CELL MEDIATED IMMUNITY AND CYTOKINES |
GUARANTEED SUCCESS STARTS HERE! LEARN,
PRACTICE & EXCEL!
Cellular immunity involves? Answer: Cellular Immunity involves:
- activation of antigen presentation by certain cells
- interaction of antigen-specific T- lymphocytes with other immune cells
- release of various cytokines in response to interaction of immune cells and antigen
What is the T cell response to a particular antigen? Answer: - Depending on the type of
antigen, the T cells will
either kill the infected cell or release cytokines to activate other immune cells.
Positive selection of T cells
how T cell subsets are created Answer: Positive selection of T cells:
1. T cells develop in the bone marrow. Begin as
“double negative” for CD markers 4 and 8.
2. T cells move to thymus to mature
and develop antigen receptors and
become positive for markers 3,4,8)
3. Double positive (CD4/CD8+)
thymocytes are presented with
MHC Class proteins
4. If they do not bind MHC, they die
within the thymus
5. If they can bind the MHC, the T-
cells survive and proliferate.
APPHIA – Crafted with Care and Precision for Academic Excellence.
1
, negative and positive selection Answer: the mechanism used by T cells during maturation
in the thymus to determine if a T cell will recognize MHC proteins in antigen presentation
and whether the T cell will eventually become a CD8 or CD4.
At one point early in maturation, the T cell has both markers on its surface.
Thymocytes the naïve t cell which are the precursor to T cells often die before they become
mature, nearly 95% of the time.
The differences between negative and positive selection: T cell growth/maturation Answer:
Positive selection
The process of going from Double-Positive (Cell carries both CD4+, CD8+ markers) to
Single-Positive( cell carries either one marker or the other).
-Only those T-Cells that recognize Self-MHC are allowed to develop. All others die by
apoptosi
Negative selection:
Those T-Cells that recognize Self-MHC alone or with high affinity are killed because
theywould be self-reactive. This ensures Self-Tolerance
Positive selection includes both what? which are what? Answer: DOUBLE-POSITIVE (CD4
+, CD8 +) cells undergo positive selection
- Some cells will bind to macrophage MHC-II in the thymus. This causes them to retain CD4
and lose the CD8 molecule.
- Other cells will bind to thymic epithelial MHC-I in the thymus. This causes them to retain
CD8 and lose the CD4 molecule
SINGLE POSITIVE (CD4 + or CD8 +) results in either case
DOUBLE-NEGATIVE:
- Cells don't recognize either macrophages or epithelial cells, which makes them die by
apoptosis.
- Positive selection eliminates all (double-negative) cells that don't recognize self
APPHIA – Crafted with Care and Precision for Academic Excellence.
2
GUARANTEED SUCCESS STARTS HERE! LEARN,
PRACTICE & EXCEL!
Cellular immunity involves? Answer: Cellular Immunity involves:
- activation of antigen presentation by certain cells
- interaction of antigen-specific T- lymphocytes with other immune cells
- release of various cytokines in response to interaction of immune cells and antigen
What is the T cell response to a particular antigen? Answer: - Depending on the type of
antigen, the T cells will
either kill the infected cell or release cytokines to activate other immune cells.
Positive selection of T cells
how T cell subsets are created Answer: Positive selection of T cells:
1. T cells develop in the bone marrow. Begin as
“double negative” for CD markers 4 and 8.
2. T cells move to thymus to mature
and develop antigen receptors and
become positive for markers 3,4,8)
3. Double positive (CD4/CD8+)
thymocytes are presented with
MHC Class proteins
4. If they do not bind MHC, they die
within the thymus
5. If they can bind the MHC, the T-
cells survive and proliferate.
APPHIA – Crafted with Care and Precision for Academic Excellence.
1
, negative and positive selection Answer: the mechanism used by T cells during maturation
in the thymus to determine if a T cell will recognize MHC proteins in antigen presentation
and whether the T cell will eventually become a CD8 or CD4.
At one point early in maturation, the T cell has both markers on its surface.
Thymocytes the naïve t cell which are the precursor to T cells often die before they become
mature, nearly 95% of the time.
The differences between negative and positive selection: T cell growth/maturation Answer:
Positive selection
The process of going from Double-Positive (Cell carries both CD4+, CD8+ markers) to
Single-Positive( cell carries either one marker or the other).
-Only those T-Cells that recognize Self-MHC are allowed to develop. All others die by
apoptosi
Negative selection:
Those T-Cells that recognize Self-MHC alone or with high affinity are killed because
theywould be self-reactive. This ensures Self-Tolerance
Positive selection includes both what? which are what? Answer: DOUBLE-POSITIVE (CD4
+, CD8 +) cells undergo positive selection
- Some cells will bind to macrophage MHC-II in the thymus. This causes them to retain CD4
and lose the CD8 molecule.
- Other cells will bind to thymic epithelial MHC-I in the thymus. This causes them to retain
CD8 and lose the CD4 molecule
SINGLE POSITIVE (CD4 + or CD8 +) results in either case
DOUBLE-NEGATIVE:
- Cells don't recognize either macrophages or epithelial cells, which makes them die by
apoptosis.
- Positive selection eliminates all (double-negative) cells that don't recognize self
APPHIA – Crafted with Care and Precision for Academic Excellence.
2
