Lecture 2 - Cells of the Immune System Flashcards
What are Cytokines?
Cytokines are proteins made by cells that affect the behavious of other cells - often called ‘interleukins’, act via specific receptors on the target cell.
They often require cell to cell contact.
What are Chemokines?
Chemokines are small proteins that stimulate the migration of cells - chemoattractants.
They are critical in inflammation, they act on lymphocytes and phagocytic cells.
Describe the process of haematopoiesis.
Haematopoiesis is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells.
Where do Haematopoietic stem cells reside?
Haematopoietic stem cells reside in the bone marrow and have the ability to give rise to all of the different mature blood cell types and tissues. HSCs are self-renewing.
What lineages are blood cells divided into?
Erythroid Cells
Lymphocytes
Myelocytes
Which cells make up the Erythroid cells?
Erythroid cells are the oxygen carrying red blood cells. Both reitculocytes and erythrocytes are functional and are released into the blood.
What cells make up the Lymphocytes?
Lymphocytes are the cornerstone of the adaptive immune system. They are derived from common lymphoid progenitors. The lineage is primarily composed of T-cells and B-cells.
What cells make up the Myelocytes?
Myelocytes, which include granulocytes, megakaryocytic and macrophages are derived from common myeloid progenitors, are involved in such diverse roles as innate immunity, adaptive immunity and blood clotting.
Describe the process of asymmetric division with regards to HSCs.
When HSCs proliferate, at least some of their daughter ells remain as HSCs, so the pool of stem cells does not become depleted. The other daughters of HSCs (myeloid and lymphoid progenitor cells) can commit to any of the alternative differentiation pathways that lead to the production of one or more specific types of blood cells.
What percentage of WBC are monocytes responsible for?
3-8% of WBC are monocytes.
What activates monocytes?
Monocytes through an encounter with a pathogen but also cytokines from T cells (IFN-gamma).
When macrophages are activated what do they become better at?
Activated macrophages become better at…
phagocytosis
antigen presentation
increased secretion of inflammatory mediators
better at killing
What are Monocytes?
Leukocytes of the mononuclear phagocyte lineage are called monocytes. These cells migrate from the blood into the tissues where they develop into tissue macrophages.
Where do monocytes develop into macrophages?
Monocytes migrate from the blood into the tissues where they develop into tissue macrophages.
What are Neutrophils?
Neutrophils are a group of phagocytes that make up the majority of the blood leukocytes and develop from the same early precursors as monocytes and macrophages.
Neutrophils migrate into tissues, particularly at the sites of inflammation. They are short lived cells that phagocytose material, destroy it, and then die within a few days.
