I&I development of immune cells Flashcards
What are the main cells of the immune system?
-Granulocytes
–neutrophils, basophils, eosinophils, mast cells
-Monocytes & Macrophages
-Dendritic cells
-Lymphocytes (T cells, B cells)
-NK cells
What are the 2 specific lineages in immune cell development?
-Myeloid lineage
-Lymphoid lineage
What is the origin of phagocytes?
Myeloid lineage
What cells included as phagocytes?
Neutrophils, macrophages, dendritic cells and antigen presenting cells
What cells are derived from the myeloid lineage?
Mast cells, eosinophils and basophils
What cells are derived from the lymphoid lineage?
Natural killer cells
What multipotent progenitor does the myeloid lineage cells come from?
Common myeloid progenitor
What multipotent progenitor does the lymphoid lineage cells come from?
Common lymphoid progenitor
What does the common lymphoid progenitor branch into before the final cells of the lymphoid lineage?
- T, NK cells and Pro-B
–Give rise to NK cells, T cells and B cells
What is the fate of granulocytes and monocytes?
Circulate in the blood and are recruited at sites of infection/tissue damage
What is the fate of resident APCs(dendritic cells and macrophages)?
stationed in all
organs and especially at portals of pathogen entry (skin,
airways, gut, etc.) to detect invaders
Where do immature T cells mature?
Immature T cells enter thymus where they continue maturation until the stage of mature naive T cells
Where do immature B cells mature?
Immature B cells continue maturation in the bone
marrow until the stage of mature naive B cells
What are immature lymphocytes tested for?
Immature lymphocytes are ‘tested’ for ability to:
- recognise self MHC-I and II (T cells) -useful
- respond to self Ags - not useful & dangerous
What are the stages in T cell maturation?
- Stem cell
- Double negative(CD4-CD8-)Pro-T cell
- Pre-T cell with a Pre-TCR(receptor)
- Double positive(CD4+CD8+)immature T cell
- If there is weak recognition of class II MHC + peptide we get mature CD4+ T cell. This is positive selection.
- If there is weak recognition of class I MHC+ peptide we get mature CD8+ T cell. This is positive selection
- If there is no recognition of MHC+ peptide then leads to apoptosis. This is because of a failure of positive selection(death by neglect)
- If there is strong recognition of either class I or II MHC + peptide then leads to apoptosis. This is due to negative selection
Stages in B cell maturation and selection
See slide 19