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By the end of this section, you will be able to:
  • Explain the development of immunological competence
  • Describe the mucosal immune response
  • Discuss immune responses against bacterial, viral, fungal, and animal pathogens
  • Describe different ways pathogens evade immune responses

Now that you understand the development of mature, naïve B cells and T cells, and some of their major functions, how do all of these various cells, proteins, and cytokines come together to actually resolve an infection? Ideally, the immune response will rid the body of a pathogen entirely. The adaptive immune response, with its rapid clonal expansion, is well suited to this purpose. Think of a primary infection as a race between the pathogen and the immune system. The pathogen bypasses barrier defenses and starts multiplying in the host’s body. During the first 4 to 5 days, the innate immune response will partially control, but not stop, pathogen growth. As the adaptive immune response gears up, however, it will begin to clear the pathogen from the body, while at the same time becoming stronger and stronger. When following antibody responses in patients with a particular disease such as a virus, this clearance is referred to as seroconversion (sero- = “serum”). Seroconversion is the reciprocal relationship between virus levels in the blood and antibody levels. As the antibody levels rise, the virus levels decline, and this is a sign that the immune response is being at least partially effective (partially, because in many diseases, seroconversion does not necessarily mean a patient is getting well).

An excellent example of this is seroconversion during HIV disease ( [link] ). Notice that antibodies are made early in this disease, and the increase in anti-HIV antibodies correlates with a decrease in detectable virus in the blood. Although these antibodies are an important marker for diagnosing the disease, they are not sufficient to completely clear the virus. Several years later, the vast majority of these individuals, if untreated, will lose their entire adaptive immune response, including the ability to make antibodies, during the final stages of AIDS.

Hiv disease progression

This graph shows the concentration of HIV viral particles in blood over time in years.
Seroconversion, the rise of anti-HIV antibody levels and the concomitant decline in measurable virus levels, happens during the first several months of HIV disease. Unfortunately, this antibody response is ineffective at controlling the disease, as seen by the progression of the disease towards AIDS, in which all adaptive immune responses are compromised.

Everyday connection

Disinfectants: fighting the good fight?

“Wash your hands!” Parents have been telling their children this for generations. Dirty hands can spread disease. But is it possible to get rid of enough pathogens that children will never get sick? Are children who avoid exposure to pathogens better off? The answers to both these questions appears to be no.

Antibacterial wipes, soaps, gels, and even toys with antibacterial substances embedded in their plastic are ubiquitous in our society. Still, these products do not rid the skin and gastrointestinal tract of bacteria, and it would be harmful to our health if they did. We need these nonpathogenic bacteria on and within our bodies to keep the pathogenic ones from growing. The urge to keep children perfectly clean is thus probably misguided. Children will get sick anyway, and the later benefits of immunological memory far outweigh the minor discomforts of most childhood diseases. In fact, getting diseases such as chickenpox or measles later in life is much harder on the adult and are associated with symptoms significantly worse than those seen in the childhood illnesses. Of course, vaccinations help children avoid some illnesses, but there are so many pathogens, we will never be immune to them all.

Could over-cleanliness be the reason that allergies are increasing in more developed countries? Some scientists think so. Allergies are based on an IgE antibody response. Many scientists think the system evolved to help the body rid itself of worm parasites. The hygiene theory is the idea that the immune system is geared to respond to antigens, and if pathogens are not present, it will respond instead to inappropriate antigens such as allergens and self-antigens. This is one explanation for the rising incidence of allergies in developed countries, where the response to nonpathogens like pollen, shrimp, and cat dander cause allergic responses while not serving any protective function.

Questions & Answers

what's is reganal anatomy
Sose Reply
it is the study of interrelationships between different organs in a certain region of the body e.g abdomen
Taurai
this helps understand how these different organs work together to serve a particular body region
Taurai
hesi Tau
Precious
what is important of anatomy
Musah Reply
it's very important in any field of study or work the nurse who know anatomy well he will do good job
Abdelaziz
Can u please tell me how can I get Vanders mcqs bank
haseeb Reply
Is it possible to code a gene from two different species to come up with a specific trait?
Purityhalo
tissue,organ, system, cell
Amadi Reply
list carpal bones from proximal to distal
Meshack Reply
scaphoid, lunate, triquetrum, pisiform, trepizium, trepizoid, capitate, hamate
Bhuvana
You are right
David
gr8 bro
Daniel
anyone explain lungs valium?
Sajid
when did the roman rule Britain
Rita Reply
what is function of the male respiratory system ?
poonam Reply
need to join this conversation
Collins
It's the same as the female respiratory system. Did you mean reproductive system. If you didn't, its for breathing.
Grace
what does increased glomerular filtration results from
Nancy Reply
what is the difference between cardiovascular and respiratory system
Bokenana Reply
cardiovascular deals with blood,blood vessels and heart while respiratory system deal with gas exchange
Erick
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Erick
just make a class group and have online classes take turns in teaching
maz
send yo app lines so I make a group
Erick
ok
Erick
you're simply saying no to teaching one another
maz
what's an epithelial tissue
Romantic Reply
epithelial tissue are thin tissues that covers all the exposed surfaces of the body
Ireen
is anyone from high school?
Sahil
yes
Sulaiman
Final year
Royleen
med student
brian
South Africa
brian
final year too
brian
INDIA
Sahil
describe the structure of the human body in terms of six levels of organisation
Chulufya Reply
list the muscles of abdomen and their functions
HANNAH Reply
list the neck muscles and their functions
HANNAH
list the thy muscles and their functions
HANNAH
four muscles in facial expression
nah
internal obliques external obliques
Diana
describe flow of blood
osoma Reply
are arteries do pumping action to get are blood flow
isaiah
causes of occasional female muscle weakness and body pain
sammy
hey Venus ulcers description
patrick
what is conduction in the heart occur
Daud Reply
what is anatomy
Prin Reply
anatomy is the study of human body.?
Sittie
anatomy is the study of scientific human body's structure.
Sittie
Anatomy is the study of the structure of the human body and the physical relationship between its constituent parts.
Maina
Anatomy is the study of the structures of body parts
Nepi
what are the principles of public health nursing?
tribel
Anatomy is the scientific study of human body parts .
Shakinah
Anatomy is the study of structure and relationship of the body structure
Stephen
Anatomy is the study of the structure and movement of the human body
renukha
energy generation molecular transport reproduction.
Sarah
Anatomy is the study of budy structures and their relationship.
Denis
Anatomy is the scientific study of human structure
jacinta
Anatomy ie the study of the human body and its functions.
Samuel
anatomy is the study of human body
Nadiiro
is the study of the structure of the body
Nqobile
I thank you guys for your studying.
Gibson
what is the biological meaning of come?
Gibson
anatomy is the study of human structure.
Diana
I need help!!! what are toxic wastes being removed from human urinary system apart from urine?
DAVINA
urea, amonia
Orsine

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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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