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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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Fluorescence flow cytometric analysis of OVA-CTLs. OVA-CTLs were cocultured with irradiated, syngeneic filler cells and Con A  supernatant in the presence (A–C) or absence (D–F) of irradiated E.G7-OVA stimulators, as described in Fig. 1. After incubation at 37°C for 1 wk,  viable T cells were stained with (A and D) FITC-conjugated M1/9.3.4  (anti-CD45) or normal rat IgG, (B and E) FITC-conjugated 145-2C11(anti-CD3) or normal hamster IgG, or (C and F) PE-conjugated  3C7 (anti–IL-2R) or normal rat IgG. The results are presented as fluorescence histograms with the relative number of cells on the ordinate and the  relative fluorescence intensity on the abscissa.
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Figure 2: Fluorescence flow cytometric analysis of OVA-CTLs. OVA-CTLs were cocultured with irradiated, syngeneic filler cells and Con A supernatant in the presence (A–C) or absence (D–F) of irradiated E.G7-OVA stimulators, as described in Fig. 1. After incubation at 37°C for 1 wk, viable T cells were stained with (A and D) FITC-conjugated M1/9.3.4 (anti-CD45) or normal rat IgG, (B and E) FITC-conjugated 145-2C11(anti-CD3) or normal hamster IgG, or (C and F) PE-conjugated 3C7 (anti–IL-2R) or normal rat IgG. The results are presented as fluorescence histograms with the relative number of cells on the ordinate and the relative fluorescence intensity on the abscissa.

Mentions: Responses to IL-2 can be enhanced by antigen because antigen induces an increase in the density of IL-2R on CD8+ CTLs (21, 22). To verify that the IL-2–induced enhancement of lymphokine secretion that was observed in the previous experiment resulted from the upregulation of IL-2R by antigen, we cocultured OVA-CTLs with filler cells and IL-2 in the presence or absence of E.G7-OVA stimulators for 1 wk and then stained them with mAbs specific for CD45, CD3, or the α chain of IL-2R. There were no significant changes in the expression of CD45 between OVA-CTLs incubated with or without E.G7-OVA (Fig. 2, A and B). Expression of CD3 was slightly increased by stimulation with E.G7-OVA (Fig. 2, C and D). However, the IL-2R level expressed by stimulated OVA-CTLs (Fig. 2 F) was two to threefold higher than unstimulated CTLs (Fig. 2 E). Thus, triggering TCR by antigen upregulated IL-2R expression permitting IL-2 to enhance growth and lymphokine production.


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)

Fluorescence flow cytometric analysis of OVA-CTLs. OVA-CTLs were cocultured with irradiated, syngeneic filler cells and Con A  supernatant in the presence (A–C) or absence (D–F) of irradiated E.G7-OVA stimulators, as described in Fig. 1. After incubation at 37°C for 1 wk,  viable T cells were stained with (A and D) FITC-conjugated M1/9.3.4  (anti-CD45) or normal rat IgG, (B and E) FITC-conjugated 145-2C11(anti-CD3) or normal hamster IgG, or (C and F) PE-conjugated  3C7 (anti–IL-2R) or normal rat IgG. The results are presented as fluorescence histograms with the relative number of cells on the ordinate and the  relative fluorescence intensity on the abscissa.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199192&req=5

Figure 2: Fluorescence flow cytometric analysis of OVA-CTLs. OVA-CTLs were cocultured with irradiated, syngeneic filler cells and Con A supernatant in the presence (A–C) or absence (D–F) of irradiated E.G7-OVA stimulators, as described in Fig. 1. After incubation at 37°C for 1 wk, viable T cells were stained with (A and D) FITC-conjugated M1/9.3.4 (anti-CD45) or normal rat IgG, (B and E) FITC-conjugated 145-2C11(anti-CD3) or normal hamster IgG, or (C and F) PE-conjugated 3C7 (anti–IL-2R) or normal rat IgG. The results are presented as fluorescence histograms with the relative number of cells on the ordinate and the relative fluorescence intensity on the abscissa.
Mentions: Responses to IL-2 can be enhanced by antigen because antigen induces an increase in the density of IL-2R on CD8+ CTLs (21, 22). To verify that the IL-2–induced enhancement of lymphokine secretion that was observed in the previous experiment resulted from the upregulation of IL-2R by antigen, we cocultured OVA-CTLs with filler cells and IL-2 in the presence or absence of E.G7-OVA stimulators for 1 wk and then stained them with mAbs specific for CD45, CD3, or the α chain of IL-2R. There were no significant changes in the expression of CD45 between OVA-CTLs incubated with or without E.G7-OVA (Fig. 2, A and B). Expression of CD3 was slightly increased by stimulation with E.G7-OVA (Fig. 2, C and D). However, the IL-2R level expressed by stimulated OVA-CTLs (Fig. 2 F) was two to threefold higher than unstimulated CTLs (Fig. 2 E). Thus, triggering TCR by antigen upregulated IL-2R expression permitting IL-2 to enhance growth and lymphokine production.

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