Important note: Information in this article was accurate in 2002. The state of the art may have changed since the publication date.
|
|
TB & Outbreaks Week (12.17.02) - Friday, December 20, 2002
Michael Greer
"Inhaled particulates and microbes are continually cleared by a complex array of lung innate immune determinants, including alveolar macrophages (AMs)," explained Alison A. Beharka and colleagues at the University of Iowa and the Veterans Affairs Medical Center in Iowa City, the University of Colorado Health Sciences Center in Denver, and the University of Cincinnati. "AMs are unique cells with an enhanced capacity for phagocytosis that is due, in part, to increased activity of the macrophage mannose receptor (MR)." Surfactant protein A increases macrophage MR activity, which can enhance or, in some cases, degrade immune responses to infection, Beharka and coauthors found.
SP-A, a key component of lung surfactant, is known to augment macrophages' ability to kill infected cells through phagocytosis, the investigators said. Their study shows that SP-A selectively upregulates MR on human monocyte-derived macrophages. Study data showed that SP-A upregulation occurred quickly, even in the absence of new protein synthesis, suggesting the extra MR was drawn from intracellular sources.
However, the siphoning of intracellular MR triggered by SP-A could impair immune defenses against intracellular microbes, the authors warned. Their full report, "Pulmonary Surfactant Protein A Up-Regulates Activity of the Mannose Receptor, a Pattern Recognition Receptor Expressed on Human Macrophages" was published in the Journal of Immunology (2002;169(7):3565- 3573).
"SP-A upregulation of MR activity provides a mechanism for enhanced phagocytosis of microbes by AMs, thereby enhancing lung and host defense against extracellular pathogens or, paradoxically, enhancing the potential for intracellular pathogens to enter their intracellular niches," Beharka and colleagues concluded.
021220
AD022471
Copyright © 2002 - Information, Inc., Bethesda, MD. The CDC National Center for HIV, STD and TB Prevention provides the following information as a public service only. Providing synopses of key scientific articles and lay media reports on HIV/AIDS, other sexually transmitted diseases and tuberculosis does not constitute CDC endorsement. This daily update also includes information from CDC and other government agencies, such as background on Morbidity and Mortality Weekly Report (MMWR) articles, fact sheets, press releases and announcements. Reproduction of this text is encouraged; however, copies may not be sold, and the CDC HIV/STD/TB Prevention News Update should be cited as the source of the information. Contact the sources of the articles abstracted below for full texts of the articles.
AEGiS is a 501(c)3, not-for-profit, tax-exempt, educational corporation. AEGiS is made possible through unrestricted funding from Boehringer Ingelheim, Bridgestone/Firestone Charitable Trust, Elton John AIDS Foundation, the National Library of Medicine, AIDS Walk of Orange County, and donations from users like you.
Always watch for outdated information. This article first appeared in 2002. This material is designed to support, not replace, the relationship that exists between you and your doctor.AEGiS presents published material, reprinted with permission and neither endorses nor opposes any material. All information contained on this website, including information relating to health conditions, products, and treatments, is for informational purposes only. It is often presented in summary or aggregate form. It is not meant to be a substitute for the advice provided by your own physician or other medical professionals. Always discuss treatment options with a doctor who specializes in treating HIV.
Copyright ©1980, 2002. AEGiS. All materials appearing on AEGiS are protected by copyright as a collective work or compilation under U.S. copyright and other laws and are the property of AEGiS, or the party credited as the provider of the content.
.