title: Reciprocal polarization of T and B cells at the immunological synapse.
abstract: Cognate interactions between T and B lymphocytes lead to the formation of the immunological synapse (IS) where bidirectional activation signals are exchanged. Although the molecular architecture and the function of the IS have been studied extensively on the T cell side, little is known about events occurring during synapse formation in Ag-presenting B cells. We investigated the impact of BCR and TLR signaling on human B cell activation and on the T and B cell side of the IS. On the T cell side, we observed that T cells polarized toward both naive and previously activated B cells. Nevertheless, when T cells interacted with different B cells simultaneously, T cells selectively polarized their secretory machinery toward preactivated B cells. Furthermore, both naive and preactivated B cells reoriented their microtubule-organizing center toward the synaptic T cell during cognate interactions. This phenomenon was rapid and not dependent on T cell secretory activity. Interestingly, not only the microtubule-organizing center but also the Golgi apparatus and Lamp-3(+) and MHC class II(+) vesicles all repositioned beneath the IS, suggesting that the entire endocytic/exocytic B cell compartment was reoriented toward the T cell. Taken together, our results show that the B cell activation status fine-tunes T cell polarization responses and reveal the capacity of naive and activated B cells to polarize toward T cells during cognate interactions.
authors.affiliation: Centre de Physiopathologie de Toulouse Purpan, Section Dynamique Moléculaire des Interactions Lymphocytaires, INSERM U1043, F 31300 Toulouse, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Duchez
authors.forename: Magda
authors.initials: M
authors.lastname: Rodrigues
authors.forename: Florie
authors.initials: F
authors.lastname: Bertrand
authors.forename: Salvatore
authors.initials: S
authors.lastname: Valitutti
mesh_terms: D000818:Animals; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D002450:Cell Communication / Q000235:genetics / Q000276:immunology*; D016764:Cell Polarity / Q000235:genetics / Q000276:immunology*; D002478:Cells, Cultured; D002999:Clone Cells; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006801:Humans; D054992:Immunological Synapses / Q000235:genetics / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology / Q000276:immunology / Q000378:metabolism
chemical_list: D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte