Cutting edge: dendritic cell-restricted antigen presentation initiates the follicular helper T cell program but cannot complete ultimate effector differentiation - PubMed (original) (raw)

Cutting edge: dendritic cell-restricted antigen presentation initiates the follicular helper T cell program but cannot complete ultimate effector differentiation

Radhika Goenka et al. J Immunol. 2011.

Abstract

Follicular helper T (T(FH)) cells are critical for germinal center (GC) formation. The processes that drive their generation and effector potential remain unclear. In this study, we define requirements for MHC class II APCs in murine T(FH) cell formation by either transiently ablating or restricting Ag presentation to dendritic cells (DCs). We find that cognate interactions with DCs are necessary and sufficient to prime CD4(+) T cells toward a CXCR5(+)ICOS(+)Bcl6(+) T(FH) cell intermediate. However, in the absence of additional APCs, these T(FH) cells fail to produce IL-21. Furthermore, in vitro priming of naive T cells by B cells engenders optimal production of IL-21, which induces a GC B cell transcriptional profile. These results support a multistep model for effector T(FH) cell priming and GC initiation, in which DCs are necessary and sufficient to induce a T(FH) cell intermediate that requires additional interactions with distinct APCs for full effector function.

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Figures

Figure 1

DCs are necessary for initiating TFH priming. WT and CD11cDTR mice were treated with DT and infected with T. gondii as described (16). (A) Numbers of TFH (CD4+CXCR5+ICOS+) were calculated at day 7 p.i. Data are pooled from two experiments (n>8 per group) (B) Representative FACS plots of CXCR5 and ICOS expression on CD4+ T cells in WT or CD11cDTR treated with DT. ** denotes statistical significance of p<0.01 in a 2-tailed t test at α=0.05

Figure 2

Cognate interactions by dendritic cells are sufficient for generation of TFH cells. 106 CFSE labeled CD90.1+ OTII T cells were transferred into either WT or CD11c/Aβbmice and mice were immunized with NP-OVA/alum. (A) Representative FACS gating strategy for identification of splenic OTII T cells (CD19− TCRβ+ CD4+ CD90.1+). OTII TFH cells were identified as CD62L− CXCR5+ cells. CFSE dilution of transferred OT-II cells was assessed (middle panel). (B) Total number of splenic OTII and OTII TFH present in immunized WT or CD11c/Aβb recipients at day 8 p.i. or in non-immunized WT mice at d8 post-transfer (n=4–5 mice, representative of >5 experiments). (C) Representative histogram overlay of ICOS and Bcl6 staining intensity on OTII TFH generated in WT or CD11c/Aβb mice and naïve endogenous CD4+ T cells (CD19− TCRβ+ CD4+CD62L+) present in WT mice (D) Bcl-6 mRNA in FACS sorted OT-II TFH generated in WT or CD11c/Aβ mice at d7 p.i.. relative to naive OTII cells (representative of 3 experiments) (E) Confocal micrographs of splenic sections to identify CD90.1+ OTII along with PNA+ GCs and IgD+ naïve B cells in the follicle. Scale bar denotes 50 μm.

Figure 3

DC restricted antigen presentation is insufficient for the generation of GC TFH 106 OTII T cells were transferred into WT and CD11c/Aβb mice and mice were immunized with NP-OVA/alum. (A) Representative FACS gating strategy to identify PD1+CXCR5+ within activated OTII TFH (CD19−TCRβ+CD4+CD90.1+CD62L−) in immunized WT or CD11c/Aβb on d7 p.i. as well as naïve WT CD4+ T cells as a staining control. The PD1+ cells were parsed into PD1hi (GC TFH) and PD1int populations. (B) The total number of OTII GC TFH in WT or CD11c/Aβb mice on d7 p.i. (n=4–5) (C) Histogram overlay of GL7 staining on various subsets gated in (A) (n=4–5 mice). Results are representative of 3 experiments. ** denotes statistical significance of p<0.01 in a 2-tailed t test at α=0.05.

Figure 4

Reduced expression of IL-21 in TFH cells primed in CD11c/Aβb mice. (A) Expression of IL-21 transcript in FACS sorted OT-II TFH generated in WT or CD11c/Aβb mice at d7 p.i. normalized to naïve OTII cells. Results are representative of 3 experiments. (B) Relative expression of Bcl6 and IL-21 in OTII cells polarized towards TFH lineage using splenic CD11c+ or CD23+ cells as APCs compared to Th0 condition. Results are representative of 2 experiments. (C) QPCR analysis of Bcl6 and Blimp1 on CD23+ cells stimulated with F(ab)2 fragments of αIgM alone or in combination with αCD40 with or without IL-21 for 3 days. Results pooled from 3 experiments.

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Cutting edge: dendritic cell-restricted antigen presentation initiates the follicular helper T cell program but cannot complete ultimate effector differentiation - PubMed (original) (raw)