Welcome to the Keller lab at the Department of Pathobiology, Ontario Veterinary College. Adaptive immunity has evolved to recognize an almost infinite number of antigens. Antigen recognition is mediated through highly variable antigen receptors (ARs) on lymphocytes. The entirety of an individual’s AR specificities, the AR repertoire, is shaped by genetic and environmental factors and is a pivotal determinant of health and disease. We are interested in understanding the composition and dynamics of AR repertoires under normal and pathologic conditions. We leverage AR repertoire diversity to diagnose lymphoproliferative diseases.