?
Cytokines or interleukins and colony stimulating factors
Where do blood cells in the bone marrow migrate into in order to differentiate further and act?
Tissues (lymphocytes, granulocytes, mast cells, macrophages), blood (monocytes, erythrocytes, lymphocytes, natural killer cells, platelets), secondary lymphoid tissues (macrophages, dendritic cells, lymphocytes), thymus (T cells)
Where does cell generation occur in developing foetuses? Why?
Liver – bone marrow is not large enough to support the amount of generation
What are the cell-surface markers for T cells? What isn’t present?
CD3. No CD19, CD21 or CD14
What are the cell-surface markers for B cells? What isn’t present?
CD19 and CD21. No CD3 or CD14
What are the cell-surface markers for monocytes? What isn’t present?
CD 14 (and 15). No CD3, CD19 or CD21
What is the CD system?
The cluster of differentiation system is a strict nomenclature for how to describe the specific surface markers to identify cells
What are polymorph cells?
Polymorphonuclear cells have a nucleus of many shapes
What is the precursor of platelets cells?
Megakaryocytes
What is the major component of white blood cells?
Granulocytes — 60-70%
What do polymorphs include?
Basophils, eosinophils and neutrophils (granulocytes)
What is the major component of granulocytes?
Neutrophils — 90%
Why are neutrophils given their name?
They contain neutral (pink) staining cytoplasmic granules that secrete enzymes such as lysozyme and neutrophil extracellular traps
What do neutrophils protect the body against?
They kill bacteria via phagocytosis. It is the most important cell in non-viral infections
Why are eosinophils given their name?
Contain granules that stain red with eosin As well as a crystalline core of eosinophil basic protein with cytotoxic properties
What do eosinophils protect the body against?
Parasites. Most important cell for helminth (worm) infections
Why are basophils given their name?
Contain basic granules that stain deep purple
What do basophils protect the body against?
Allergic reaction – promote information and do not phagocytose
Where are mast cells found?
Circulate in the bloods as immature cells. Found in connective and mucosal tissues as mast cells (sentinel cells that exist and wait for when they are needed)
What do mast cells protect the body against?
Important an allergy – release activating factors such as histamine and have IgE receptors
What are the structural differences between monocytes and macrophages?
Monocytes ammonia nuclear and kidney bean shaped. Macrophages are up to 10 times larger
What are some microbicidal mechanisms of monocytes and macrophages?
Secrete growth factors, chemicals, enzymes and activation factors to recognise and engulf pathogen is as well as present it’s antigens on their own cell surface
What are the major two subgroups of monocytes and macrophages?
M1 and M2
Type of macrophage in the liver
Kupffer cells
Type of macrophage in connective tissue
Histiocytes
Type of macrophage in the lungs
Alveolar macrophages
Type of macrophage in the kidneys
Mesangial cells
Type of macrophage in the brain
Microglial cells
Type of macrophage in the bona
Osteoclasts
Explain the mechanism of dendritic cells
When immature dendritic cells capture antigens and migrate to lymphoid tissue where they mature and present these antigens to T cells
Subtypes of dendritic cells
Langerhan cells on skin, interdigitating and plasmacytoid
Polyploidy meaning
Carrie several different copies of their genetic material in order to replicate quickly
Describe platelets
Anucleated, contractile, adhere to other cells and surfaces and important in blood coagulation
What occurs after antigen stimulation in lymphoid progenitor cells?
Cells can differentiate into affect the cells or memory cells – vaccines are based on this principle
What is tolerisation /education?
Lymphocytes are taught to not recognise an act on self molecules. This occurs in the bone marrow for B cells and the thymus for T cells
Plasma cells
Activated be lymphocytes that secrete antibodies
Sub-groups of T cells and their surface markers
Helper (CD4+) and cytotoxic (CD8+)
Helper T cells
Activated by antigen presenting cells. Secrete cytokines to help immune responses by cell communication or become memory cells
In which organelle are antibodies manufactured within the cell?
The ER
Cytotoxic at cells
Kill infected targets or tumour cells By releasing perforans and Gran zymes to induce apoptosis or become memory cells
Perforins
Punch holes in infected cells to destroy them
Granzymes
Induce apoptosis
Regulatory T cells
Affects the immune response by suppressing or activating it through direct cell contact or by the secretion of soluble factors
Natural regulatory T cells
T cells from the thymus. Destined
Inducible regulatory at cells
T cells in the periphery. Activated
Gamma-delta T cells
Strange T cells. T-cell receptor of a gamma and Delta chain rather than alpha and beta chain and contains CD8 and CD4 surface markers. Recognises lipid antigen is highly prevalent in the mucosal tissues
What is the TCR usually composed of?
Alpha and beta chain
Large granular lymphocytes
Similar to lymphocytes but are larger and have a granular cytoplasm. Kill certain tumour and viral infected cells and have helper functions in skin and mucosal surfaces
What are the two main groups of an innate lymphoid cells?
Natural killer T cells and natural killer/innate lymphoid cells
Natural killer T cells
Kill target cells similarly to cytotoxic T cells and make growth factors and signalling molecules similar to helper T cells. Have T cell receptors and CD3 markers but no CD4 or CD8 markers
What are targets for NKT cells?
Tumour cells, virally infected cells, bacteria infected cells
Natural Killer cells
Recognise self and a non-self structures that activate or suppress their activity including growth factors and antibodies. Do not have a TCR
Innate lymphoid cells
Secrete cytokines similarly to helper T cells and regulatory T cells. Mainly active innate immune responses. Do not have a TCR or CD3, 4 or 8 markers