<< Chapter < Page Chapter >> Page >
  • Explain the difference between exogenous and endogenous pyrogens.
  • How does a fever inhibit pathogens?

Resolution

Given her father’s premature death, Angela’s doctor suspects that she has hereditary angioedema , a genetic disorder that compromises the function of C1 inhibitor protein. Patients with this genetic abnormality may have occasional episodes of swelling in various parts of the body. In Angela’s case, the swelling has occurred in the respiratory tract, leading to difficulty breathing. Swelling may also occur in the gastrointestinal tract, causing abdominal cramping, diarrhea, and vomiting, or in the muscles of the face or limbs. This swelling may be nonresponsive to steroid treatment and is often misdiagnosed as an allergy.

Because there are three types of hereditary angioedema, the doctor orders a more specific blood test to look for levels of C1-INH, as well as a functional assay of Angela’s C1 inhibitors. The results suggest that Angela has type I hereditary angioedema, which accounts for 80%–85% of all cases. This form of the disorder is caused by a deficiency in C1 esterase inhibitors, the proteins that normally help suppress activation of the complement system. When these proteins are deficient or nonfunctional, overstimulation of the system can lead to production of inflammatory anaphylatoxins, which results in swelling and fluid buildup in tissues.

There is no cure for hereditary angioedema, but timely treatment with purified and concentrated C1-INH from blood donors can be effective, preventing tragic outcomes like the one suffered by Angela’s father. A number of therapeutic drugs, either currently approved or in late-stage human trials, may also be considered as options for treatment in the near future. These drugs work by inhibiting inflammatory molecules or the receptors for inflammatory molecules.

Thankfully, Angela’s condition was quickly diagnosed and treated. Although she may experience additional episodes in the future, her prognosis is good and she can expect to live a relatively normal life provided she seeks treatment at the onset of symptoms.

Go back to the previous Clinical Focus box.

Key concepts and summary

  • Inflammation results from the collective response of chemical mediators and cellular defenses to an injury or infection.
  • Acute inflammation is short lived and localized to the site of injury or infection. Chronic inflammation occurs when the inflammatory response is unsuccessful, and may result in the formation of granulomas (e.g., with tuberculosis) and scarring (e.g., with hepatitis C viral infections and liver cirrhosis).
  • The five cardinal signs of inflammation are erythema , edema , heat, pain, and altered function. These largely result from innate responses that draw increased blood flow to the injured or infected tissue.
  • Fever is a system-wide sign of inflammation that raises the body temperature and stimulates the immune response.
  • Both inflammation and fever can be harmful if the inflammatory response is too severe.

Fill in the blank

A(n) ________ is a walled-off area of infected tissue that exhibits chronic inflammation.

granuloma

Got questions? Get instant answers now!

The ________ is the part of the body responsible for regulating body temperature.

hypothalamus

Got questions? Get instant answers now!

Heat and redness, or ________, occur when the small blood vessels in an inflamed area dilate (open up), bringing more blood much closer to the surface of the skin.

erythema

Got questions? Get instant answers now!

Short answer

Differentiate exogenous and endogenous pyrogens, and provide an example of each.

Got questions? Get instant answers now!

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Microbiology' conversation and receive update notifications?

Ask