“Kiss-and-run” approach helps researchers observe interaction between dendritic cells and T cells.
The normal biological processes needed for living beings to develop, grow, and function involve interactions between a diversity of cell types. Targeting these cellular interactions can enhance current cell-based immunotherapy and regenerative medicine, as well as provide the basis for new ones. Studying the mechanisms of these interactions is necessary in order to understand the means by which they affect cell signaling, immunity, growth and development, and more.
Currently, in vivo monitoring of intercellular interactions can be accomplished using intravital microscopy (imaging in live animals). However, it has not been possible to obtain functional information regarding the cells that effectively interact, the receptors and ligands involved, or to isolate the specific interacting cells for further analysis. Such information would significantly enhance medical research efforts to develop therapies that directly target cell-cell interactions, ultimately improving patient outcomes for a number of conditions that could benefit from immunotherapeutic approaches.
Researchers from the Laboratory of Lymphocyte Dynamics, The Rockefeller University, developed an approach using a bacterial enzyme capable of modifying surface proteins to address the mechanistic questions regarding cell-cell interactions. This involved using bacterial sortase labeling of immune cells in living mice to identify receptor-ligand interactions between dendritic and T cells. They injected the feet of mice with primed dendritic cells, which then traveled to the closest lymph node to interact with T cells there. The lymph nodes were later analyzed using flow cytometry.
The researchers call the approach to detect what are termed “kiss-and-run” interactions (brief cell-cell encounters) between immune cells, Labeling Immune Partnerships by SorTagging Intercellular Contacts (LIPSTIC). With the LIPSTIC technique, the researchers were able to observe interaction between labeled dendritic cells (stained red) and T cells (stained green) because these cells tagged each other with a white fluorescent stain when they came in contact. Therefore, it was possible to identify and even count the interacting cells. This functional analysis of cell-cell interactions was not previously possible, and there is a high potential of clinical translation of the information gathered using LIPSTIC.