Navigation Links
Leprosy microbes lead scientists to immune discovery

With the unusual opportunity that human leprosy infections provide for study of human immune responses, scientists have discovered how the body's early warning system prompts a rapid immune response by two separate armies of defensive cells. The finding helps explain why, when threatened by microbes like the leprosy bug, this initial defense sometimes succeeds in limiting the damage, but in other cases yields to a dangerous, spreading infection.

Led by Stephan R. Krutzik of UCLA, a team of scientists that includes Barry R. Bloom, Dean of the Harvard School of Public Health, reported the work on May 8 in an advance online publication of Nature Medicine.

The researchers isolated immune cells in blood samples from healthy people and exposed the cells to a component of mycobacteria. The large white blood cells known as monocytes rapidly differentiated into the two distinct cell types, forming the body's emergency response to the detection of foreign bacteria. One category of defensive cells, macrophages, seek out and engulf the infectious bugs. The other group consists of dendritic, or "antigen-presenting" cells, which seize distinctive pieces of the enemy and use them to "educate" and stir up a second immune response, known as "adaptive" immunity.

Until now, laboratory dish experiments hadn't revealed that the instantaneous or "innate" immune reaction--discovered less than 10 years ago--is mounted by two differently-specialized cells. It had been thought that the initially responding cells were uniformly macrophages, equipped for the two roles. The innate response swings into action when invading microbes are detected by molecules called Toll-like receptors (TLRs) that stick out of the cell's outer membrane, serving as a trip-wire to raise the alarm. The TLRs spur the monocytes to differentiate into the two rapid response cell types.

Why this matters became strikingly clear when the scientists studied different forms of leprosy for the pr esence of the two cell types. (One of the types, the microbe-eating macrophages, is labeled DC-SIGN+, while the other, the antigen-presenting dendritic cells, are termed CD1b+). In people who have the form of leprosy known as tuberculoid, or T-lep, the body has made a strong immune response and the infection stays localized to the skin. In patients with lepromatous leprosy, or L-lep, the bacteria have overwhelmed the immune defenses and can spread along nerves throughout the body and may cause blindness.

The scientists found DC-SIGN+ macrophages in both types of leprosy infections. The CD1b+ cells were present only in the milder form, indicating a successful battle against the leprosy bacterium. They were missing, however, in the more severe leprosy infections, meaning that the monocytes hadn't succeeded in producing those key anti-bacterial fighters.

"The logic here is that because their monocytes are unable to produce the [CD1b+] cells that can mobilize T-cells, these people don't respond well and become much sicker," commented Bloom. "This research gives us insights about how the body develops protective immunity against bugs that invade our cells--or fails to. Now we know the players, and we would love to look at them in other diseases such as tuberculosis in the lungs and juvenile diabetes."

Harvard School of Public Health is dedicated to advancing the public's health through learning, discovery, and communication. More than 300 faculty members are engaged in teaching and training the 900-plus student body in a broad spectrum of disciplines crucial to the health and well being of individuals and populations around the world. Programs and projects range from the molecular biology of AIDS vaccines to the epidemiology of cancer; from risk analysis to violence prevention; from maternal and children's health to quality of care measurement; from health care management to international health and human rights.


Source:Harvard School of Public Health

Related biology news :

1. Leprosy genome tells story of human migrations, French researchers report in Science
2. International Team Determines Geographic Origin of Leprosy
3. W.M. Keck Foundation funds study of friendly microbes
4. Yellowstone microbes fueled by hydrogen, according to U. of Colorado study
5. Harnessing microbes, one by one, to build a better nanoworld
6. Could microbes solve Russias chemical weapons conundrum?
7. Proteomics brings researchers closer to understanding microbes that produce acid mine drainage
8. Freeze-dried mats of microbes awaken in Antarctic streambed
9. Understanding the oceans microbes is key to the Earths future
10. Wisconsin scientists discover a master key to microbes pathogenic lifestyles
11. New method for identifying microbes
Post Your Comments:

(Date:11/16/2015)... SAN JOSE, Calif. , Nov 16, 2015 ... leading developer of human interface solutions, today announced ... new Synaptics TouchView ™ touch controller and ... the architectural revolution of smartphones. These new TDDI ... and include TD4100 (HD resolution), TD4302 (WQHD resolution), ...
(Date:11/10/2015)... 2015  In this report, the biomarkers ... product, type, application, disease indication, and geography. ... are consumables, services, software. The type segments ... efficacy biomarkers, and validation biomarkers. The applications ... development, drug discovery and development, personalized medicine, ...
(Date:11/2/2015)... 2015  SRI International has been awarded a contract ... services to the National Cancer Institute (NCI) PREVENT Cancer ... expertise, modern testing and support facilities, and analytical instrumentation ... toxicology studies to evaluate potential cancer prevention drugs. ... Cancer Drug Development Program is an NCI-supported pipeline to ...
Breaking Biology News(10 mins):
(Date:11/30/2015)... MAGDEBURG, Germany , November 30, 2015 /PRNewswire/ ... in Vienna, Austria to be held ... NeuroRehabilitation (ECNR) in Vienna, Austria ... a wholly owned subsidiary of Vycor Medical, Inc. ("Vycor") (OTCQB: ... Internet-delivered NovaVision Therapy Suite at the 3rd European Congress ...
(Date:11/30/2015)... ... November 30, 2015 , ... ... MarkLogic, the Enterprise NoSQL database platform provider, creating a seamless approach to ... Content Intelligence capabilities provide a robust set of semantic tools which create ...
(Date:11/28/2015)... ... November 28, 2015 , ... • Jeon Jin Bio Corp, a ... rodent control solutions , Bird Free, an ... across all sensory modalities including visual, smell, taste and touch, enabling safe, effective avian ...
(Date:11/27/2015)... (PRWEB) , ... November 27, 2015 , ... ... Program that includes over 2,000 technical presentations offered in symposia, oral sessions, ... and applied spectroscopy, covers a wide range of applications such as, but not ...
Breaking Biology Technology: