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Resting memory CD8+ T cells are hyperreactive to antigenic challenge in vitro.

Pihlgren M, Dubois PM, Tomkowiak M, Sjögren T, Marvel J - J. Exp. Med. (1996)

Bottom Line: These cells differ in terms of cell cycle status, surface phenotype, and/or effector function.The activation thresholds of naive and primed CD8+ T cells were compared in vitro.We found that CD8+ T cells from primed mice are activated by peptide concentrations 10-50-fold lower than naive mice.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Biologie Moleculaire et Cellulaire de Ecole Normale Superieure Lyon centre National de la Recherche Scientifique Unité Mixte de Recherche, France.

ABSTRACT
The characteristics of CD8+ T cells responsible for memory responses are still largely unknown. Particularly, it has not been determined whether different activation thresholds distinguish naive from memory CD8+ T cell populations. In most experimental systems, heterogeneous populations of primed CD8+ T cells can be identified in vivo after immunization. These cells differ in terms of cell cycle status, surface phenotype, and/or effector function. This heterogeneity has made it difficult to assess the activation threshold and the relative role of these subpopulations in memory responses. In this study we have used F5 T cell receptor transgenic mice to generate a homogeneous population of primed CD8+ T cells. In the F5 transgenic mice, peptide injection in vivo leads to activation of most peripheral CD8+ T cells. In vivo BrdU labeling has been used to follow primed T cells over time periods spanning several weeks after peptide immunization. Our results show that the majority of primed CD8+ T cells generated in this system are not cycling and express increased levels of CD44 and Ly6C. These cells remain responsive to secondary peptide challenge in vivo as evidenced by short term upregulation of activation markers such as CD69 and CD44. The activation thresholds of naive and primed CD8+ T cells were compared in vitro. We found that CD8+ T cells from primed mice are activated by peptide concentrations 10-50-fold lower than naive mice. In addition, the kinetics of interleukin 2R alpha chain upregulation by primed CD8+ T cells differ from naive CD8+ T cells. These primed hyperresponsive CD8+ T cells might play an important role in the memory response.

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In vivo BrdU incorporation by transgenic CD8+ T cells after  peptide stimulation. Thymectomized and euthymic mice were either immunized with 50 nmol peptide on day 0 (Activated) or received only PBS  (Naive). BrdU was given in the drinking water for 4 d starting 1 d before  peptide injection. 3 d after peptide challenge, spleen cells were double  stained for BrdU and CD8 or triple stained for BrdU, CD8, and CD44.  Results for one representative mouse are shown. The percentage of  BrdU+ and BrdU− CD8+ T cells is given in the first column. The total  number (×106) of BrdU+CD8+ cells is given in brackets. The expression  of CD44 by BrdU labeled cells is shown for gated CD8+ T cells. Results  for one representative mouse out of two naive or four primed mice are  shown.
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Figure 1: In vivo BrdU incorporation by transgenic CD8+ T cells after peptide stimulation. Thymectomized and euthymic mice were either immunized with 50 nmol peptide on day 0 (Activated) or received only PBS (Naive). BrdU was given in the drinking water for 4 d starting 1 d before peptide injection. 3 d after peptide challenge, spleen cells were double stained for BrdU and CD8 or triple stained for BrdU, CD8, and CD44. Results for one representative mouse are shown. The percentage of BrdU+ and BrdU− CD8+ T cells is given in the first column. The total number (×106) of BrdU+CD8+ cells is given in brackets. The expression of CD44 by BrdU labeled cells is shown for gated CD8+ T cells. Results for one representative mouse out of two naive or four primed mice are shown.

Mentions: To determine the proportion of CD8+ T lymphocytes proliferating in a primary response to peptide, we used in vivo BrdU labeling. Results presented in Fig. 1 show that the majority of F5 spleen CD8+ T cells incorporated BrdU in their DNA 3 d after peptide injection. The same CD8+BrdU+ T cell population also expressed high levels of CD44. In control mice, only a small percentage of spleen CD8+ T cells incorporated BrdU and expressed CD44, consistent with the view that naive cells are CD44− noncycling cells (20). Similar results were obtained in thymectomized and nonthymectomized animals, indicating that the BrdU is incorporated in peripheral T cells and not in immature thymocytes (Fig. 1). Together these data indicate that the majority of the peripheral T cell pool can be activated and enters the cell cycle in response to peptide stimulation in vivo.


Resting memory CD8+ T cells are hyperreactive to antigenic challenge in vitro.

Pihlgren M, Dubois PM, Tomkowiak M, Sjögren T, Marvel J - J. Exp. Med. (1996)

In vivo BrdU incorporation by transgenic CD8+ T cells after  peptide stimulation. Thymectomized and euthymic mice were either immunized with 50 nmol peptide on day 0 (Activated) or received only PBS  (Naive). BrdU was given in the drinking water for 4 d starting 1 d before  peptide injection. 3 d after peptide challenge, spleen cells were double  stained for BrdU and CD8 or triple stained for BrdU, CD8, and CD44.  Results for one representative mouse are shown. The percentage of  BrdU+ and BrdU− CD8+ T cells is given in the first column. The total  number (×106) of BrdU+CD8+ cells is given in brackets. The expression  of CD44 by BrdU labeled cells is shown for gated CD8+ T cells. Results  for one representative mouse out of two naive or four primed mice are  shown.
© Copyright Policy
Related In: Results  -  Collection

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Figure 1: In vivo BrdU incorporation by transgenic CD8+ T cells after peptide stimulation. Thymectomized and euthymic mice were either immunized with 50 nmol peptide on day 0 (Activated) or received only PBS (Naive). BrdU was given in the drinking water for 4 d starting 1 d before peptide injection. 3 d after peptide challenge, spleen cells were double stained for BrdU and CD8 or triple stained for BrdU, CD8, and CD44. Results for one representative mouse are shown. The percentage of BrdU+ and BrdU− CD8+ T cells is given in the first column. The total number (×106) of BrdU+CD8+ cells is given in brackets. The expression of CD44 by BrdU labeled cells is shown for gated CD8+ T cells. Results for one representative mouse out of two naive or four primed mice are shown.
Mentions: To determine the proportion of CD8+ T lymphocytes proliferating in a primary response to peptide, we used in vivo BrdU labeling. Results presented in Fig. 1 show that the majority of F5 spleen CD8+ T cells incorporated BrdU in their DNA 3 d after peptide injection. The same CD8+BrdU+ T cell population also expressed high levels of CD44. In control mice, only a small percentage of spleen CD8+ T cells incorporated BrdU and expressed CD44, consistent with the view that naive cells are CD44− noncycling cells (20). Similar results were obtained in thymectomized and nonthymectomized animals, indicating that the BrdU is incorporated in peripheral T cells and not in immature thymocytes (Fig. 1). Together these data indicate that the majority of the peripheral T cell pool can be activated and enters the cell cycle in response to peptide stimulation in vivo.

Bottom Line: These cells differ in terms of cell cycle status, surface phenotype, and/or effector function.The activation thresholds of naive and primed CD8+ T cells were compared in vitro.We found that CD8+ T cells from primed mice are activated by peptide concentrations 10-50-fold lower than naive mice.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Biologie Moleculaire et Cellulaire de Ecole Normale Superieure Lyon centre National de la Recherche Scientifique Unité Mixte de Recherche, France.

ABSTRACT
The characteristics of CD8+ T cells responsible for memory responses are still largely unknown. Particularly, it has not been determined whether different activation thresholds distinguish naive from memory CD8+ T cell populations. In most experimental systems, heterogeneous populations of primed CD8+ T cells can be identified in vivo after immunization. These cells differ in terms of cell cycle status, surface phenotype, and/or effector function. This heterogeneity has made it difficult to assess the activation threshold and the relative role of these subpopulations in memory responses. In this study we have used F5 T cell receptor transgenic mice to generate a homogeneous population of primed CD8+ T cells. In the F5 transgenic mice, peptide injection in vivo leads to activation of most peripheral CD8+ T cells. In vivo BrdU labeling has been used to follow primed T cells over time periods spanning several weeks after peptide immunization. Our results show that the majority of primed CD8+ T cells generated in this system are not cycling and express increased levels of CD44 and Ly6C. These cells remain responsive to secondary peptide challenge in vivo as evidenced by short term upregulation of activation markers such as CD69 and CD44. The activation thresholds of naive and primed CD8+ T cells were compared in vitro. We found that CD8+ T cells from primed mice are activated by peptide concentrations 10-50-fold lower than naive mice. In addition, the kinetics of interleukin 2R alpha chain upregulation by primed CD8+ T cells differ from naive CD8+ T cells. These primed hyperresponsive CD8+ T cells might play an important role in the memory response.

Show MeSH