Limits...
Visualizing early splenic memory CD8+ T cells reactivation against intracellular bacteria in the mouse.

Bajénoff M, Narni-Mancinelli E, Brau F, Lauvau G - PLoS ONE (2010)

Bottom Line: Memory CD8(+) T cells are endowed with enhanced antimicrobial effector functions that perfectly tail them to rapidly eradicate invading pathogens.Within these clusters that only last few hours, memory CD8(+) T produce inflammatory cytokines such as IFN-gamma and CCL3 nearby infected myeloid cells known to be crucial for L.m killing.Altogether, we describe how memory CD8(+) T cells trafficking properties and the splenic micro-anatomy conjugate to create a spatio-temporal window during which memory CD8(+) T cells provide a local response by secreting effector molecules around infected cells.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale Unité 924, Groupe Avenir, Valbonne, France. bajenoff@ciml.univ-mrs.fr

ABSTRACT
Memory CD8(+) T cells represent an important effector arm of the immune response in maintaining long-lived protective immunity against viruses and some intracellular bacteria such as Listeria monocytogenes (L.m). Memory CD8(+) T cells are endowed with enhanced antimicrobial effector functions that perfectly tail them to rapidly eradicate invading pathogens. It is largely accepted that these functions are sufficient to explain how memory CD8(+) T cells can mediate rapid protection. However, it is important to point out that such improved functional features would be useless if memory cells were unable to rapidly find the pathogen loaded/infected cells within the infected organ. Growing evidences suggest that the anatomy of secondary lymphoid organs (SLOs) fosters the cellular interactions required to initiate naive adaptive immune responses. However, very little is known on how the SLOs structures regulate memory immune responses. Using Listeria monocytogenes (L.m) as a murine infection model and imaging techniques, we have investigated if and how the architecture of the spleen plays a role in the reactivation of memory CD8(+) T cells and the subsequent control of L.m growth. We observed that in the mouse, memory CD8(+) T cells start to control L.m burden 6 hours after the challenge infection. At this very early time point, L.m-specific and non-specific memory CD8(+) T cells localize in the splenic red pulp and form clusters around L.m infected cells while naïve CD8(+) T cells remain in the white pulp. Within these clusters that only last few hours, memory CD8(+) T produce inflammatory cytokines such as IFN-gamma and CCL3 nearby infected myeloid cells known to be crucial for L.m killing. Altogether, we describe how memory CD8(+) T cells trafficking properties and the splenic micro-anatomy conjugate to create a spatio-temporal window during which memory CD8(+) T cells provide a local response by secreting effector molecules around infected cells.

Show MeSH

Related in: MedlinePlus

L.m-specific memory CD8+ T cells transiently form clusters in the Red Pulp of secondary infected animals.(A, B) 200 naïve GFP+ OT-I cells were transferred in C57BL/6 mice that were injected i.v. the following day with 0.1×LD50 Wt L.m-OVA. One month later, mice were injected i.v. with PBS or 10×LD50 Wt L.m-OVA. Spleens were harvested 3, 6, 12 and 24 hours later, sectioned, stained for B220, CD3, collagen IV expression and analyzed by confocal microscopy. Arrowheads indicate clusters of GFP+ OT-I memory cells 6 hours post re-infection. (B) The surfaces of WP and RP zones were delineated based on collagen IV expression and summed up. The densities of memory GFP+ OT-I cells per mm2 of each region were calculated and displayed. Data are representative of 3 independent experiments.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2902518&req=5

pone-0011524-g005: L.m-specific memory CD8+ T cells transiently form clusters in the Red Pulp of secondary infected animals.(A, B) 200 naïve GFP+ OT-I cells were transferred in C57BL/6 mice that were injected i.v. the following day with 0.1×LD50 Wt L.m-OVA. One month later, mice were injected i.v. with PBS or 10×LD50 Wt L.m-OVA. Spleens were harvested 3, 6, 12 and 24 hours later, sectioned, stained for B220, CD3, collagen IV expression and analyzed by confocal microscopy. Arrowheads indicate clusters of GFP+ OT-I memory cells 6 hours post re-infection. (B) The surfaces of WP and RP zones were delineated based on collagen IV expression and summed up. The densities of memory GFP+ OT-I cells per mm2 of each region were calculated and displayed. Data are representative of 3 independent experiments.

Mentions: Because memory OT-I cells were predominantly found in the RP and in the bloodstream of infected mice, we reasoned that the early (6 hours) control of L.m growth should occur in the RP, before infected cells have reached the WP. To investigate these early events, 200 GFP+ OT-I cells were adoptively transferred in recipient mice that were injected 1 day later with 0.1×LD50 Wt L.m-OVA. After 30 days, animals were challenged with 10×LD50 Wt L.m-OVA. Spleens were harvested 3, 6, 12 and 24 hours later, sectioned and stained for B220, CD3, and collagen IV expression (Figure 5A). At 3 hours, memory OT-I cells were present in the WP and the RP of re-infected animals in the same proportions than untreated animals. Most interestingly, at 6 hours, we observed the formation of OT-I clusters in the RP of secondary infected animals (arrowheads). These clusters were transient since they were largely crumbled after 12 hours and completely dissolved at 24 hours, when OT-I cells had massively relocated to the T cell zone (Figure 5A). Quantification of the density of OT-I cells per mm2 of RP and WP confirmed this impression, indicating that a transient clustering of L.m-specific memory CD8+ T cells in the RP precedes their relocation to the WP (Figure 5B).


Visualizing early splenic memory CD8+ T cells reactivation against intracellular bacteria in the mouse.

Bajénoff M, Narni-Mancinelli E, Brau F, Lauvau G - PLoS ONE (2010)

L.m-specific memory CD8+ T cells transiently form clusters in the Red Pulp of secondary infected animals.(A, B) 200 naïve GFP+ OT-I cells were transferred in C57BL/6 mice that were injected i.v. the following day with 0.1×LD50 Wt L.m-OVA. One month later, mice were injected i.v. with PBS or 10×LD50 Wt L.m-OVA. Spleens were harvested 3, 6, 12 and 24 hours later, sectioned, stained for B220, CD3, collagen IV expression and analyzed by confocal microscopy. Arrowheads indicate clusters of GFP+ OT-I memory cells 6 hours post re-infection. (B) The surfaces of WP and RP zones were delineated based on collagen IV expression and summed up. The densities of memory GFP+ OT-I cells per mm2 of each region were calculated and displayed. Data are representative of 3 independent experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2902518&req=5

pone-0011524-g005: L.m-specific memory CD8+ T cells transiently form clusters in the Red Pulp of secondary infected animals.(A, B) 200 naïve GFP+ OT-I cells were transferred in C57BL/6 mice that were injected i.v. the following day with 0.1×LD50 Wt L.m-OVA. One month later, mice were injected i.v. with PBS or 10×LD50 Wt L.m-OVA. Spleens were harvested 3, 6, 12 and 24 hours later, sectioned, stained for B220, CD3, collagen IV expression and analyzed by confocal microscopy. Arrowheads indicate clusters of GFP+ OT-I memory cells 6 hours post re-infection. (B) The surfaces of WP and RP zones were delineated based on collagen IV expression and summed up. The densities of memory GFP+ OT-I cells per mm2 of each region were calculated and displayed. Data are representative of 3 independent experiments.
Mentions: Because memory OT-I cells were predominantly found in the RP and in the bloodstream of infected mice, we reasoned that the early (6 hours) control of L.m growth should occur in the RP, before infected cells have reached the WP. To investigate these early events, 200 GFP+ OT-I cells were adoptively transferred in recipient mice that were injected 1 day later with 0.1×LD50 Wt L.m-OVA. After 30 days, animals were challenged with 10×LD50 Wt L.m-OVA. Spleens were harvested 3, 6, 12 and 24 hours later, sectioned and stained for B220, CD3, and collagen IV expression (Figure 5A). At 3 hours, memory OT-I cells were present in the WP and the RP of re-infected animals in the same proportions than untreated animals. Most interestingly, at 6 hours, we observed the formation of OT-I clusters in the RP of secondary infected animals (arrowheads). These clusters were transient since they were largely crumbled after 12 hours and completely dissolved at 24 hours, when OT-I cells had massively relocated to the T cell zone (Figure 5A). Quantification of the density of OT-I cells per mm2 of RP and WP confirmed this impression, indicating that a transient clustering of L.m-specific memory CD8+ T cells in the RP precedes their relocation to the WP (Figure 5B).

Bottom Line: Memory CD8(+) T cells are endowed with enhanced antimicrobial effector functions that perfectly tail them to rapidly eradicate invading pathogens.Within these clusters that only last few hours, memory CD8(+) T produce inflammatory cytokines such as IFN-gamma and CCL3 nearby infected myeloid cells known to be crucial for L.m killing.Altogether, we describe how memory CD8(+) T cells trafficking properties and the splenic micro-anatomy conjugate to create a spatio-temporal window during which memory CD8(+) T cells provide a local response by secreting effector molecules around infected cells.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale Unité 924, Groupe Avenir, Valbonne, France. bajenoff@ciml.univ-mrs.fr

ABSTRACT
Memory CD8(+) T cells represent an important effector arm of the immune response in maintaining long-lived protective immunity against viruses and some intracellular bacteria such as Listeria monocytogenes (L.m). Memory CD8(+) T cells are endowed with enhanced antimicrobial effector functions that perfectly tail them to rapidly eradicate invading pathogens. It is largely accepted that these functions are sufficient to explain how memory CD8(+) T cells can mediate rapid protection. However, it is important to point out that such improved functional features would be useless if memory cells were unable to rapidly find the pathogen loaded/infected cells within the infected organ. Growing evidences suggest that the anatomy of secondary lymphoid organs (SLOs) fosters the cellular interactions required to initiate naive adaptive immune responses. However, very little is known on how the SLOs structures regulate memory immune responses. Using Listeria monocytogenes (L.m) as a murine infection model and imaging techniques, we have investigated if and how the architecture of the spleen plays a role in the reactivation of memory CD8(+) T cells and the subsequent control of L.m growth. We observed that in the mouse, memory CD8(+) T cells start to control L.m burden 6 hours after the challenge infection. At this very early time point, L.m-specific and non-specific memory CD8(+) T cells localize in the splenic red pulp and form clusters around L.m infected cells while naïve CD8(+) T cells remain in the white pulp. Within these clusters that only last few hours, memory CD8(+) T produce inflammatory cytokines such as IFN-gamma and CCL3 nearby infected myeloid cells known to be crucial for L.m killing. Altogether, we describe how memory CD8(+) T cells trafficking properties and the splenic micro-anatomy conjugate to create a spatio-temporal window during which memory CD8(+) T cells provide a local response by secreting effector molecules around infected cells.

Show MeSH
Related in: MedlinePlus