The clonal selection hypothesis has become a widely accepted
model for how the immune system responds to infection
and how certain types of B and T lymphocytes are selected for destruction of specific antigens invading the body.
What is the purpose of clonal selection?
Clonal selection is a process proposed to
explain how a single B or T cell that recognizes an antigen that enters the body is selected from the pre-existing cell pool of differing antigen specificities and then reproduced to generate a clonal cell population that eliminates the antigen
.
Why is clonal selection of B cells important?
Clonal selection is a theory stating that
B cells express antigen-specific receptors before antigens are ever encountered in the body
. ... Following the initial infection, random mutations during clonal selection could produce memory B cells that can more easily bind to antigens than can the original B cells.
What does the clonal selection theory explain?
Clonal selection theory illustrates
how immunological memory permits a rapid response upon a second exposure to an antigen
. Immunological memory is the basis of natural immunity and artificial immunity (from vaccinations). Each B cell has a specific antibody as a cell surface receptor.
What is the example of clonal selection?
For example,
memory B cells that differentiate after an adaptive immune response
are thought to undergo clonal selection so that antibodies produced by newer memory B cells have considerably higher binding affinities to their antigens.
What are characteristics of clonal selection?
Clonal selection involves two main concepts i.e., are
cloning and affinity maturation
. More precisely, it establishes the idea that only those cells capable of recognizing an antigen will proliferate, while other cells are selected against. Clonal selection calls both B and T cells.
How does clonal selection occur?
Clonal selection is the theory that specific
antigen receptors exist on lymphocytes before they are presented with an antigen due to random mutations during initial maturation and proliferation
. After antigen presentation, selected lymphocytes undergo clonal expansion because they have the needed antigen receptor.
What is responsible for initiating clonal selection?
Lymphocytes. C. The lymphocytes remain dormant until
an antigen
initiates clonal selection.
What occurs during clonal deletion?
Clonal deletion is the
removal through apoptosis of B cells and T cells that have expressed receptors for self before developing into fully immunocompetent lymphocytes
. This prevents recognition and destruction of self host cells, making it a type of negative selection or central tolerance.
Is clonal anergy reversible?
Clonal anergy is another mechanism of peripheral tolerance to self-antigens. In the context of oral tolerance, its involvement was first demonstrated based on a study that showed
T cell tolerance could be reversed in vitro by exogenous
IL-2 (Whitacre et al., 1991).
What is meant by clonal?
1.
A group of cells or organisms that are descended from and genetically identical to a single progenitor
, such as a bacterial colony whose members arose from a single original cell.
Which type of immunity is the shortest lasting?
Passive immunity
is short lived, and usually lasts only a few months, whereas protection via active immunity lasts much longer, and is sometimes life-long.
What is immune selection?
Immune responses
that kill pathogens or reduce their reproductive rate
are generally important in protecting hosts from infection and disease. Pathogens that escape the full impact of such responses will survive, and any heritable genetic basis of this evasion will be selected.
What is the first step of clonal selection?
1: Clonal Selection, Step-1. During its
development, each B-lymphocyte becomes genetically programmed, through a process called gene translocation
, to make a unique B-cell receptor. Molecules of that B-cell receptor are placed on its surface where it can react with epitopes of an antigen.
Which of the following plants clonal selection is done?
Clonal selection is the method of selection of desirable clones from the mixed population of vegetatively propagated crops. It is one of the methods for improving the vegetatively propagated crops such as
sugarcane, banana, potato, citrus, mango
, etc.
What is meant by clonal expansion?
Abstract. Clonal expansion of lymphocytes is a hallmark of
vertebrate adaptive immunity
. A small number of precursor cells that recognize a specific antigen proliferate into expanded clones, differentiate and acquire various effector and memory phenotypes, which promote effective immune responses.
