Ana-Maria Lennon-Duménil

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To initiate adaptative cytotoxic immune responses, proteolytic peptides derived from phagocytosed antigens are presented by dendritic cells (DCs) to CD8+ T lymphocytes through a process called antigen "crosspresentation." The partial degradation of antigens mediated by lysosomal proteases in an acidic environment must be tightly controlled to prevent(More)
Antigen (Ag) capture and presentation onto major histocompatibility complex (MHC) class II molecules by B lymphocytes is mediated by their surface Ag receptor (B cell receptor [BCR]). Therefore, the transport of vesicles that carry MHC class II and BCR-Ag complexes must be coordinated for them to converge for processing. In this study, we identify the(More)
Dendritic cells (DCs) sample peripheral tissues of the body in search of antigens to present to T cells. This requires two processes, antigen processing and cell motility, originally thought to occur independently. We found that the major histocompatibility complex II-associated invariant chain (Ii or CD74), a known regulator of antigen processing,(More)
During trafficking through tissues, T cells fine-tune their motility to balance the extent and duration of cell-surface contacts versus the need to traverse an entire organ. Here we show that in vivo, myosin IIA-deficient T cells had a triad of defects, including overadherence to high-endothelial venules, less interstitial migration and inefficient(More)
Here, we describe a new approach designed to monitor the proteolytic activity of maturing phagosomes in live antigen-presenting cells. We find that an ingested particle sequentially encounters distinct protease activities during phagosomal maturation. Incorporation of active proteases into the phagosome of the macrophage cell line J774 indicates that(More)
Supplemental Information Supplemental Information including experimental procedures, a figure and a table can be found with this article online at Acknowledgments We thank The Smithsonian Tropical Research Institute for providing facilities in Gamboa that allowed us to collect ant colonies and conduct the behavioural assays, Luke Holman and two anonymous(More)
Before a class II molecule can be loaded with antigenic material and reach the surface to engage CD4+ T cells, its chaperone, the class II-associated invariant chain (Ii), is degraded in a stepwise fashion by proteases in endocytic compartments. We have dissected the role of cathepsin S (CatS) in the trafficking and maturation of class II molecules by(More)
The immune synapse (IS) forms as dendritic cells (DCs) and T cells interact in lymph nodes during initiation of adaptive immunity. Factors that contribute to the formation and maintenance of IS stability and function have been mostly studied in T cells, whereas little is known about events occurring during synapse formation in DCs. Here, we show that DCs(More)
Secretion of proteases is critical for degradation of the extracellular matrix during an inflammatory response. Cathepsin (Cat) S and L are the major elastinolytic cysteine proteases in mouse macrophages. A 65 amino acid segment of the p41 splice variant (p41(65aa)) of major histocompatibility complex class II-associated invariant chain (Ii) binds to the(More)
Cell movement has essential functions in development, immunity, and cancer. Various cell migration patterns have been reported, but no general rule has emerged so far. Here, we show on the basis of experimental data in vitro and in vivo that cell persistence, which quantifies the straightness of trajectories, is robustly coupled to cell migration speed. We(More)