Study Guide Sheet 2 (pt2) Flashcards
Describe the key composition and activities of helper T-cells.
Helper T-cells use CD4 and LFA-1 to bind to the APC and then signals for Th1 (cell mediated) or Th2 (humoral) to activate the body’s immune response.
Describe the key composition and activities of cytotoxic T-cells
CTL’s use CD8 and LFA-1 (requires IL-2 from T-helper cell) then use serglycin which is composed of perforin and granzymes.
CTL’s kill the target cell and do not get hurt in the process.
Describe how Helper T-cells are activated including cells and cytokines involved.
(a) Contact of TCR with a corresponding epitope bound to the MHC-II on the APC
(b) Binding of ICAM-1 with LFA-1 – adhesion
(c) Binding of CD28 with the CD80/86 on the APC (IL-1 stimulatory co-signal)
(d) Interleukin-1 activation co-signal – initiates growth of T-cell
How are Cytotoxic T-cells activated?
CTL’s are activated by the Th-1 cells, using IL-2. Occurs during the cell-mediated response phase.
How do Cytotoxic T-cells protect the body from invading microbes?
By using serglycin (perforin and granzymes) and causing apoptotic death to the target cells
What are memory cells?
Cells that “remember” the antigen used
What is the overall role of the cell-mediated immunity system?
Provide antigen-specific protection against intracellular viruses, intracellular bacteria, parasites, fungi, tumors, and transplanted organs through the killing function of activated T-cells and NK-cells
In the humoral response, ____-lymphocytes are activated to differentiate into ____________ and produce _____________.
B; Plasma cells; Ig
Describe the activation of the humoral immune system by means of the Helper T-cells in the T-cell dependent method (e.g. which cells and cytokines are involved and which immunoglobulins produced). – Describe the events/results that occur after a B-cell is activated.
- Cytokines involved include IL-4/5/6/10
- Ig produced are IgM and IgG.
- After the B-cell is activated, it can differentiate into plasma cells and produce Ig, or become memory cells.
What is opsonization?
The attachment of immunoglobulin molecules to the surface of an antigen, thus marking the cell for rapid phagocytosis and increasing the phagocyte’s adherence to the cell
Describe the production of IgA
Secretory IgA production begins very soon after stimulation (no difference between primary & secondary responses)
Which Ig(s) can cross the placenta?
Only the IgG
Which Ig(s) activate complement?
IgM and IgG
Which Ig(s) have a potential opsonizing effect?
IgM and IgG
Which Ig provides most of the defense for mucosal areas?
IgA
Which Ig is elicited by parasitic infections?
IgE
Which Ig is produced in the greatest concentration?
IgG
Which Ig is increased during some allergic reactions?
IgE
Which Ig is produced first in sequence from plasma cells?
IgM
Which Ig provides major protection during primary response?
IgM
Which Ig provide major protection during secondary response?
IgG
Describe the function of IgE on mast cells in allergic reactions
Induces the mast cell to degranulate its histamines
Define “complement system”
A complex series of serum proteins which interact in a cascade fashion to enhance certain antigen-antibody reactions. It is activated by presence of certain antigen-antibody complexes (IgG and IgM) on the surface of antigen
State the biological roles/effects of complement
- C3b adheres the phagocyte, and produces C3 - C9 (MAC - Membrane Attack Complex) and results in cytolysis of the antigen
- C5a attracts phagocytes through chemotaxis and the migration of basophils, and eosinophils to the areas of inflammation
Describe the composition of natural killer cells
NK cells possess CD16 and CD56 surface proteins.
