Lecture 1. Basis of immunology (AM_470656)

Molecular Cell Biology and Immunology
Lecture 1. Introduction to immunology
INDEX

1. Cells of the immune system .................................................................................................................................................... 2
1.1. hematopoiesis................................................................................................................................................................. 2
2. Activation of the Innate and Adaptative immune system ....................................................................................................... 3
2.1. Adaptative immune response ......................................................................................................................................... 4
2.2. Infection .......................................................................................................................................................................... 4
2.3. Dendritic cells ................................................................................................................................................................. 4
2.4. Initiation of the adaptative response .............................................................................................................................. 5
3. Complement system ............................................................................................................................................................... 5
3.1. Characteristics ................................................................................................................................................................. 5
3.2. Activation of the complement system ............................................................................................................................. 5
4. B and T cell receptors .............................................................................................................................................................. 6
4.1. B cell receptor ................................................................................................................................................................. 6
4.2. T cell receptor ................................................................................................................................................................. 6
4.3. Reg-enzymes ................................................................................................................................................................... 6
4.3.1. In B cells ........................................................................................................................................................................... 7
4.3.2. In T cells ........................................................................................................................................................................... 7
5. MHC class I and II presentation............................................................................................................................................... 7
5.1. The anchor system .......................................................................................................................................................... 8
6. Activation of T and B cells ....................................................................................................................................................... 8
6.1. T cell effector functions and effector molecules .............................................................................................................. 9
6.2. B cell activation ............................................................................................................................................................. 10
6.3. Plasma cell formation ................................................................................................................................................... 10
7. Antibody effector functions .................................................................................................................................................. 10
7.1. Transport ...................................................................................................................................................................... 10
7.2. Neutralising antibodies ................................................................................................................................................. 12
9. Mucosal immune system ...................................................................................................................................................... 12
9.1. Beneficial role of the microbiome ................................................................................................................................. 13
9.2. Systemic and mucosal immune response ...................................................................................................................... 13
10. Summary ............................................................................................................................................................................ 14




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, 1. CELLS OF THE IMMUNE SYSTEM

1.1. HEMATOPOIESIS

It all starts with the hematopoietic cell that can divide into (1) lymphoid precursor and (2) myeloid precursor. This cells can later
differentiate (image).

• The lymphoid precursor can become:
o NK/T cell precursor, that later becomes a T or NK cell.
o The lymphoid also becomes a B cell.
• The myeloid precursor becomes:
o Megakaryocyte/erythroid progenitor that becomes erythrocytes or platelets. They are not technically part of
the immune system but they are derived from precursors of the immune system.
▪ Platelets are involved in clotting but they can also secrete cytokines that seem to have a small
immunological function but is not very clear.
o It can become a granulocyte-macrophage progenitor, that can form the macrophage, dendritic cell (DC),
neutrophil, eosinophil and basophil.
▪ Mast cells are unknown where they come from but they are in the tissue, the precursor not understood.

The adaptative immune system (IS) is formed by B and T cells. The rest is innate IS.




Innate and adaptative immunity fight pathogens in different ways:

• Innate is:
o Fast, within hours.
o It is fixed, meaning they can recognize patterns on pathogens with patter recognition receptors. They are not
very specific; with a molecule expressed but eh pathogen it can be recognized by the IS.
o It does not change with the response; it helps to fight pathogens but it is simpler.
• Adaptative
o Slow, it needs a week or two to become mature. That is why we need the innate, to fight the pathogen until the
adaptative has been developed.
o The development occurs for every pathogen. Selective and specific for every pathogen.
▪ It becomes better the longer the process takes. B, T and antibodies become better, the memory
response too.
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