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By the end of this section, you will be able to:
  • Explain the advantages of the adaptive immune response over the innate immune response
  • List the various characteristics of an antigen
  • Describe the types of T cell antigen receptors
  • Outline the steps of T cell development
  • Describe the major T cell types and their functions

Innate immune responses (and early induced responses) are in many cases ineffective at completely controlling pathogen growth. However, they slow pathogen growth and allow time for the adaptive immune response to strengthen and either control or eliminate the pathogen. The innate immune system also sends signals to the cells of the adaptive immune system, guiding them in how to attack the pathogen. Thus, these are the two important arms of the immune response.

The benefits of the adaptive immune response

The specificity of the adaptive immune response—its ability to specifically recognize and make a response against a wide variety of pathogens—is its great strength. Antigens, the small chemical groups often associated with pathogens, are recognized by receptors on the surface of B and T lymphocytes. The adaptive immune response to these antigens is so versatile that it can respond to nearly any pathogen. This increase in specificity comes because the adaptive immune response has a unique way to develop as many as 10 11 , or 100 trillion, different receptors to recognize nearly every conceivable pathogen. How could so many different types of antibodies be encoded? And what about the many specificities of T cells? There is not nearly enough DNA in a cell to have a separate gene for each specificity. The mechanism was finally worked out in the 1970s and 1980s using the new tools of molecular genetics

Primary disease and immunological memory

The immune system’s first exposure to a pathogen is called a primary adaptive response    . Symptoms of a first infection, called primary disease, are always relatively severe because it takes time for an initial adaptive immune response to a pathogen to become effective.

Upon re-exposure to the same pathogen, a secondary adaptive immune response is generated, which is stronger and faster that the primary response. The secondary adaptive response    often eliminates a pathogen before it can cause significant tissue damage or any symptoms. Without symptoms, there is no disease, and the individual is not even aware of the infection. This secondary response is the basis of immunological memory    , which protects us from getting diseases repeatedly from the same pathogen. By this mechanism, an individual’s exposure to pathogens early in life spares the person from these diseases later in life.

Self recognition

A third important feature of the adaptive immune response is its ability to distinguish between self-antigens, those that are normally present in the body, and foreign antigens, those that might be on a potential pathogen. As T and B cells mature, there are mechanisms in place that prevent them from recognizing self-antigen, preventing a damaging immune response against the body. These mechanisms are not 100 percent effective, however, and their breakdown leads to autoimmune diseases, which will be discussed later in this chapter.

Questions & Answers

all of the following substance move in in and out of cell except
Mohd Reply
all of the following substance move in and out of cells except
Mohd
Which signaling molecule is most likely responsible for an increase in digestive activity?
Tonya Reply
Hi I think it is DNA
libim
Homeostatasis return to the body to a healthy state after a stressful stimuli by producing
Ofosu Reply
There are some people suffering serious injured what will we do in doing X-ray?
Jefford Reply
observe bone arrangements n associated structures like soft tissues muscles in general the radiographical changes
Terry
epithelial tissue lines blood vessels
Laura Reply
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Chinaza Reply
anabolism simply means building up while catabolism breaking down
Maaruf
building up and breaking down
odeh
explain respiratory centers
Tharshana Reply
which enzyme help in excretion of bile
Sakshi Reply
how conversion of Beta-carotiene into vitamin-A takes place
Sakshi
best reference books for anatomy pls suggest that
Sakshi
what is gross anatomy
Saroj Reply
The study of large structure of the body
Mablean
macroscopic anatomy (Gross anatomy)
odeh
manipulation of structures without aid of microscope due to their size
libim
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Dakshit Reply
a bag of skin near the penis which contains the testicles
Mablean
hi
Sardar
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Sardar
Why are you on my digits
Mablean
hi
Kryme
it is part if male organ that hold testis in position it also regulates temperature
libim
how does it work?
Uriah Reply
I want to know the fertilization process in human
Nana Reply
Which plane divides the body into right and left parts
Kaeze
sagittal plane
Irvin
Thank you
Kaeze
Homestatic regulations usually involves a (n) _ that detects a particular stimulus, and a(n) _that respond to the stimulus by communicating with a (n) _whose activity has an effect on the same stimulus.
Kaeze
A cell is producing proteins to be transported out of that cell. They will be processed on ribosomes that are
Kaeze
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Azoyenime Reply
Haemophilia
Aliyu
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Diabetes insipidus or diabetes mellitus would most likely be indicated by ________.
Ganesh
oral cavity how miean
Ganesh Reply
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Suresh
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Muhammad
they know what to ask the problem is how to ask it.too much broken english.
George
dear George ongeche I think if they ask these kind questions and telling themselves as HCPs or medical student's .these are the basic ones go ask something more interesting .
Muhammad

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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