1.1. What is the central idea of the clonal selection hypothesis?
1.1. Lymphocytes mature in absence of antigens, by gene-translocation 10^9 variations of antigens can be recognized. Mature lymphocytes sit in lymphoid tissue and come in contact with APCs showing off antigens from infectious sites. They are specific and unique for specific antigens and are activated by a fitting antigen.
1.2. What are cytokines?
1.2. Cytokines: Wide range of small proteins /polypeptides that can't cross blood-brain barrier. Immunomodulation agents - they regulate intensity + duration of immune response. Eg. Interleukins, Interferons, mesenchymal growth factors, TNF, chemokines
Produced by Macrophages, T and B, Mast, endothelial fibroblasts and stromal cells.
1.3. What are the different immunoglobulin classes?
1.3.
IgG - most common in blood and tissue fluids, 4 subclasses, can cross placenta, stable
IgA - saliva, respiratory fluids
IgM - first produced by maturing B cell, mucosal immunity + complemement activation
IgD - unknown function, present on B cell surfaces, rarely secreted
IgE - against helminths, bind to mast cells and basophils, allergy - relation
1.4. Name lymphocyte classes and their roles in immunity
1.4.
B Lymphocytes - antigen recognition on microbes, produce specific antibodies
Helper T L. - Mediate inflammation, activation of other immune cell effectors
Cytotoxic T L. - Induce Apoptosis in infected cells
Regulatory T L. - Suppression of other Lymphocytes (recognize wrongly activated)
1.5. How are infected cells recognized?
1.5.
All cells with a nucleus constantly present parts of proteins (=antigens) that have been degraded in their proteasome to the outside on MHC class I molecules. Other immune effector cells can differentiate self and non-self antigens and react to the latter by inducing apoptosis, inflammation, etc.
1.6.
Dendritic cells: connect innate and adaptive immunity
Different subsets, e.g DC1, DC2, Langerhans cells in the Skin
1.7. What are the key differences between neutrophils and macrophages?
1.7.
-Origin (N and blood M: HSC in bone marrow, tissue resident M: early in development)
-Lifespan (N: 1-2d - M: days-weeks, tissue resident: years)
-Response (N rapid, shortlived - M: more prolonged, slower (often transcriptional))
-Cytokine production major funtion in M
-Degranulation major function in N
-ROS in N; NO in M after transcriptional activation of iNOS
-NET only from N; Pyroptosis only from M by Caspase-1-activation