Zusammenfassung der Ressource
B and T cells
- Humoral responce
- Is activated when the infection is no in any cell
- Activation phase
- 1. Antigen-presenting cells engulf and breakdown antigens that are invading the host
organism via the usage of Lysozyme
- 2. Broken down antigens combine with MHC 2 proteins and are presented to the surface of the APC
- 3. Helper T cells recognise the MHC-2 and antigen complex and bind to the APC
- 4. The binding activates the APC to release cytokines that activate the Helper T cell
- 5. The activated helper T cell then releases cytokines that help it proliferate causes more T cells
to be made with the specific MHC-2 complex receptor
- Effector phase
- 6. A B-cell with an igm-receptor that corresponds to the antigen attaches to the pathogen
- 7. The antigen is then engulfed with the receptor and they are both degraded via lysozyme
- 8. The MHC-2 and antigen bind to form the MHC-2 complex and are presented onto the surface of the B-cell
- 9. The helper T-cell and B-cell bind causing the helper T-cell to release cytokines
that cause the B-cell to proliferate into many identical B-cells
- 10. The new B-cells either form plasma cells or memory cells
- 10.1. Plasma cells release antibodies that are specific to the antigen present and
bind to the antigen via lock and key for killer cells to attach, engulf and breakdown
- 10.2. Memory cells remain after the infection is treated incase the antigen attacks again
- Cellular Responce
- Activation Phase
- 1. Antigen-presenting cells engulf and breakdown antigens that are invading the host organism via
the usage of Lysozyme
- 2. Broken down antigens combine with MHC 2 proteins and are presented to the surface of the APC
- 3. Whilst this occurs the virus infects epithelial cells, these cells also use lysozyme to
breakdown the antigen and present it with MHC 1 to the surface
- 4. A helper T cell recognises the MHC-2 and antigen complex on the APC
- 5. The helper T cell release singling proteins bringing more and more helper T cells, Cytotoxic T cells (CD8+)
- Effector Phase
- 6. Cytotoxic T cells recognise the MHC1 and antigen complex presented on the endothelial cells and bind to the complex
- 7. The binding causes the release of Perforin, which punches holes into the infected cells causing lysis
- 8. As the infection comes under control regulatory T cells inactivate the Cytotoxic T cells
- 9. Memory T cells remain behind incase the infection begins to attack again
- Is activated when a cell is already infected
- B cells
- General Facts
- 15% of lymphocytes
- Matures in bone marrow
- Generally need T cells for activation
- Effective antigen presenting cells
- Antigen recognition
- MHC 2 is unregulated
- Anti CD40 induce B cells response to Ab-Ag + IL-4= mimics T cell
- No further signal from IL-4 or BCR = cell death
- B cell after differentiation into plasma cells helped by T
cells, become Antibody factories
- T cells
- General facts
- Two types
- CD4+ 65%
- CD8+ 35%
- Originates in bone marrow but matures in the thymus
- After negative and positive selection at the thymus they acquire
the capacity to distinguish self from non self.
- Antigen recognition
- The combination of TCR binding peptide with either the
MHC 1 or MHC 2 allows the T cell to recognise antigens
- For recognition TCR must bind with other accessory
proteins to make a TCR complex
- The signal is not transduced by the TCR but by the accessory proteins,
which causes a cascade of events causing cell action
- T cell receptors recognize peptides only when they are presented by the MHC