492 Phagocyte heterogeneity and T cell dependence of cellular host defense mechanisms in tuberculosis

Abstract

OBJECTIVES/GOALS: Phagocytes, diverse cells that ingest material, are the primary cell type infected by Mycobacterium tuberculosis (Mtb) and the executors of protective mechanisms. T cells play a critical role by helping phagocytes control the infection. Understanding the precise T cell-dependent mechanisms by which phagocytic cell types contain Mtb is critical. METHODS/STUDY POPULATION: To determine the impact T cells have on different phagocyte cell populations’ host defense mechanisms, groups of wild–type and T cell deficient TCRa-/- mice were infected with an Mtb strain expressing fluorescent mScarlet protein. At four weeks post-infection, a time when T cell help contributes to control of Mtb, lungs were homogenized and cells sorted based on detection of mScarlet, indicating Mtb-infected cells. Cell suspensions from each mouse background were underwent single-cell RNA sequencing analysis to reveal the heterogenous cellular transcriptional response of different phagocyte populations. RESULTS/ANTICIPATED RESULTS: We found that Mtb-infected phagocytes from wild-type and TCRa-/- mouse lungs contain the same dominant cell phenotypic clusters, but these have different patterns of gene expression. Without T cells, phagocytes are prone to a more inflammatory phenotype. DISCUSSION/SIGNIFICANCE: This will translate fundamental biological data to test the hypothesis that Mtb encounters different environmental stresses exerted by different phagocytic cell types. This work could reveal host intracellular niches that enable bacterial persistence and elucidate new pathways that could be targeted for traditional antibiotic therapies for TB.