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Lack of coreceptor allows survival of chronically stimulated double-negative alpha/beta T cells: implications for autoimmunity.

Hamad AR, Srikrishnan A, Mirmonsef P, Broeren CP, June CH, Pardoll D, Schneck JP - J. Exp. Med. (2001)

Bottom Line: Enhanced survival of CD4(-/-) T cells was due to decreased apoptosis rather than enhanced proliferation.Similarly, circumvention of the CD4/MHC interaction by using a surrogate TCR ligand that does not engage CD4 led to significant enhancement of CD4(+/+) cells than when stimulated with MHC/peptide.Together, these results indicate that coreceptor engagement controls expansion of normal T cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. ahamad@jhmi.edu

ABSTRACT
Lymphoproliferative diseases are characterized by massive accumulation of CD4(-)CD8(-)B220(+) (double-negative [DN]) T cells in peripheral organs. Although evidence indicates these cells are derived from mature autoreactive alpha/beta T cells, the significance of coreceptor downregulation is not known. In this study, we examined the role CD4 coreceptor plays in the survival of repeatedly stimulated T cells. CD4(+/+) and CD4(-/-) T cells from AND T cell receptor (TCR) transgenic mice exhibited similar phenotypes after antigenic stimulation, but the CD4(-/-) T cells survived in much larger numbers than the CD4(+/+) cells upon primary and secondary major histocompatibility complex (MHC)/peptide stimulation. Enhanced survival of CD4(-/-) T cells was due to decreased apoptosis rather than enhanced proliferation. Similarly, circumvention of the CD4/MHC interaction by using a surrogate TCR ligand that does not engage CD4 led to significant enhancement of CD4(+/+) cells than when stimulated with MHC/peptide. Finally, we generated DN B220(+) T cells using an in vitro model system and showed they were more tolerant to chronic stimulation than CD4(+/+) cells. Together, these results indicate that coreceptor engagement controls expansion of normal T cells. In the absence of coreceptor, T cells survive chronic stimulation and express B220 as seen in autoimmune lymphoproliferative diseases.

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Reduced apoptosis of activated CD4+/+ T cells leads to generation of DN T cells. (A) Purified CD4+/+ T cells were stimulated with MHC/peptide (left) or anti-CD3 (right) beads for 6 d and then stained and analyzed by flow cytometry. We gated on TCR+ cells and determined the percentage of CD4+ and apoptotic (annexin V+) cells in each culture. Cells in the left lower quadrant were DN T cells, as they lack both CD4 and CD8 (data not shown) coreceptors. (B) DN T cells are specific for I-Ek-MCC. Cells were collected from MHC/peptide (left) or anti-CD3 (right) cultures and stained simultaneously with I-Ek-MCC dimer and anti-TCRβ (H597) mAb and analyzed by flow cytometry. All cells including DN T cells in anti-CD3 culture stained positive with I-Ek-MCC indicating they were all expressing AND TCR transgene.
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Figure 5: Reduced apoptosis of activated CD4+/+ T cells leads to generation of DN T cells. (A) Purified CD4+/+ T cells were stimulated with MHC/peptide (left) or anti-CD3 (right) beads for 6 d and then stained and analyzed by flow cytometry. We gated on TCR+ cells and determined the percentage of CD4+ and apoptotic (annexin V+) cells in each culture. Cells in the left lower quadrant were DN T cells, as they lack both CD4 and CD8 (data not shown) coreceptors. (B) DN T cells are specific for I-Ek-MCC. Cells were collected from MHC/peptide (left) or anti-CD3 (right) cultures and stained simultaneously with I-Ek-MCC dimer and anti-TCRβ (H597) mAb and analyzed by flow cytometry. All cells including DN T cells in anti-CD3 culture stained positive with I-Ek-MCC indicating they were all expressing AND TCR transgene.

Mentions: The accumulation of DN T cells is seen most prominently in autoimmune diseases characterized by defects in Fas-mediated AICD 28 but noticeably absent in other autoimmune diseases. This suggests a link between impaired AICD and development of DN T cells. The differential ability of MHC/peptide and anti-CD3 to induce apoptosis allowed us the opportunity to study the impact of reduced apoptosis of activated CD4+/+ T cells on the generation of DN T cells. We stimulated highly purified CD4+/+ T cells for 6 d with either MHC/peptide or anti-CD3 beads and determined the percentages of CD4-negative and apoptotic T cells in each culture. The MHC/peptide stimulation resulted in a significant number (22%) of apoptotic T cells but few (3%) CD4-negative T cells (Fig. 5 A). Conversely, a significant number (31%) of CD4-negative T cells and few (5%) apoptotic cells were detected in the anti-CD3–stimulated culture. Thus, it appears that reducing apoptosis of activated T cells by excluding direct CD4 engagement leads to accumulation of CD4-negative T cells.


Lack of coreceptor allows survival of chronically stimulated double-negative alpha/beta T cells: implications for autoimmunity.

Hamad AR, Srikrishnan A, Mirmonsef P, Broeren CP, June CH, Pardoll D, Schneck JP - J. Exp. Med. (2001)

Reduced apoptosis of activated CD4+/+ T cells leads to generation of DN T cells. (A) Purified CD4+/+ T cells were stimulated with MHC/peptide (left) or anti-CD3 (right) beads for 6 d and then stained and analyzed by flow cytometry. We gated on TCR+ cells and determined the percentage of CD4+ and apoptotic (annexin V+) cells in each culture. Cells in the left lower quadrant were DN T cells, as they lack both CD4 and CD8 (data not shown) coreceptors. (B) DN T cells are specific for I-Ek-MCC. Cells were collected from MHC/peptide (left) or anti-CD3 (right) cultures and stained simultaneously with I-Ek-MCC dimer and anti-TCRβ (H597) mAb and analyzed by flow cytometry. All cells including DN T cells in anti-CD3 culture stained positive with I-Ek-MCC indicating they were all expressing AND TCR transgene.
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Related In: Results  -  Collection

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Figure 5: Reduced apoptosis of activated CD4+/+ T cells leads to generation of DN T cells. (A) Purified CD4+/+ T cells were stimulated with MHC/peptide (left) or anti-CD3 (right) beads for 6 d and then stained and analyzed by flow cytometry. We gated on TCR+ cells and determined the percentage of CD4+ and apoptotic (annexin V+) cells in each culture. Cells in the left lower quadrant were DN T cells, as they lack both CD4 and CD8 (data not shown) coreceptors. (B) DN T cells are specific for I-Ek-MCC. Cells were collected from MHC/peptide (left) or anti-CD3 (right) cultures and stained simultaneously with I-Ek-MCC dimer and anti-TCRβ (H597) mAb and analyzed by flow cytometry. All cells including DN T cells in anti-CD3 culture stained positive with I-Ek-MCC indicating they were all expressing AND TCR transgene.
Mentions: The accumulation of DN T cells is seen most prominently in autoimmune diseases characterized by defects in Fas-mediated AICD 28 but noticeably absent in other autoimmune diseases. This suggests a link between impaired AICD and development of DN T cells. The differential ability of MHC/peptide and anti-CD3 to induce apoptosis allowed us the opportunity to study the impact of reduced apoptosis of activated CD4+/+ T cells on the generation of DN T cells. We stimulated highly purified CD4+/+ T cells for 6 d with either MHC/peptide or anti-CD3 beads and determined the percentages of CD4-negative and apoptotic T cells in each culture. The MHC/peptide stimulation resulted in a significant number (22%) of apoptotic T cells but few (3%) CD4-negative T cells (Fig. 5 A). Conversely, a significant number (31%) of CD4-negative T cells and few (5%) apoptotic cells were detected in the anti-CD3–stimulated culture. Thus, it appears that reducing apoptosis of activated T cells by excluding direct CD4 engagement leads to accumulation of CD4-negative T cells.

Bottom Line: Enhanced survival of CD4(-/-) T cells was due to decreased apoptosis rather than enhanced proliferation.Similarly, circumvention of the CD4/MHC interaction by using a surrogate TCR ligand that does not engage CD4 led to significant enhancement of CD4(+/+) cells than when stimulated with MHC/peptide.Together, these results indicate that coreceptor engagement controls expansion of normal T cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. ahamad@jhmi.edu

ABSTRACT
Lymphoproliferative diseases are characterized by massive accumulation of CD4(-)CD8(-)B220(+) (double-negative [DN]) T cells in peripheral organs. Although evidence indicates these cells are derived from mature autoreactive alpha/beta T cells, the significance of coreceptor downregulation is not known. In this study, we examined the role CD4 coreceptor plays in the survival of repeatedly stimulated T cells. CD4(+/+) and CD4(-/-) T cells from AND T cell receptor (TCR) transgenic mice exhibited similar phenotypes after antigenic stimulation, but the CD4(-/-) T cells survived in much larger numbers than the CD4(+/+) cells upon primary and secondary major histocompatibility complex (MHC)/peptide stimulation. Enhanced survival of CD4(-/-) T cells was due to decreased apoptosis rather than enhanced proliferation. Similarly, circumvention of the CD4/MHC interaction by using a surrogate TCR ligand that does not engage CD4 led to significant enhancement of CD4(+/+) cells than when stimulated with MHC/peptide. Finally, we generated DN B220(+) T cells using an in vitro model system and showed they were more tolerant to chronic stimulation than CD4(+/+) cells. Together, these results indicate that coreceptor engagement controls expansion of normal T cells. In the absence of coreceptor, T cells survive chronic stimulation and express B220 as seen in autoimmune lymphoproliferative diseases.

Show MeSH
Related in: MedlinePlus