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Medical Research Council Center for Immune Regulation, Institute for Biomedical Research, Birmingham Medical School, Birmingham, United Kingdom
| Abstract |
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| Introduction |
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This cluster of TNF family members share common signaling pathways through the TNF-related adaptor factor family (1, 2, 3, and 5, but not 4 or 6) (8); signals through these receptors enhance survival by up-regulation of the antiapoptotic proteins, Bcl-2 and Bcl-xL (9, 10). Others have shown that CD4 recall responses are impaired in mice deficient in OX40 signals (11, 12, 13), and we found that such mice have a modest defect in their capacity to sustain long-term Ab responses (1). Because of shared signaling pathways through OX40 and CD30, it seemed probable that CD30 signals from CD4+CD3 cells might compensate in OX40-deficient mice. In this report we have investigated the effects of CD30 alone and CD30 in concert with OX40 on the development and survival of Th2-primed CD4 cells. We found that CD30-deficient (CD30ko) mice had impaired capacity to sustain GC responses, and their secondary Ab responses were much reduced when they were reimmunized. The effects of CD30 on secondary Ab responses were even more marked when combined with OX40 deficiency. This was not due to a defect in T cell proliferation, because OX40/CD30 double-deficient (dko) transgenic cells proliferated as well as their normal counterparts, but failed to survive. This deficiency in T cell survival was associated with impaired retention in B follicles, and poor survival in vivo and in vitro when cocultured with CD4+CD3 cells. These data suggest that OX40 and CD30 signals act together to control the development of memory T cells to provide help for secondary Ab responses.
| Materials and Methods |
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Mice deficient in OX40 and CD30 were generated by crossing the two strains of single-knockout mice. F1 heterozygotes were backcrossed onto single-knockout mice and screened to identify mice that had undergone recombination to produce dko alleles. Identified recombinants were then bred together to generate homozygous dko mice. dko mice were subsequently bred with OTII mice to generate OTII dko mice.
Immunizations
For priming, groups of mice were immunized with alum-precipitated NP-chicken gammaglobulin (C
G; 100 µg/mouse i.p.), C
G alone (100 µg/mouse i.p.), or NP-OVA (200 µg/mouse i.p.) and killed at the indicated time points. Mice were boosted with soluble NP-C
G (100 µg/mouse i.p.) and killed 4 days later.
ELISA
Serum samples were analyzed by ELISA on NP15-BSA-, NP2-BSA-, and C
G-coated plates (1).
Immunohistology and quantitative microscopy
Frozen spleen sections were stained as previously described (14) with sheep anti-mouse IgD (The Binding Site) and rabbit IgG conjugated to NP or NP-C
G, followed by swine anti-rabbit IgG biotin or anti-C
G biotin and donkey anti-sheep peroxidase (The Binding Site), followed by StreptABComplex alkaline phosphatase (DakoCytomation).
To quantify the GC area or plasma cell number per unit spleen, we counted the number of intercepts on a 100-mm2 eyepiece graticule for Ag (NP or C
G)-specific GC or plasma cells at a magnification of x40. The total area of spleen section was measured by counting intercepts on a 100-mm2 acetate overlay.
In vitro T cell survival assays
Splenocytes from CD45.1 OTII mice and CD45.2 OTII knockout (OX40ko, CD30ko, and dko) mice were mixed so that the starting ratio of normal to knockout OTII cells was 1:1 (total of 106 cells/ml). They were cultured for 4 days with 1 µM OVA323339 peptide (15) under Th1 and Th2 conditions in vitro as previously described (1). After 4 days, the cells were washed and recultured with 105 CD4+CD3 cells from RAG-deficient mice. On day 10, the ratio of normal to knockout OTII CD4 T cells was checked by flow cytometry.
In vivo T cell survival assays
A final mixture of 1:1 normal:dko OTII cells (total of 107 cells/mouse) was labeled with the intracellular fluorescent dye CFSE (Molecular Probes) and transferred into RAG-deficient mice. The mice were immunized the next day with 200 µg of alum-precipitated NP-OVA. On day 3, spleens were taken, and the number of cell divisions was checked by flow cytometry. On day 21, spleen sections were stained by confocal microscopy, and the numbers of dko and normal OTII cells were enumerated in B and T cell areas as previously described (1).
Splenocytes or lymph node cells were cultured at a concentration of 106 cells/ml overnight with recombinant murine IL-7 (0.1100 ng/ml; PeproTech). They were stained for FACS analysis with mAbs to IL-7R
, OX40, OX40 ligand, CD30, and CD30 ligand. All these Abs together with those to CD3, CD4, CD8, CD45.1, and CD44 were obtained from BD Biosciences.
| Results |
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Primary day 7 anti-NP IgG (Fig. 1) and IgM (data not shown) Ab responses after immunization with a T-dependent protein Ag (alum-precipitated NP-C
G) were indistinguishable among groups of mice that were normal, CD30-deficient (CD30ko), or deficient in both CD30 and OX40 (dko). Although total IgG Abs to the hapten, NP, were not significantly different among the three groups (Fig. 1A), differences were observed in the production of high affinity Abs (measured by their capacity to bind NP2) on day 21 (Fig. 1, B and C). CD30ko and dko mice (p = 0.05) had lower titers of high affinity Abs than normal mice.
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G (Fig. 2, H and I). These observations were confirmed by quantitative analysis of GC areas on days 7 and 14 in normal, CD30ko, and dko mice (Fig. 1D).
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Cognate interactions between B and CD4 T cells are required to sustain GC and secure the output of memory B and plasma cells. We reasoned that the impaired production of high affinity Abs in dko mice could have been due to failure of T cell survival within the GC. To test this, we examined the capacity of T cells primed in CD30ko and dko mice to provide help for a secondary memory B cell response. Normal, CD30ko, and dko mice were primed with alum-precipitated NP-C
G and boosted with soluble NP-C
G 3 wk later. After 4 days, the peak of the secondary response in normal mice, the spleens were analyzed for Ag-specific plasma cells and GC. Whereas normal mice made an excellent secondary IgG response to the hapten, NP (Figs. 3A and 4A), and to the carrier protein, C
G (Figs. 3D and 4A), the secondary response to the carrier protein, C
G, was absent in dko mice (Fig. 3, C and F, and Fig. 4A). CD30ko mice made a small, but reproducible, secondary Ab response to both C
G and the hapten, NP, compared with dko mice (Fig. 3, B and E, and Fig. 4A).
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G, then they were boosted twice on days 21 and 35 with soluble NP-C
G, a poor immunogen for priming naive T cells. On day 39, normal mice developed high affinity Abs to NP (Fig. 4B). In contrast, no NP-specific serum Abs were elicited in dko mice, indicating a specific lack of T cell memory. The absence of help from memory T cells in dko mice was confirmed by the lack of NP-specific GC and plasma cells in the tissue (data not shown, but similar to those in Fig. 3, C and F). Survival of dko CD4 transgenic T cells in vivo is compromised
To visualize the T cell deficit in dko mice, we crossed dko mice with the TCR transgenic line, OTII, in which CD4 T cells express a TCR specific for a peptide from OVA (15). The CD45 allotype marked normal (CD45.1) and dko (CD45.2) CD4 T cells were transferred in a 1:1 ratio into RAG-deficient recipients that were immunized 1 day later with alum-precipitated NP-OVA, a Th2 immunogen (17). In the absence of immunization, neither dko nor normal T cells underwent any significant proliferation, because there was no dilution of the membrane dye CFSE (Fig. 5A). In contrast, 3 days after immunization, the cell division of dko and normal cells was similar (Fig. 5A). However, by day 7 there were markedly more normal cells (Fig. 5B). At 2 and 3 wk postimmunization, this bias was maintained at
7:1. Analysis of tissue sections in the reconstituted RAG-deficient mice revealed that the ratio of normal to dko cells was much higher in the B follicles, where primed T cells interact with CD4+CD3 cells (1), than in the T zone (Fig. 5C). This result appeared qualitatively similar to that we previously reported for OX40-deficient T cells in competition with their normal counterparts (1). The individual contributions of OX40 and CD30 to T cell rescue by CD4+CD3 cells were next examined in an in vitro survival assay.
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To test the relative capacities of OX40ko, CD30ko, and dko CD4 T cells to be rescued by CD4+CD3 cells, we used an in vitro assay in which gene-deficient (CD45.2) and normal (CD45.1) OTII CD4 T cells (ratio 1:1) were stimulated with peptide and cytokines (IL-4 and anti-IL-12 for Th2 or IL-12 and anti-IL-4 for Th1 conditions) for 4 days (Fig. 6). At this time there was no significant change in the ratio of normal to OX40ko, CD30ko, or dko T cells. The cultures were then washed to remove exogenous peptide and cultured with fresh medium supplemented with CD4+CD3 cells. We have found that these conditions test the capacity of CD4+CD3 cells to rescue T cell survival; normal T cells do not proliferate under these conditions, but show reduced size, as assessed by forward scatter and decreased annexin staining, consistent with increased survival after several days of culture (1). In this assay on day 10, OX40ko Th2 cells showed decreased survival compared with normal counterparts (
1:3; Fig. 6A) similar to what we reported previously (1). In the same assay performed contemporaneously, CD30ko Th2 cells showed a similar (1:3) deficit (Fig. 6B). In contrast to normal T cells, dko Th2 cells cultured with CD4+CD3 cells showed markedly impaired survival (1:8.3; Fig. 6C); this indicates that OX40 and CD30 signals are additive for Th2 survival. In contrast, Th1-differentiated OX40ko, CD30ko, or dko cells showed no significant survival disadvantage when cultured with CD4+CD3 cells.
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The impaired secondary Ab responses in dko mice suggested that the survival of recirculating memory T cells (18) might depend on OX40 and CD30 signals. Although CD4+CD3 cells are common in B cell areas, they are also found in the outer T zone and marginal sinus of the spleen (1), sites where they could interact with memory T cells. However, CD4 memory T cells, identified by their expression of high levels of CD44, show only modest expression of OX40 and no CD30 expression (Fig. 7A). The cytokine, IL-7, which is produced by lymphoid stromal cells, has been implicated in the survival of IL-7R-positive (19, 20) CD4 (21, 22, 23) and CD8 (24, 25) memory T cells. We reasoned that IL-7 might exert its effects by regulating the expression of OX40 and CD30, independently of TCR stimulation, allowing memory T cells to receive survival signals from CD4+CD3 cells as they recirculated through secondary lymphoid tissue. To test this, we isolated memory T cells from RAG-deficient mice into which normal and dko OTII cells had been transferred and immunized 3 wk previously (day 21, Fig. 5B). Surviving normal and dko cells from these RAG-deficient recipients expressed comparable levels of IL-7R, and all normal and the few remaining dko T cells had the CD44high memory phenotype (data not shown). Freshly isolated splenic memory T cells expressed only low levels of OX40 and no CD30. However, after culture with IL-7 over a wide concentration range (0.1100 ng/ml IL-7), OX40, but not its ligand, was induced (Fig. 7B, data shown are for 10 ng/ml IL-7). In contrast, CD30 expression was apparently not induced, although there was induction of CD30 ligand. We observed signaling-induced down-modulation of IL-7R expression by addition of IL-7 (Fig. 7B); it is therefore possible that CD30 expression is induced by IL-7, but that it is rapidly attenuated by signals from the ligand. The receptor induction shown was also observed on T cells isolated from cervical and axillary lymph nodes, sites remote from the point of immunization (data not shown). The induction was not just a feature of transgenic cells, because analysis of CD44high CD4+ cells from normal mice also showed strong induction of OX40 and CD30 ligand (Fig. 7A). In contrast, OX40 is not induced on naive CD44 CD4 T cells.
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| Discussion |
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-chain, act together to foster GC development; mice deficient in both signaling pathways have impaired GC development and Ig class switching (26). Th2-primed cells have been linked with preferential migration into B follicles with GC development (6, 7) and strongly express OX40 and CD30 (1, 5). In this report we have investigated the roles of OX40 and CD30 signals in maintaining Ab responses that depend on follicular T cells. It has previously been reported that OX40-deficient mice have normal primary and virtually normal secondary B cell responses (1, 11, 12, 27, 28). We report in this study that primary Ab responses in CD30-deficient mice are also normal, but that GC responses are not sustained, and recall secondary Ab responses are impaired. Mice deficient in both CD30 and OX40 show an even more dramatic phenotype. Again, primary Ab responses are normal, but dko mice show impaired affinity maturation because of failure to sustain GCs, and dko mice fail to make recall secondary Ab responses after reimmunization. We found that the early proliferation of T cells deficient in both CD30 and OX40 was comparable to that of normal T cells, and this correlated with their capacity to provide help for the primary B cell response. However, dko cells failed to survive compared with their normal counterparts both in vitro and in vivo under Th2 conditions of immunization. In vitro analysis of the capacity of CD4+CD3 cells to rescue OX40ko, CD30ko, and dko Th2 cells compared with their normal counterparts revealed an additive role for OX40 and CD30 in Th2 cell survival. Analysis of tissue sections showed that the failure to survive was particularly evident in B follicles, where we have previously demonstrated that follicular T cells interact with CD4+CD3 cells. Although activated B cells can express OX40 ligand and have been implicated in sustaining GC T cells (29), CD4+CD3 cells differ from B cells in that they express OX40 ligand and CD30 ligand in the absence of stimulation (1). The close association of GC T cells with CD4+CD3 cells makes it likely that they continue to receive OX40 and CD30 signals from them during the course of the GC reaction. We have previously shown that coculture of Th2 effectors with CD4+CD3 cells is associated with their survival, but not proliferation (1). In this study we report that the effects of OX40 and CD30 on Th2 survival are synergistic and suggest that this may be particularly important during the selection of rare B cell mutants bearing high affinity Ag receptors in GCs when the supply of Ag driving the B cell response is limiting.
Our studies also showed that the capacity of dko T cells to provide immediate help for secondary Ab responses was deficient in both CD30ko and dko mice. However, freshly isolated memory CD4 T cells expressed little OX40 and no CD30, and it was not clear, therefore, how they might obtain access to survival signals from CD4+CD3 cells. One possibility was that IL-7 signals, which have been implicated in CD4 T cell survival, might regulate the expression of OX40 and CD30 (21, 22, 23). When we isolated OTII transgenic T cells from RAG-deficient recipients immunized 3 wk previously (dko and normal cells were CD44high memory phenotype), we found that both dko and normal populations expressed comparable levels of IL-7R. This indicated that OX40 and CD30 signals were not essential for the induction of IL-7R on the memory T cell population, and this was not the explanation for the failure of dko cells to survive. However, the freshly isolated CD44high CD4 memory population also expressed low levels of OX40 and no CD30. However, the addition of exogenous IL-7 up-regulated OX40 expression. Although CD30 expression was not induced, there was clear induction of CD30 ligand on the CD44high CD4 population. We observed IL-7R-mediated down-modulation by addition of IL-7, so we are investigating the possibility that memory T cells up-regulate both CD30 and its ligand, but that CD30 expression is rapidly down-modulated.
On the basis of these results, we propose the following model for maintenance of effective T cell help for Ab responses. Dendritic cell-primed Th2 effectors migrate into B follicles, where Ag-driven expression of OX40 and CD30 allows access to the survival signals through these molecules from CD4+CD3 cells. The constitutive expression of the ligands on CD4+CD3 cells is particularly important in the late phase of the GC reaction when Ag is limiting, but when it is crucial to select rare B cell mutants with high affinity. In addition to this Ag-driven expression, there is Ag-independent, IL-7R-mediated OX40 induction on CD4 T cells primed to provide immediate help for secondary B cell responses. We suggest that OX40 is induced on these cells by IL-7 produced by lymphoid stromal cells. Induction of OX40 by IL-7 then allows these T cells to receive continued survival signals from CD4+CD3 cells. Maintaining a population of primed T cells adjacent to B cell areas ensures that secondary Ab responses occur with optimal efficiency.
In summary, our data reveal two important features of T cell help for Ab production. First, it is regulated by partially redundant signals through OX40 and CD30. Second, it is sustained by a chain of events linking IL-7 signals, OX40 and CD30 expression, and signals from CD4+CD3 cells. This information opens up new possibilities for the selective targeting of pathogenic Th2-mediated Ab responses, such as systemic lupus erythematosus; blocking the signals through OX40 and CD30 or manipulating the expression of their ligands on CD4+CD3 cells should be effective approaches to unwanted Ab responses.
| Disclosures |
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| Acknowledgments |
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| Footnotes |
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1 This work was supported by a Wellcome Program Grant (to P.J.L.L.). ![]()
2 F.M.C.G. and M.-Y.K. contributed equally to this work. ![]()
3 Address correspondence and reprint requests to Dr. Peter J. L. Lane, Medical Research Council Center for Immune Regulation, Institute for Biomedical Research, Birmingham Medical School, Birmingham, U.K. B15 2TT. E-mail address: p.j.l.lane{at}bham.ac.uk ![]()
4 Abbreviations used in this paper: GC, germinal center; C
G, chicken gammaglobulin; dko, OX40 and CD30 double-deficient; NP-C
G, 4-hydroxy-3-nitrophenylacetyl-conjugated C
G; OTII, OVA-specific TCR transgenic; OX40ko, OX40 deficient; TNFRSF, TNFR superfamily; TNFSF, TNF superfamily. ![]()
Received for publication November 4, 2004. Accepted for publication January 18, 2005.
| References |
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+ cells that can differentiate to APC, NK cells, and follicular cells but not T or B cells. Immunity 7:493.[Medline]
- and
-chain genes under the control of heterologous regulatory elements. Immunol. Cell. Biol. 76:34.[Medline]
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