The Modlin laboratory is interested in identifying novel mechanisms by which the innate and adaptive immune system combat microbial pathogens. Previous studies from the laboratory have provided new paradigms for human innate immune responses including the first evidence that Toll-like receptors recognize microbial lipoproteins and can activate macrophages to kill intracellular pathogens. We have also shown vitamin D is required for generating antimicrobial peptides to kill intracellular pathogens and leading to killing of the mycobacteria for the first time by human cells in vitro. Recently, the Modlin laboratory revealed the complex immunological microenvironment of human leprosy granuloma via detailed spatial and temporal model of interactions among different cellular subsets, cytokine patterns, and antimicrobial pathways. Current studies in the laboratory focus on integrating immunologic studies with single cell transcriptomic data to probe at the cellular and mechanistic network that contribute to disease pathogenesis of acne, leprosy, and pulmonary tuberculosis.