Activating Receptors Triggers Immune Cell Change into Two Distinct Cell Populations

Newswise — FINDINGS: UCLA researchers discovered that activation of the body's immune system through specific receptors -- called Toll-like receptors -- on the surface of blood cells leads to their rapid cell change into two distinct immune system populations: macrophages and dendritic cells. Each of these cell types has a unique function. Like a general in the army, dendritic cells lead the immune system in activating other cells. Macrophages are the soldiers of the immune system, carrying out orders such as gobbling up invading bacteria.

Researchers also found that in the skin disease leprosy, the changing of cells into dendritic cells was deficient in the group of patients that are unable to control the infection. Researchers also identified that a molecule called DC-SIGN, known to bind to HIV and the bacteria that causes tuberculosis, was present on a specific group of macrophages.

IMPACT: The findings will be of broad interest to immunologists and infectious disease specialists because it identifies mechanisms through which the immune system controls both pathogen capture and the ensuing immune responses to infections. Importantly, this study also describes that cells expressing the molecule DC-SIGN, a receptor for HIV, are a subset of macrophages, providing a new direction for the study of HIV pathogenesis. Understanding the function of these cells may offer new insights into how the body defends against pathogen invasion.

AUTHORS: Dr. Stephan Krutzik, UCLA assistant adjunct professor of medicine, division of dermatology and Dr. Robert Modlin, UCLA professor of medicine and chief, division of dermatology, are available for interviews.

JOURNAL: The research appears on the May 8 online edition of the peer reviewed Nature Medicine.