T cell repertoire scanning is promoted by dynamic dendritic cell behavior and random T cell motility in the lymph node

Abstract

Dendritic cells (DCs) ingest antigens in peripheral tissues and migrate to lymph nodes where they present MHC class II-bound antigen to CD4 ؉ T cells. We used two-photon microscopy to image the single-cell dynamics of interactions between DCs and T cells within intact lymph nodes in the absence of relevant antigen. DCs were fluorescently labeled in vivo by cutaneous injection of alum adjuvant including carboxyfluorescein diacetate succinimidyl ester (CFSE). CFSE-positive DCs (CD11c ؉ , CD11b ؉ , and low-to-intermediate CD8 ؉ ) were observed in draining lymph nodes 24 -72 h later. Labeled DCs meandered slowly (2-3 m⅐min ؊1 ) in the T cell zone near B cell follicles but vigorously extended long agile dendrites. Encounters between T cells and DCs arose as T cells moved autonomously along random paths. Moreover, T cells did not accumulate around DCs, and their relative velocities approaching and departing DCs were equivalent, implying that T cells are not attracted toward DCs by chemotactic gradients but rather encounter them by chance. T cell͞DC contacts occurred primarily on dendrites at arm's length from the DC soma and typically lasted Ϸ3 min, enabling an individual DC to interact with up to 5,000 T cells per hour. We conclude that dynamic DC gesticulation and random T cell motility together enhance the stochastic scanning of the T cell repertoire, thereby enabling rapid initiation of the immune response.two-photon microscopy ͉ T lymphocyte

‘Survival gene’ Bcl-xl potentiates DNA-raised antitumor immunity

“…This is not unexpected, as several studies have shown that very few Ag-presenting DCs are necessary to induce potent immune responses. 42,43 It is likely that few 'prolonged' antigenbearing DCs can amplify Ag-specific T-cell responses (Figures 2 and 3) in this immunologic compartment. Taken together, these observations indicate that administration of CD11c-Bcl-xl DNA prolongs T-cell stimulation and improves the magnitude of TRP2-specific-CD8+ T-cell response induced by TRP2hsp70 DNA vaccine.…”

“…It was suggested that DCs have extreme efficacy in stimulating T cells in the lymph lodes. 43 A recent study showed that individual long-lasting DC-T-cell interactions result in priming, whereas brief contact may contribute to the induction of T-cell tolerance. 51 It is likely that prolonged antigen-bearing DC survival may increase the chance or stability of DC-T-cell interactions during the induction of T-cell priming.…”

3D and 4D imaging of immune cells in vitro and in vivo

“…The direct observation also allows to investigate cell-cell interactions that is especially important when analyzing the function of immune cells (Gunzer 2007). For example, the duration of contacts between T cells and APC (Bousso and Robey 2003;Castellino et al 2006;Gunzer et al 2000Gunzer et al , 2004Mempel et al 2004;Miller et al 2004a;Shakhar et al 2005), cytotoxic cells and their targets (Mempel et al 2006;Stinchcombe et al 2001) or B cells with antigen containing cells have been analyzed (Batista et al 2001;Fleire et al 2006). …”

“…Shortly after this, the Wrst papers investigating cell migration in explanted lymph nodes or thymic stromal reaggregate cultures (Bousso et al 2002) were published, followed by true intravital studies (Gunzer et al 2004;Mempel et al 2004). Meanwhile the number of reports using intravital 2PM for immunological questions has risen enormously, spanning from the cellular events of T cell activation (Miller et al 2004a), formation and function of germinal centers (Allen et al 2007b;Schwickert et al 2007) or function of regulatory T cells (Tadokoro et al 2006) to complex processes such as granuloma formation ) and the delivery of antigens (Carrasco and Batista. 2007;Qi et al 2006) or viruses to B cells (Junt et al 2007a).…”

T cell–antigen-presenting cell interactions visualized in vivo in a model of antigen-specific inflammation

“…More recently in vivo documentation of T cell and APC trafficking and interactions have been documented, especially through the use of two photon confocal microscopy [4,5,6,7,8,9]. The majority of these studies involve the lymph node or other lymphoid organ such as the bone marrow or thymus [10,11].…”