Nicholas Chiorazzi, MD from The Feinstein Institute for Medical Research, Manhasset, NY discusses how cell surface markers change over time and how they can be utilized to understand more about the tissue. Researchers cannot very often get samples from solid they can get bone marrow samples on occasion and rarely, lymph node samples. Therefore, it is required to figure out markers on the surface of cells in the blood that represent cells that have recently left the solid tissue, for instance the bone marrow, lymph node, or the spleen. Dr Chiorazzi mentions how experts have been able to define several surface markers that are highly expressed on cells that have just divided (the newly born cells that have come out of the tissue). Furthermore, those particular markers actually change over time and by examining these changes, researchers can identify cells at those times and hopefully will be looking at cells that are representative of what is in the tissue. Recorded at the 2016 International Workshop of the German CLL Study Group (GCLLSG) in Cologne, Germany.