Arnaout’s research on the biology and structure of integrins has led to scientific observations that span the entire spectrum from gene discovery to 3-dimensional protein structure to clinical translation.He described an inherited deficiency in leukocyte adhesion in a lead article in the New England Journal of Medicine; defined the biochemical and molecular basis of this disease, which he traced to a deficiency in a family of leukocyte receptors, now known as leukocyte integrins and elucidated the role of these cell adhesion molecules in the immune system.