Video Transcript
How does the nonspecific immune
response compare to the specific response to antigens? (A) The nonspecific response is
slower than the specific immune response. (B) The nonspecific response is
faster than the specific immune response. (C) The nonspecific response
provides protection against future infections but the specific response does
not. Or (D) the nonspecific response
produces more memory cells than the specific immune response.
This question asks us for the
difference between two types of immune responses which work together to help protect
the body from pathogens and substances that appear harmful. Pathogens are biological agents
that cause illness or disease. These biological agents include
viruses and the microorganisms bacteria, fungi, and protists. There are two forms of our immune
system. Their names, specific and
nonspecific immune systems, give us an idea about the differences between them. So let’s review these before taking
another look at our question.
The nonspecific immune response is
also called the innate immune response since it is present from the time you are
born. “Innate” means inborn. It protects against all pathogens
and other foreign and potentially harmful substances in the same way without
specifically targeting one. There are many examples of
nonspecific immunity, for instance, the skin, which acts as a physical barrier
between the body’s tissues and all pathogens from the outside world.
Other parts of the body which
provide a nonspecific immune response include the cough and vomit reflexes, enzymes
in tears, skin oil, mucus, and stomach acid. There are also phagocytic cells
that engulf pathogens by a process called phagocytosis, shown here in the
diagram. These also contribute to specific
immunity by presenting pathogens to lymphocytes.
If the nonspecific immune system
defends against all pathogens and other potentially harmful substances in the same
way, how about the specific immune system? Let’s have a look.
Before we explain how the specific
immune system works, we need to familiarize ourselves with the term “antigen.” Antigens are substances that when
recognized as nonself by the immune system will trigger an immune response. Examples of antigens are pollen,
toxins, and substances on the surface of pathogens or other foreign cells. When talking about the nonspecific
response earlier, we said it defended against pathogens and other harmful
substances. Well, these contain antigens that
trigger the response.
The specific immune system tailors
its attack to a specific antigen. It is also known as the acquired or
adaptive immune system, as it has to build the immunity up over your lifetime, as it
encounters new antigens. This immune system involves the B
and T lymphocytes. When these first encounter an
invading antigen, they have to be activated, clonal selection, before they can
proliferate and produce a population big enough, clonal expansion, to destroy the
antigen.
B lymphocytes produce antibodies
against the antigen, to help prevent it from damaging the body further. T lymphocytes have four main roles,
which depend on the type of T lymphocyte. The roles can be activating other
immune cells, destroying infected cells, producing cytokines, or closing the whole
attack down once the antigen has been destroyed.
Once the cells of the specific
immune response have encountered an antigen, they produce memory cells which remain
in the body to fight future infections against the same antigen. Because the specific immune system
requires the body’s cells to recognize foreign antigens and activate other cells
that aid in immunity, it can take anywhere between five and 10 days for specific
immune responses to occur. On the other hand, nonspecific
immunity responds immediately and usually causes symptoms of infection that you are
familiar with like fever.
After reviewing the differences
between specific and nonspecific immune responses, we can return to our question and
narrow down our choices.
We now know that it is only the
specific immune response that produces memory cells. So we can rule out options (C) and
(D). We also know that the specific
immune response requires time for recognition and proliferation of immune cells in
response to an antigen, while the nonspecific immune response is almost
immediate.
Therefore, the correct answer to
our question “how does the nonspecific immune response compare to the specific
response to antigens?” is answer choice (B). The nonspecific response is faster
than the specific immune response.
