NEW YORK, Oct. 25—A new study using DNA chips to probe the activity of the immune system indicates that dendritic cells discriminate between different kinds of invading pathogens, and are involved in directing tailored immune responses. The study, to appear in the October 26 issue of Science , was led by immunologist Nir Hacohen at the Whitehead Institute for Biomedical Research at MIT.
Hacohen’s team used Affymetrix’s GeneChips to monitor the genetic activity of dendritic cells during exposure to three different types of infectious agents: an influenza virus, the E. coli bacteria, and the fungus Candida albicans . The researchers determined that each pathogen activated a unique set of genes, which in turn generated different elements of the immune response. For example, the bacteria activated genes that attract neutrophils, but the virus did not.
Dendritic cells are part of the early response division of the immune system, activating other arms of the immune system in response to infectious agents such as viruses and bacteria. Their function is not as well understood as other parts of the immune response. Hacohen said the microarray chips provided “a way of getting a snapshot of the state of dendritic cells.” He said, “By looking at many genes you get a rapid assessment of what the dendritic cell is capable of doing. There’s no other way to get such a comprehensive snapshot. You could look at a gene here, or a gene there, but this is the only way to get the global view.”
According to Hacohen, the team has identified a large set of genes that are activated in the presence of pathogens, and the next step is to determine what function theses genes have in dendritic cells and how they are turned on and off. Those insights may then be applied to design better therapies.