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Antigen is required for the activation of effector activities, whereas interleukin 2 Is required for the maintenance of memory in ovalbumin-specific, CD8+ cytotoxic T lymphocytes.

Ke Y, Ma H, Kapp JA - J. Exp. Med. (1998)

Bottom Line: Thus, the effector functions of these CTLs were rapidly induced by T cell receptor (TCR) occupancy.In the absence of OVA, the precursor frequency was identical in spleens of normal and beta2-microglobulin knockout recipients, but significantly less in IL-2 knockout mice.The decline of memory in the absence of IL-2 supports data from other investigators, suggesting that cell cycling is important to the maintenance of CD8+ T cell memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322, USA.

ABSTRACT
The mechanisms that maintain memory in T cells are not completely understood. We have investigated the role of antigen and interleukin (IL)-2 in the growth and maintenance of CD8+ T cells using a cytolytic T cell line specific for ovalbumin (OVA)257-264 presented by H-2Kb. This line does not secrete IL-4 or IL-2; hence, stimulation with the OVA-transfected EL4 line (E.G7-OVA) does not induce proliferation without addition of exogenous growth factors. Furthermore, this line can be maintained continuously by weekly addition of irradiated, splenic filler cells and IL-2, with or without E.G7-OVA. Although IL-2 induced proliferation of these cytotoxic T lymphocytes (CTLs), production of interferon gamma and tumor necrosis factor alpha required stimulation of the CTL with E. G7-OVA. The kinetics of lymphokine secretion after stimulation by E. G7-OVA were the same whether the CTL had been maintained with or without antigen (Ag). In addition, both CTL lines killed E.G7-OVA target cells within 4 h. Thus, the effector functions of these CTLs were rapidly induced by T cell receptor (TCR) occupancy. CTLs cultured with or without Ag also served as memory T cells when parked for 100 d in unirradiated, syngeneic recipients without OVA. In the absence of OVA, the precursor frequency was identical in spleens of normal and beta2-microglobulin knockout recipients, but significantly less in IL-2 knockout mice. The decline of memory in the absence of IL-2 supports data from other investigators, suggesting that cell cycling is important to the maintenance of CD8+ T cell memory. These data also suggest that stimulation of OVA-specific CTLs by lymphokines seems to be more important to maintaining memory than stimulation of TCRs by cross-reactive peptides complexed to class I molecules.

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Precursor frequency of donor CTLs in recipient spleen cells. OVA-CTLs (5  × 106) were adoptively transferred into unirradiated, syngeneic normal, β2m−/− or IL-2−/−  mice. After 5 wk, recipients  were killed and spleen cells from  several mice were pooled and titrated in 24 wells of 96-well  plates. Irradiated E.G7-OVA,  syngeneic filler cells, and Con A  supernatant were added to the  cultures. After incubation at 37°C for 1 wk, the wells were restimulated  as described above. After an additional week in culture, the cytolytic activity of the recovered cells was tested using 51Cr-labeled E.G7-OVA targets. The log of the percentage of negative wells was plotted on the ordinate and the number of spleen cells on the abscissa.
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Figure 8: Precursor frequency of donor CTLs in recipient spleen cells. OVA-CTLs (5 × 106) were adoptively transferred into unirradiated, syngeneic normal, β2m−/− or IL-2−/− mice. After 5 wk, recipients were killed and spleen cells from several mice were pooled and titrated in 24 wells of 96-well plates. Irradiated E.G7-OVA, syngeneic filler cells, and Con A supernatant were added to the cultures. After incubation at 37°C for 1 wk, the wells were restimulated as described above. After an additional week in culture, the cytolytic activity of the recovered cells was tested using 51Cr-labeled E.G7-OVA targets. The log of the percentage of negative wells was plotted on the ordinate and the number of spleen cells on the abscissa.

Mentions: The requirements for persistence of OVA-CTLs were examined next. To test whether memory was maintained by stimulation with cross-reactive peptides complexed to MHC class I, β2m knockout recipients were used. Because OVA-CTLs do not produce IL-2, the potential role of host IL-2 in long-term persistence memory could be addressed using IL-2 knockout mice. 5 wk after transfer, spleen cells from recipient mice were restimulated in vitro with E.G7-OVA, syngeneic filler cells, and IL-2. The frequencies of donor OVA-CTLs in the host spleen cells were then analyzed. As shown in Fig. 8, the frequency of donor OVA-CTLs in spleen cells from β2m−/− mice was in the same order of magnitude as in normal recipients (∼1/105 spleen cells), suggesting that stimulation by MHC class I–bearing cells was not required for the persistence of donor CTLs in vivo. In contrast, the frequency of donor OVA-CTLs in spleen cells of IL-2−/− mice (∼1/3 × 106 spleen cells) was much lower than in normal recipients, indicating that bystander IL-2 provided essential signals for the long-term maintenance of donor CTL in vivo.


Antigen is required for the activation of effector activities, whereas interleukin 2 Is required for the maintenance of memory in ovalbumin-specific, CD8+ cytotoxic T lymphocytes.

Ke Y, Ma H, Kapp JA - J. Exp. Med. (1998)

Precursor frequency of donor CTLs in recipient spleen cells. OVA-CTLs (5  × 106) were adoptively transferred into unirradiated, syngeneic normal, β2m−/− or IL-2−/−  mice. After 5 wk, recipients  were killed and spleen cells from  several mice were pooled and titrated in 24 wells of 96-well  plates. Irradiated E.G7-OVA,  syngeneic filler cells, and Con A  supernatant were added to the  cultures. After incubation at 37°C for 1 wk, the wells were restimulated  as described above. After an additional week in culture, the cytolytic activity of the recovered cells was tested using 51Cr-labeled E.G7-OVA targets. The log of the percentage of negative wells was plotted on the ordinate and the number of spleen cells on the abscissa.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199192&req=5

Figure 8: Precursor frequency of donor CTLs in recipient spleen cells. OVA-CTLs (5 × 106) were adoptively transferred into unirradiated, syngeneic normal, β2m−/− or IL-2−/− mice. After 5 wk, recipients were killed and spleen cells from several mice were pooled and titrated in 24 wells of 96-well plates. Irradiated E.G7-OVA, syngeneic filler cells, and Con A supernatant were added to the cultures. After incubation at 37°C for 1 wk, the wells were restimulated as described above. After an additional week in culture, the cytolytic activity of the recovered cells was tested using 51Cr-labeled E.G7-OVA targets. The log of the percentage of negative wells was plotted on the ordinate and the number of spleen cells on the abscissa.
Mentions: The requirements for persistence of OVA-CTLs were examined next. To test whether memory was maintained by stimulation with cross-reactive peptides complexed to MHC class I, β2m knockout recipients were used. Because OVA-CTLs do not produce IL-2, the potential role of host IL-2 in long-term persistence memory could be addressed using IL-2 knockout mice. 5 wk after transfer, spleen cells from recipient mice were restimulated in vitro with E.G7-OVA, syngeneic filler cells, and IL-2. The frequencies of donor OVA-CTLs in the host spleen cells were then analyzed. As shown in Fig. 8, the frequency of donor OVA-CTLs in spleen cells from β2m−/− mice was in the same order of magnitude as in normal recipients (∼1/105 spleen cells), suggesting that stimulation by MHC class I–bearing cells was not required for the persistence of donor CTLs in vivo. In contrast, the frequency of donor OVA-CTLs in spleen cells of IL-2−/− mice (∼1/3 × 106 spleen cells) was much lower than in normal recipients, indicating that bystander IL-2 provided essential signals for the long-term maintenance of donor CTL in vivo.

Bottom Line: Thus, the effector functions of these CTLs were rapidly induced by T cell receptor (TCR) occupancy.In the absence of OVA, the precursor frequency was identical in spleens of normal and beta2-microglobulin knockout recipients, but significantly less in IL-2 knockout mice.The decline of memory in the absence of IL-2 supports data from other investigators, suggesting that cell cycling is important to the maintenance of CD8+ T cell memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322, USA.

ABSTRACT
The mechanisms that maintain memory in T cells are not completely understood. We have investigated the role of antigen and interleukin (IL)-2 in the growth and maintenance of CD8+ T cells using a cytolytic T cell line specific for ovalbumin (OVA)257-264 presented by H-2Kb. This line does not secrete IL-4 or IL-2; hence, stimulation with the OVA-transfected EL4 line (E.G7-OVA) does not induce proliferation without addition of exogenous growth factors. Furthermore, this line can be maintained continuously by weekly addition of irradiated, splenic filler cells and IL-2, with or without E.G7-OVA. Although IL-2 induced proliferation of these cytotoxic T lymphocytes (CTLs), production of interferon gamma and tumor necrosis factor alpha required stimulation of the CTL with E. G7-OVA. The kinetics of lymphokine secretion after stimulation by E. G7-OVA were the same whether the CTL had been maintained with or without antigen (Ag). In addition, both CTL lines killed E.G7-OVA target cells within 4 h. Thus, the effector functions of these CTLs were rapidly induced by T cell receptor (TCR) occupancy. CTLs cultured with or without Ag also served as memory T cells when parked for 100 d in unirradiated, syngeneic recipients without OVA. In the absence of OVA, the precursor frequency was identical in spleens of normal and beta2-microglobulin knockout recipients, but significantly less in IL-2 knockout mice. The decline of memory in the absence of IL-2 supports data from other investigators, suggesting that cell cycling is important to the maintenance of CD8+ T cell memory. These data also suggest that stimulation of OVA-specific CTLs by lymphokines seems to be more important to maintaining memory than stimulation of TCRs by cross-reactive peptides complexed to class I molecules.

Show MeSH
Related in: MedlinePlus