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FcRγ controls the fas-dependent regulatory function of lymphoproliferative double negative T cells.

Juvet SC, Thomson CW, Kim EY, Han M, Zhang L - PLoS ONE (2013)

Bottom Line: We have shown previously that a significant proportion of DN T cells express FcRγ, and that this molecule is required for TCR transgenic DN T cells to suppress allogeneic immune responses.Furthermore, FcRγ acted in a cell-intrinsic fashion to limit DN T cell accumulation by increasing the rate of apoptosis in proliferated cells.These results indicate that FcRγ can confer Fas-dependent regulatory properties on LPR DN T cells, and suggest that FcRγ may be a novel marker for functional DN Tregs.

View Article: PubMed Central - PubMed

Affiliation: Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.

ABSTRACT
Patients with autoimmune lymphoproliferative syndrome (ALPS) and lymphoproliferation (LPR) mice are deficient in Fas, and accumulate large numbers of αβ-TCR(+), CD4(-), CD8(-) double negative (DN) T cells. The function of these DN T cells remains largely unknown. The common γ subunit of the activating Fc receptors, FcRγ, plays an important role in mediating innate immune responses. We have shown previously that a significant proportion of DN T cells express FcRγ, and that this molecule is required for TCR transgenic DN T cells to suppress allogeneic immune responses. Whether FcRγ plays a critical role in LPR DN T cell-mediated suppression of immune responses to auto and allo-antigens is not known. Here, we demonstrated that FcRγ(+), but not FcRγ(-) LPR DN T cells could suppress Fas(+) CD4(+) and CD8(+) T cell proliferation in vitro and attenuated CD4(+) T cell-mediated graft-versus host disease. Although FcRγ expression did not allow LPR DN T cells to inhibit the expansion of Fas-deficient cells within the LPR context, adoptive transfer of FcRγ(+), but not FcRγ(-), DN T cells inhibited lymphoproliferation in generalized lymphoproliferative disease (GLD) mice. Furthermore, FcRγ acted in a cell-intrinsic fashion to limit DN T cell accumulation by increasing the rate of apoptosis in proliferated cells. These results indicate that FcRγ can confer Fas-dependent regulatory properties on LPR DN T cells, and suggest that FcRγ may be a novel marker for functional DN Tregs.

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FcRγ-expressing DN T cells are a distinct effector-memory subset in both B6 and LPR mice.A. Freshly isolated B6 (n = 3, left column) and LPR (n = 4, right column) splenocytes were stained for TCRβ, CD4, CD8, NK1.1, CD16/32, CD44, and CD62L expression and examined by flow cytometry. Within the DN T cell gate (TCRβ+, CD4−, CD8−, NK1.1−), expression of CD44 (top row) and CD62L (bottom row) in the CD16+ (shaded) and CD16− (unshaded) subsets was plotted. B. Median fluorescence intensity (MFI) of CD44 staining in CD16+ and CD16− DN T cells for all 7 mice is shown. Unpaired t tests p = 0.006 (CD16+ vs. CD16− B6 DN T cells) and p = 0.0009 (CD16+ vs. CD16− LPR DN T cells). C. MFI of CD62L staining in CD16+ and CD16− DN T cells for all 7 mice is shown. Unpaired t tests p = 0.0036 (CD16+ vs. CD16− B6 DN T cells) and p = 0.0165 (CD16+ vs. CD16− LPR DN T cells).
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pone-0065253-g001: FcRγ-expressing DN T cells are a distinct effector-memory subset in both B6 and LPR mice.A. Freshly isolated B6 (n = 3, left column) and LPR (n = 4, right column) splenocytes were stained for TCRβ, CD4, CD8, NK1.1, CD16/32, CD44, and CD62L expression and examined by flow cytometry. Within the DN T cell gate (TCRβ+, CD4−, CD8−, NK1.1−), expression of CD44 (top row) and CD62L (bottom row) in the CD16+ (shaded) and CD16− (unshaded) subsets was plotted. B. Median fluorescence intensity (MFI) of CD44 staining in CD16+ and CD16− DN T cells for all 7 mice is shown. Unpaired t tests p = 0.006 (CD16+ vs. CD16− B6 DN T cells) and p = 0.0009 (CD16+ vs. CD16− LPR DN T cells). C. MFI of CD62L staining in CD16+ and CD16− DN T cells for all 7 mice is shown. Unpaired t tests p = 0.0036 (CD16+ vs. CD16− B6 DN T cells) and p = 0.0165 (CD16+ vs. CD16− LPR DN T cells).

Mentions: FcRγ is well-known to be expressed in myeloid cells, NK cells and B cells but its expression in T cells is less common. We recently observed that in contrast to CD4+ or CD8+ T cells, a significant proportion of DN T cells co-expresses FcRγ and surface Fcγ receptor IIIA (CD16) [26]. Since little is known about FcRγ+ DN T cells, we further characterized this population of cells. To examine their expression of T cell activation and memory markers, splenocytes from B6 and LPR mice were stained for expression of TCRβ, CD4, CD8, NK1.1, CD16/32 and CD44, CD62L, or CD25. As shown in Fig. 1A–C, CD16+ DN T cells (TCRβ+, CD4−, CD8−, NK1.1−) exhibited higher levels of CD44 expression, and lower levels of CD62L expression, in comparison with CD16− DN T cells within the same mice. Although LPR DN T cells are known to have an activated phenotype with high levels of CD44 expression [9], [27], we observed even higher levels of CD44 expression on the CD16+ subset (Fig. 1A, top right panel and Fig. 1B). A higher level of CD25 expression was also seen in the CD16-expressing subset (data not shown). Hence in both normal B6 mice and Fas-deficient LPR mice, an FcRγ-expressing subset of DN T cells displays an effector-memory phenotype.


FcRγ controls the fas-dependent regulatory function of lymphoproliferative double negative T cells.

Juvet SC, Thomson CW, Kim EY, Han M, Zhang L - PLoS ONE (2013)

FcRγ-expressing DN T cells are a distinct effector-memory subset in both B6 and LPR mice.A. Freshly isolated B6 (n = 3, left column) and LPR (n = 4, right column) splenocytes were stained for TCRβ, CD4, CD8, NK1.1, CD16/32, CD44, and CD62L expression and examined by flow cytometry. Within the DN T cell gate (TCRβ+, CD4−, CD8−, NK1.1−), expression of CD44 (top row) and CD62L (bottom row) in the CD16+ (shaded) and CD16− (unshaded) subsets was plotted. B. Median fluorescence intensity (MFI) of CD44 staining in CD16+ and CD16− DN T cells for all 7 mice is shown. Unpaired t tests p = 0.006 (CD16+ vs. CD16− B6 DN T cells) and p = 0.0009 (CD16+ vs. CD16− LPR DN T cells). C. MFI of CD62L staining in CD16+ and CD16− DN T cells for all 7 mice is shown. Unpaired t tests p = 0.0036 (CD16+ vs. CD16− B6 DN T cells) and p = 0.0165 (CD16+ vs. CD16− LPR DN T cells).
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pone-0065253-g001: FcRγ-expressing DN T cells are a distinct effector-memory subset in both B6 and LPR mice.A. Freshly isolated B6 (n = 3, left column) and LPR (n = 4, right column) splenocytes were stained for TCRβ, CD4, CD8, NK1.1, CD16/32, CD44, and CD62L expression and examined by flow cytometry. Within the DN T cell gate (TCRβ+, CD4−, CD8−, NK1.1−), expression of CD44 (top row) and CD62L (bottom row) in the CD16+ (shaded) and CD16− (unshaded) subsets was plotted. B. Median fluorescence intensity (MFI) of CD44 staining in CD16+ and CD16− DN T cells for all 7 mice is shown. Unpaired t tests p = 0.006 (CD16+ vs. CD16− B6 DN T cells) and p = 0.0009 (CD16+ vs. CD16− LPR DN T cells). C. MFI of CD62L staining in CD16+ and CD16− DN T cells for all 7 mice is shown. Unpaired t tests p = 0.0036 (CD16+ vs. CD16− B6 DN T cells) and p = 0.0165 (CD16+ vs. CD16− LPR DN T cells).
Mentions: FcRγ is well-known to be expressed in myeloid cells, NK cells and B cells but its expression in T cells is less common. We recently observed that in contrast to CD4+ or CD8+ T cells, a significant proportion of DN T cells co-expresses FcRγ and surface Fcγ receptor IIIA (CD16) [26]. Since little is known about FcRγ+ DN T cells, we further characterized this population of cells. To examine their expression of T cell activation and memory markers, splenocytes from B6 and LPR mice were stained for expression of TCRβ, CD4, CD8, NK1.1, CD16/32 and CD44, CD62L, or CD25. As shown in Fig. 1A–C, CD16+ DN T cells (TCRβ+, CD4−, CD8−, NK1.1−) exhibited higher levels of CD44 expression, and lower levels of CD62L expression, in comparison with CD16− DN T cells within the same mice. Although LPR DN T cells are known to have an activated phenotype with high levels of CD44 expression [9], [27], we observed even higher levels of CD44 expression on the CD16+ subset (Fig. 1A, top right panel and Fig. 1B). A higher level of CD25 expression was also seen in the CD16-expressing subset (data not shown). Hence in both normal B6 mice and Fas-deficient LPR mice, an FcRγ-expressing subset of DN T cells displays an effector-memory phenotype.

Bottom Line: We have shown previously that a significant proportion of DN T cells express FcRγ, and that this molecule is required for TCR transgenic DN T cells to suppress allogeneic immune responses.Furthermore, FcRγ acted in a cell-intrinsic fashion to limit DN T cell accumulation by increasing the rate of apoptosis in proliferated cells.These results indicate that FcRγ can confer Fas-dependent regulatory properties on LPR DN T cells, and suggest that FcRγ may be a novel marker for functional DN Tregs.

View Article: PubMed Central - PubMed

Affiliation: Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.

ABSTRACT
Patients with autoimmune lymphoproliferative syndrome (ALPS) and lymphoproliferation (LPR) mice are deficient in Fas, and accumulate large numbers of αβ-TCR(+), CD4(-), CD8(-) double negative (DN) T cells. The function of these DN T cells remains largely unknown. The common γ subunit of the activating Fc receptors, FcRγ, plays an important role in mediating innate immune responses. We have shown previously that a significant proportion of DN T cells express FcRγ, and that this molecule is required for TCR transgenic DN T cells to suppress allogeneic immune responses. Whether FcRγ plays a critical role in LPR DN T cell-mediated suppression of immune responses to auto and allo-antigens is not known. Here, we demonstrated that FcRγ(+), but not FcRγ(-) LPR DN T cells could suppress Fas(+) CD4(+) and CD8(+) T cell proliferation in vitro and attenuated CD4(+) T cell-mediated graft-versus host disease. Although FcRγ expression did not allow LPR DN T cells to inhibit the expansion of Fas-deficient cells within the LPR context, adoptive transfer of FcRγ(+), but not FcRγ(-), DN T cells inhibited lymphoproliferation in generalized lymphoproliferative disease (GLD) mice. Furthermore, FcRγ acted in a cell-intrinsic fashion to limit DN T cell accumulation by increasing the rate of apoptosis in proliferated cells. These results indicate that FcRγ can confer Fas-dependent regulatory properties on LPR DN T cells, and suggest that FcRγ may be a novel marker for functional DN Tregs.

Show MeSH
Related in: MedlinePlus