New Fluorescent Biosensor Reveals Antigen Transfer between Dendritic Cells

Published on April 25, 2012 at 4:19 AM

By Andy Choi

Researchers at Carnegie Mellon University have developed a new fluorescent biosensor that has helped them find out the mechanism for amplification of the immune system.

Dendritic cells, which are immune cells, are utilized by cancer vaccines for amplifying the immune system. The fluorescent sensor has helped the researchers to view the antigen transferring process that takes place between the immune cells in the immune system. These cells search and capture viruses, allergens and bacteria. These foreign bodies are totally covered and broken down into antigens. These antigens are then placed on the cell’s surface, which instruct other dendritic cells to search for foreign micro-organisms.

In order to increase the activation of other immune cells, dendritic cells can share the antigens. The mechanism by which the antigens on one dendritic cell moved to another dendritic cell was not known till now. At the Carnegie Mellon's Molecular and Biosensor Imaging Center, scientists developed a new pH-biosensor that consists of a fluorogen activating peptide (FAP) and a fluorogen dye. The FAP is expressed in a cell genetically and then tagged on to a specific protein. Based on the level of pH, the fluorogen glows with a green or red color.

The researchers tagged a FAP on a surrogate antigen on top of a dendritic cell surface. The addition of the dye made the FAP antigen to glow with a green color. This indicates a neutral pH. When the FAP antigen moved to another dendritic cell, it glowed with a red color, which indicates an acidic pathway. This phenomenon reveals that an active endocytic process makes the antigen to pass between cells.

This novel technology can lead to the development of targetable environmental sensors. The new approach may be used to measure ion fluctuations that occur in living cells.

This study has been published in Angewandte Chemie.