Foreign Invaders
Cytokines are produced by cells in response
Innate responce example with splinter
Major Histocompatibility Complexes (MHC) Pathways deliver short peptides to the cell surface so that these proteins can be recognized by T-cells
Cytokines induce biological effects through intracellular signalling cascades which lead to changes in gene expression
This influences both innate and adaptive immune responses
Can bind to receptors on the same cell (autocrine), neighbouring cells (paracrine), or distant cells (endocrine) to cause biological changes
This is accomplished through various cytokine activities:
3) Antagonistic - inhibition of one cytokines effects by another
4) Synergic - Cooperative effects of multiple cytokines
2) Redundant - Multiple cytokines have the same effect
5) Pleiotrophy - Different effects on different types of target cells
1) Cascade induction - Multistep mechanism for the amplified production of a given cytokine
Different families of cytokines exist based on their structure and purpose:
3) Interferon - Involved in anti-viral responses and modulates immune responses
4) Tumor Necrosis - Regulates various activities
2) Hematopoietin - Diverse functions
5) IL-7 - Promotes inflammation
1) IL-1 - Promotes inflammation
6) Chemokines - Chemoattractants
Direct white blood cells to infection site. Chemotaxis creates a chemical gradient that drives cell movement
2 classes of MHC exist and have different functions
1) MHC class I molecules
2) MHC class II molecules
Cytosolic (exogenous) pathway
Endocytic pathway
Cross presentation: Exogenous antigens can be presented by MHC class I molecules and endogenous antigens can also be presented by MHC class II molecules
Includes viral peptides
Proteins degraded by proteasome and transported to the rough ER via TAP
Peptides bond to the MHC class I molecule with the help of chaperones and are transported to the plasma membrane
Antigen is internalized in endocytic vesicles and broken down into small peptides
These molecules are first assembled in the ER
Invarient chain guides MHC to vesicles, chain is digested and CLIP binds. CLIP is then exchanged for antigenic peptide, facilitated by HLA-DM. The MHC molecule and antigenic peptide are then brought to the plasma membrane
3) Injured cells release histamines causing blood vessels to dilate, resulting in swelling
2) Bacteria from splinter invade epidermis and multiply
1) Epithelial barrier is broken by splinter
When bacteria invade, epithelial cells are activated and produce cytokines
4) Neutrophils migrate towards bacteria by sliding through blood vessel walls and destroy foreign bacteria by phagocytosis. This results in apoptosis of neutrophils