Download Question bank-6 –B-cell activation Q1 Explain briefly the fallowing

Question bank-6 –B-cell activation
Q1 Explain briefly the fallowing :
a. Adaptive displays four characteristic attributes..
1-Antigenic specificity:
The antigenic specificity of the immune system permits it to distinguish
subtle differences among antigens. Antibodies can distinguish between two
protein molecules that differ in only a single amino acid.
2- Diversity:
The immune system is capable of generating tremendous diversity in its
recognition molecules, allowing it to recognize billions of unique structures
on foreign antigens.
3- Immunologic memory:
Once the immune system has recognized and responded to an antigen, it exhibits
immunologic memory; that is, a second encounter with the same antigen induces a
heightened state of immune reactivity. Because of this attribute, the immune
system can confer life-long immunity to many infectious agents after an initial
encounter.
4-Self/non self recognition:
Finally, the immune system normally responds only to foreign antigens, indicating
that it is capable of self/non self recognition. The ability of the immune system to
distinguish self from non self and respond only to non self molecules is essential, for,
as described below, the outcome of an inappropriate response to self molecules can
be fatal.
The antigenic specificity of the immune system permits it to distinguish subtle b
b-cell diversity Generation of B cell diversity:
•
The number of different antibodies that can be produced by human body
seems to virtually
•
limitless.
Instead of containing a single complete gene, Ig heavy chain and light chain
loci consist of families of gene segments ,each set of segments containing
alternative version of parts of the immunoglobulin variable regions.
b. Immunobiological function of b_cell .
1. Antigen presenting cells .
2. Producing of antibodies .
Q2 Choose the correct sentences.
Complete the following :
1. Adaptive immunity is not independent of innate immunity. The phagocytic
cells crucial to nonspecific immune responses are intimately involved in
activating the specific immune response.
2. various soluble factors produced by a specific immune response have been
shown to augment the activity of these phagocytic cells. As an inflammatory
response develops, for example, soluble mediators are produced that attract
cells of the immune system differences among antigens.
3. Antibodies can distinguish between two protein molecules that differ in
only a single amino acid.
4. An effective immune response involves two major groups of cells: T
lymphocytes and antigen-presenting cells.
5. Lymphocytes are one of many types of white blood cells produced in the
bone marrow by the process of hematopoiesis .
6. Lymphocytes leave the bone marrow, circulate in the blood and lymphatic
systems, and reside in various lymphoid organs.
7. Because they produce and display antigen binding cell-surface receptors,
lymphocytes mediate the defining immunologic attributes of specificity,
lymphocytes mediate the defining immunologic attributes of specificity,
diversity, memory, and self/nonself recognition.
8. B lymphocytes mature within the bone marrow; when they leave it, each
expresses a unique antigen-binding receptor on its membrane This antigenbinding or B-cell receptor is a membrane-bound antibody molecule.
9. When a naive B cell (one that has not previously encountered antigen) first
encounters the antigen that matches its membrane bound antibody, the
binding of the antigen to the antibody causes the cell to divide rapidly; its
progeny differentiate into memory B cells and effector B cells called plasma
cells.
10. Plasma cells produce the antibody in a form that can be secreted and have
little or no membrane-bound antibody. Although plasma cells live for only
a few days, they secrete enormous amounts of antibody during this time.
11. It has been estimated that a single plasma cell can secrete more than 2000
molecules of antibody per second.
12. Secreted antibodies are the major effector molecules of humoral
immunity.
13. B cells adhesion highly efficient antigen-presenting cells.
14. The primary B cell response leads to production of mainly low-affinity IgM
antibodies.
15. some responding B cells undergo heavy chain class switching and V region
somatic mutation to produce higher-affinity IgG, IgA or IgE anti-bodies.
Memory B cells are selected from this latter population.
16. This interaction induces activation of the B-cells re-encounter their specific
antigen ,they rapidly produce high-affinity IgG, IgA or IgE . This requires
fewer T helper cells and lower levels of lymphokines than the primary
response.
Q3 Explain in diagram the following
a. Activation of B-cell.
2Diversity:
The immune system is capable of generating tremendous diversity in its b
B
B
B
b- Isotype switching of immunoglobulin class
recognition molecules, allowing it to recognize billions of unique structures on
c- Primary and secondary immune response
2- Di
The immune system is capable of generating tremendous diversity in its recognition
molecules, allowing it to recognize billions of unique structures on foreign antigens.
The antigenic specificity of the immune system permits it to distinguish subtle
differences among antigens. Antibodies can distinguish between two protein molecules
that differ in only a single amino acid.
2- Diversity:
The immune system is capable of generating tremendous diversity in its recognition
molecules, allowing it to recognize billions of unique structures on foreign antigens.
nic specificity of the immune system permits it to distinguish subtle differences among
antigens. Antibodies can distinguish between two protein molecules that differ in only a
.single amino acid
:Diversity -2
The immune system is capable of generating tremendous diversity in its recognition
molecules, allowing it to recognize billions of unique structures on foreign antigens.
The antigenic specificity of the immune system permits it to distinguish subtle
differences among antigens. Antibodies can distinguish between two protein
molecules that differ in only a single amino acid.
2- Diversity:
The immune system is capable of generating tremendous diversity in its
recognition molecules, allowing it to recognize billions of unique structures on
foreign antigens.
our
characteristic attributes