供体CD+4CD+25T细胞及调控基因FOXP3在急性移植物抗宿主病中的作用

目的 探讨供体CD+4CD+25T细胞亚群、FOXP3调控基因的表达与受者移植物抗宿主病(GVHD)的相关性.方法 (1)30例异基因造血干细胞移植(allo-HSCT),采用免疫荧光标记和流式细胞术检测并比较供体粒细胞集落刺激因子(G-CSF)动员前外周血、动员后采集物CD+4CD+25T细胞亚群比例,随访异基因移植后GVHD的发生率和严重程度.(2)应用RT-PCR技术检测供体FOXP3基因表达情况,分析其与GVHD、疾病复发的相关性.结果 (1)所有患者均获造血重建,粒细胞绝对数(ANC)≥0.5×109/L的中位时间为14(12～15)d,PLT≥20×109/L为18(15～25)d.30例allo-HSCT,中位随访时间12.8(8～16)个月,Ⅰ～Ⅳ度急性GVHD分别为3、4、3、5例.慢性GVHD 6例.(2)供体G-CSF动员前外周血、动员后采集物CD+4CD+25T细胞亚群分别为(2.67±0.38)%、(5.01±1.33)%,两者相比差异无统计学意义(P＞0.05).(3)移植后无急性GVHD组、Ⅰ～Ⅱ度急性GVHD组、Ⅲ～Ⅳ度急性GVHD组供体CD+4CD+25T细胞亚群分别为(5.05±1.34)%、(4.17±1.73)%、(1.98±1.10)%.其中Ⅰ～Ⅱ度急性GVHD组与Ⅲ～Ⅳ度急性GVHD组相比差异有统计学意义(P=0.04),无急性GVHD组与Ⅲ～Ⅳ度急性GVHD组相比差异有统计学意义(P=0.002).(4)30例allo-HSCT,7例FOXP3基因表达阳性,5/7例移植后无急性GVHD,其中3例移植后复发,另2/7例移植后Ⅰ度急性GVHD,Ⅱ～Ⅳ度急性GVHD患者FOXP3均不表达.结论 (1)供体CD+4CD+25T细胞亚群比例与受者急性GVHD的发生具有一定的相关性,提高供体CD+4CD+25T细胞数量有望减低移植后急性GVHD发生率.(2)供体移植物FOXP3基因表达阳性,与移植后有无严重急性GVHD发生存在一定相关性.     

CD4+CD25+调节性T细胞及其与移植物抗宿主病和移植物抗白血病的关系

CD4 CD25 调节性T细胞(Treg细胞)是CD4 T细胞的一个亚群,在维持机体自身免疫耐受,诱导移植耐受等方面发挥重要作用。移植物抗宿主病(GVHD)是异基因造血干细胞移植最严重的并发症之一。在动物骨髓移植模型中证实Treg细胞可以促进移植物植入,减少GVHD的发生率和严重度,但并没有消除移植物抗白血病(GVL)的作用。在人体有关Treg细胞对GVHD的影响因研究者分析Treg细胞采用的表型不同,其结论存在不一致性。本文就新近Treg细胞生物学特性,Treg细胞与GVHD和GVL的关系的研究进展进行综述。     

Paradoxical effects of interleukin-18 on the severity of acute graft-versus-host disease mediated by CD4+ and CD8+ T-cell subsets after experimental allogeneic bone marrow transplantation

Administration of exogenous interleukin-18 (IL-18) regulates experimental acute graft-versus-host disease (GVHD) in a Fas-dependent manner when donor CD4(+) T cells are required for mortality after experimental allogeneic bone marrow transplantation (BMT). However, CD4(+) and CD8(+) T cells can induce acute GVHD after clinical allogeneic BMT, and the role of IL-18 in CD8(+)-mediated acute GVHD is unknown. We, therefore, determined the role of IL-18 in GVHD mediated by CD4(+) or CD8(+) T cells across major histocompatibility complex (MHC) class II- and class I-disparate allogeneic BMT, respectively. Administering IL-18 significantly increased survival in CD4(+)-mediated GVHD but reduced survival in CD8(+)-mediated GVHD. This increase in deaths was associated with significantly greater clinical, biochemical, and histopathologic parameters of GVHD damage and was independent of Fas expression on donor T cells. Administering IL-18 significantly enhanced allospecific cytotoxic function and expansion of CD8(+) cells. Endogenous IL-18 was critical to GVHD mediated by CD8(+) donor T cells because IL-18 receptor-deficient donors caused significantly less GVHD but exacerbated CD4(+)-mediated, GVHD-related death. Furthermore, administering anti-IL-18 monoclonal antibody significantly reduced CD8(+)-mediated, GVHD-related death. Together these findings demonstrate that IL-18 has paradoxical effects on CD4(+) and CD8(+) cell-mediated GVHD.     

Absence of clinical GVHD and the in vivo induction of regulatory T cells after transplantation of facilitating cells

Graft-versus-host disease (GVHD) and failure of engraftment limit clinical bone marrow transplantation (BMT) to patients with closely matched donors. Engraftment failure of purified allogeneic hematopoietic stem cells (HSCs) has been decreased in various BMT models by including donor BM-derived CD8(+)/alphabetagammadeltaTCR(-) facilitating cells (FCs) or CD8(+)/alphabetaTCR(+) T cells in the BM inoculum. To aggressively investigate the GVHD potential of these donor CD8(+) populations, a purified cell model of lethal GVHD was established in a murine semiallogeneic parent --> F(1) combination. Lethally irradiated recipients were reconstituted with purified donor HSCs alone or in combination with splenic T cells (T(SP)), BM-derived T cells (T(BM)), or the FC population. In marked contrast to the lethal GVHD present in recipients of HSCs plus T(SP) or CD8(+) T(BM), recipients of donor HSC+FC inocula did not exhibit significant clinical or histologic evidence of GVHD. Instead, HSC+FC recipients were characterized by increased splenocyte expression of transforming growth factor-beta (TGF-beta) and the induction of the regulatory T-cell genes CTLA4, GITR, and FoxP3. These findings suggest that the FCs, which express a unique FCp33-TCRbeta heterodimer in place of alphabetaTCR, permits HSC alloengraftment and prevents GVHD through the novel approach of regulatory T-cell induction in vivo.     

Kinetic of regulatory CD25high and activated CD134+ (OX40) T lymphocytes during acute and chronic graft-versus-host disease after allogeneic bone marrow transplantation

Graft-versus-host disease (GVHD) is still a major complication after allogeneic stem cell transplantation. In murine models, freshly isolated or ex vivo expanded CD4(+)CD25(high) regulatory T cells (Treg) are able to ameliorate GVHD while maintaining graft-versus-leukaemia reactions. However, in the human setting, prospective studies of this population and its interaction with activated non-regulatory CD134(+) (OX40) lymphocytes during post-transplant follow-up are lacking. In this study, we prospectively quantified CD4(+)CD25(high) and activated CD134(+) lymphocytes in 119 peripheral blood samples from 35 consecutive patients who underwent allogeneic bone marrow transplantation (BMT). Fifty-five samples obtained less than 100 d after allogeneic BMT, were not statistically different regarding CD4(+)CD25(high) Treg or CD134(+) lymphocytes compared with those obtained from patients with (n = 35) or without (n = 20) acute GVHD. Chronic GVHD was associated with a small, but not statistically significant, increase in the number of Treg (9.9 vs. 6.7 x 10(6)/L). However, the CD134/CD25(high) ratio was significantly higher during chronic GVHD (cGHVD) when compared with either patients without cGVHD (67.7 +/- 40.3 vs. 4.0 +/- 0.9, P < 0.01) or cGVHD after treatment (67.7 +/- 40.3 vs. 3.7 +/- 0.8, P < 0.01). Our findings suggest that the suppressive activity of CD4(+)CD25(high) Treg could be abrogated in vivo during cGVHD by CD134 expression in a much higher number of activated donor T lymphocytes. In addition to CD4(+)CD25(high)ex vivo expansion protocols, OX40 blocking might be crucial to optimize the use of Treg to prevent GVHD.     

CD8+CD44(hi) but not CD4+CD44(hi) memory T cells mediate potent graft antilymphoma activity without GVHD

Allogeneic hematopoietic cell transplantation can be curative in patients with leukemia and lymphoma. However, progressive growth of malignant cells, relapse after transplantation, and graft-versus-host disease (GVHD) remain important problems. The goal of the current murine study was to select a freshly isolated donor T-cell subset for infusion that separates antilymphoma activity from GVHD, and to determine whether the selected subset could effectively prevent or treat progressive growth of a naturally occurring B-cell lymphoma (BCL(1)) without GVHD after recipients were given T cell-depleted bone marrow transplantations from major histocompatibility complex-mismatched donors. Lethal GVHD was observed when total T cells, naive CD4(+) T cells, or naive CD8(+) T cells were used. Memory CD4(+)CD44(hi) and CD8(+)CD44(hi) T cells containing both central and effector memory cells did not induce lethal GVHD, but only memory CD8(+) T cells had potent antilymphoma activity and promoted complete chimerism. Infusion of CD8(+) memory T cells after transplantation was able to eradicate the BCL(1) lymphoma even after progressive growth without inducing severe GVHD. In conclusion, the memory CD8(+) T-cell subset separated graft antilymphoma activity from GVHD more effectively than naive T cells, memory CD4(+) T cells, or memory total T cells.     

Donor CD8+ T cells facilitate induction of chimerism and tolerance without GVHD in autoimmune NOD mice conditioned with anti-CD3 mAb

Prevention of autoimmune diabetes and induction of islet transplantation tolerance in nonobese diabetic (NOD) mice can be reached by induction of mixed chimerism via bone marrow transplantation (BMT), but this procedure requires total body irradiation (TBI) conditioning of the recipients. The toxicity of radiation and potential for graft-versus-host disease (GVHD) prevents its clinical application. Donor CD8+ T cells play a critical role in facilitation of engraftment but also contribute to induction of GVHD in TBI-conditioned recipients. Here, we showed that high doses of donor CD8+ T cells in combination with bone marrow (BM) cells induced mixed chimerism without GVHD in NOD recipients conditioned with anti-CD3 monoclonal antibody (mAb). The prevention of GVHD in those recipients was associated with low-level production of inflammatory cytokines (ie, tumor necrosis factor alpha [TNF-alpha]), high-level production of anti-inflammatory cytokines (ie, interleukin 4 [IL-4] and IL-10), and confining of the donor CD8+ T-cell expansion to lymphohematopoietic tissues. The chimeric NOD recipients showed donor-specific tolerance and reversal of insulitis. These results demonstrate that donor CD8+ T-cell-mediated facilitation of engraftment can be separated from GVHD in nonirradiated recipients. This regimen may have potential application in the treatment of autoimmune disorders as well as induction of transplantation tolerance.     

CD25 expression on donor CD4+ or CD8+ T cells is associated with an increased risk for graft-versus-host disease after HLA-identical stem cell transplantation in humans

Graft-versus-host disease (GVHD) occurs in an unpredictable fashion after 30% to 50% of matched-related transplantations. The presence of increased frequencies of CD4(+)CD25(+) regulatory T cells in donor grafts has been shown to ameliorate GVHD after allogeneic transplantation in murine models. To determine whether a similar relationship exists in humans, we quantitated the coexpression of CD25 on CD4(+) and CD8(+) T cells within 60 donor grafts infused into matched siblings and examined GVHD incidence in the respective recipients. Recipients in whom GVHD developed received donor grafts containing significantly higher frequencies of CD4(+) T cells coexpressing CD25 than those who did not (median, 9.26% vs 2.22%; P =.004). Frequencies of donor graft CD8(+) T cells coexpressing CD25 were also higher (0.65% vs 0.14%; P =.002). Furthermore, transplant recipients who received grafts containing fewer CD4(+)CD25(+) and CD8(+)CD25(+) T cells were less likely to acquire acute GVHD, even though these donor-recipient pairs were similar to others with respect to relevant clinical variables. These data suggest that the coexpression of CD4 and CD25 may be insufficient to identify regulatory T cells in humans and that increased frequencies and numbers of CD25(+) T cells in donor grafts is associated with GVHD in transplant recipients.     

Effector memory CD4+ T cells mediate graft-versus-leukemia without inducing graft-versus-host disease

Much of the efficacy of allogeneic hematopoietic stem cell transplantation (alloSCT) in curing hematologic malignancies is due to a graft-versus-leukemia (GVL) effect mediated by donor T cells that recognize recipient alloantigens on leukemic cells. Donor T cells are also important for reconstituting immunity in the recipient. Unfortunately, donor T cells can attack nonmalignant host tissues and cause graft-versus-host disease (GVHD). We previously reported that donor CD4(+) effector memory T cells (T(EMs)) do not cause GVHD but transfer functional T-cell memory. In the present work, we demonstrate in an MHC-mismatched model that CD4(+) T(EMs) (unprimed to recipient antigens) mediate GVL against clinically relevant mouse models of chronic phase and blast crisis chronic myelogenous leukemia, without causing GVHD. By creating gene-deficient leukemias and using perforin-deficient T cells, we demonstrate that direct cytolytic function is essential for T(EM)-mediated GVL, but that GVL is retained when killing via FasL, TNF-alpha, TRAIL, and perforin is individually impaired. However, T(EM)-mediated GVL was diminished when both FasL and perforin pathways were blocked. Taken together, our studies identify T(EMs) as a clinically applicable cell therapy for promoting GVL and immune reconstitution, particularly in MHC-mismatched haploidentical alloSCTs in which T cell-depleted allografts are commonly used to minimize GVHD.     

L-Selectin(hi) but not the L-selectin(lo) CD4+25+ T-regulatory cells are potent inhibitors of GVHD and BM graft rejection

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality after bone marrow transplantation (BMT). CD4(+)CD25(+) immune regulatory T cells (Tregs), long recognized for their critical role in induction and maintenance of self-tolerance and prevention of autoimmunity, are also important in the regulation of immune responses in allogeneic bone marrow (BM) and solid organ transplantation. Published data indicate that ex vivo activated and expanded donor Tregs result in significant inhibition of lethal GVHD. This study provides a direct comparison of LSel(hi) and LSel(lo) Tregs for GVHD inhibition and for the promotion of allogeneic BM engraftment. Imaging of green fluorescent protein-positive effectors in GVHD control mice and LSel(hi) and LSel(lo) Treg-treated mice vividly illustrate the multisystemic nature of GVHD and the profound inhibition of GVHD by LSel(hi) Tregs. Data indicate that LSel(hi) Tregs interfere with the activation and expansion of GVHD effector T cells in secondary lymphoid organs early after BMT. Either donor- or host-type LSel(hi), but not LSel(lo), Tregs potently increased donor BM engraftment in sublethally irradiated mice, an event occurring independently of transforming growth factor beta signaling of host T cells. These data indicate that Treg cellular therapy warrants clinical consideration for the inhibition of GVHD and the promotion of alloengraftment.     

Larger numbers of CD4(bright) dendritic cells in donor bone marrow are associated with increased relapse after allogeneic bone marrow transplantation

Relapse is the major cause of death after allogeneic bone marrow transplantation (BMT). This study tested the hypothesis that the numbers of donor mononuclear cells, lymphocytes, and CD34(+) cells influence relapse and event-free survival (EFS) after BMT. The study population consisted of 113 consecutive patients with hematologic malignancies who underwent non-T-cell-depleted BMT from HLA-matched siblings. Sixty-four patients had low-risk diagnoses (ALL/AML CR1, MDS RA/RARS, and CML CP1); 49 patients had high-risk diagnoses (all others). CD34(+) cells, T cells, B cells, natural killer cells, monocytes, and a rare population of CD3(-), CD4(bright) cells in the allografts were measured by flow cytometry. The CD3(-), CD4(bright) cells in bone marrow had the same frequency and phenotype as CD123(bright) type 2 dendritic cell (DC) progenitors, and they differentiated into typical DCs after short-term culture. Cox regression analyses evaluated risk strata, age, gender, and the numbers of nucleated cells, CD3(+) T cells, CD34(+) hematopoietic cells, and CD4(bright) cells as covariates for EFS, relapse, and nonrelapse mortality. Recipients of larger numbers of CD4(bright) cells had significantly lower EFS, a lower incidence of chronic graft-versus-host disease (cGVHD), and an increased incidence of relapse. Recipients of larger numbers of CD34(+) cells had improved EFS; recipients of fewer CD34(+) cells had delayed hematopoietic engraftment and increased death from infections. In conclusion, the content of donor CD4(bright) cells was associated with decreased cGVHD and graft-versus-leukemia effects in recipients of allogeneic bone marrow transplantation, consistent with a role for donor DCs in determining immune responses after allogeneic BMT.     

Engraftment of DLA-haploidentical marrow with ex vivo expanded, retrovirally transduced cytotoxic T lymphocytes.

Genetically modified donor T cells with an inducible "suicide" gene have the potential to improve the safety and availability of allogeneic hematopoietic stem cell transplantation by enhancing engraftment and permitting control of graft-versus-host disease (GVHD). However, several clinical studies of gene-modified T cells have shown limited to no in vivo function of the ex vivo expanded T cells. Using the well-established dog model of allogeneic marrow transplantation, the question was asked if retrovirally transduced, donor derived, ex vivo expanded cytotoxic T lymphocytes (CTLs) that are recipient specific could enhance engraftment of dog leukocyte antigen (DLA)-haploidentical marrow following a single dose of 9.2 Gy total body irradiation and no postgrafting immunosuppression. In this setting, only 4 of 11 control recipients of DLA-haploidentical marrow without added CTLs engrafted. CTLs did not enhance engraftment of CD34(+) selected peripheral blood stem cells. However, recipient-specific CTLs enhanced engraftment of DLA-haploidentical marrow in 9 of 11 evaluable recipients (P =.049). All dogs that engrafted developed multiorgan GVHD. To facilitate in vivo tracking, 8 dogs received CTLs transduced with a retroviral vector encoding green fluorescent protein (GFP) and neomycin phosphotransferase (neo). Recipients that engrafted had sharp increases in the numbers of circulating GFP(+) CTLs on days +5 to +6 after transplantation. GFP(+) CTLs isolated from blood were capable of recipient-specific lysis. At necropsy, up to 7.1% of CD3(+) cells in tissues were GFP(+) and polymerase chain reaction in situ hybridization for neo showed infiltration of transduced CTLs in GVHD-affected organs. These results show that ex vivo expanded, transduced T cells maintained in vivo function and enhanced marrow engraftment.     

Tolerance induction by third-party "off-the-shelf" CD4+CD25+ Treg cells

OBJECTIVE: Recent reports have shown that donor or host CD4(+)CD25(+) Treg cells can be used to control GVHD or graft rejection following allogeneic BMT in mice. In the present study we investigated the potential of third-party Treg cells compared to donor-type cells to facilitate BM allografting. METHODS: Graft rejection is assessed in a mouse model of T cell-mediated BM allograft rejection. Lethally irradiated C3H mice are transplanted at day 2 after irradiation with T cell-depleted Balb/Nude BM. Graft rejection is induced by purified host-type T cells infused one day prior to BMT. Cells tested for their facilitating activity are added to the T cell-depleted BM allograft. RESULTS: Na?ve or ex vivo-expanded third-party Treg cells can effectively enhance engraftment of T cell-depleted BM allografts, exhibiting reactivity in vitro and in vivo similar to that found for donor-type Treg cells. CONCLUSION: The use of third-party Treg cells in contrast to donor-type cells could allow advanced preparation of a large bank of Treg cells (off-the-shelf), with all the appropriate quality controls required for cell therapy.     

CD62L- memory T cells enhance T-cell regeneration after allogeneic stem cell transplantation by eliminating host resistance in mice

A major challenge in allogeneic hematopoietic cell transplantation is how to transfer T-cell immunity without causing graft-versus-host disease (GVHD). Effector memory T cells (CD62L(-)) are a cell subset that can potentially address this challenge because they do not induce GVHD. Here, we investigated how CD62L(-) T cells contributed to phenotypic and functional T-cell reconstitution after transplantation. On transfer into allogeneic recipients, CD62L(-) T cells were activated and expressed multiple cytokines and cytotoxic molecules. CD62L(-) T cells were able to deplete host radioresistant T cells and facilitate hematopoietic engraftment, resulting in enhanced de novo T-cell regeneration. Enhanced functional immune reconstitution was demonstrated in CD62L(-) T-cell recipients using a tumor and an influenza virus challenge model. Even though CD62L(-) T cells are able to respond to alloantigens and deplete host radioresistant immune cells in GVHD recipients, alloreactive CD62L(-) T cells lost the reactivity over time and were eventually tolerant to alloantigens as a result of prolonged antigen exposure, suggesting a mechanism by which CD62L(-) T cells were able to eliminate host resistance without causing GVHD. These data further highlight the unique characteristics of CD62L(-) T cells and their potential applications in clinical hematopoietic cell transplantation.     

Blockade of osteopontin reduces alloreactive CD8+ T cell-mediated graft-versus-host disease

Graft-versus-host disease (GVHD), a life-threatening complication after allogeneic hematopoietic stem cell transplantation, is caused by alloreactive donor T cells that trigger host tissue damage. The inflammatory environment inside recipients is critical for GVHD pathogenesis, but the underpinning mechanisms remain elusive. Using mouse model of human GVHD, we demonstrate osteopontin (OPN), a potent proinflammatory cytokine, plays an important role in regulating activation, migration, and survival of alloreactive T cells during GVHD. OPN was significantly elevated after irradiation and persisted throughout the course of GVHD. Blockade of OPN attenuated GVHD with reduced accumulation of donor T cells in recipient organs. Amelioration was the result of migration and survival suppression caused by anti-OPN treatment on donor-derived T cells for 2 reasons. First, OPN promoted the migration and infiltration of naive and alloreactive CD8(+) T cells into host organs. Second, it also facilitated activation and viability of donor-derived CD8(+) T cells via synergizing with T-cell receptor/CD3 signaling. Finally, anti-OPN treatment retained graft-versus-leukemia effect of alloreactive CD8(+) T cells. This study demonstrates, to our knowledge for the first time, the critical effect of OPN in the initiation and persistence of CD8(+) T cell-mediated GVHD and validates OPN as a potential target in GVHD prevention.     

Differential use of Fas ligand and perforin cytotoxic pathways by donor T cells in graft-versus-host disease and graft-versus-leukemia effect

In allogeneic bone marrow transplantation (BMT) donor T cells are primarily responsible for antihost activity, resulting in graft-versus-host disease (GVHD), and for antileukemia activity, resulting in the graft-versus-leukemia (GVL) effect. The relative contributions of the Fas ligand (FasL) and perforin cytotoxic pathways in GVHD and GVL activity were studied by using FasL-defective or perforin-deficient donor T cells in murine parent --> F1 models for allogeneic bone marrow transplantation. It was found that FasL-defective B6.gld donor T cells display diminished GVHD activity but have intact GVL activity. In contrast, perforin-deficient B6.pfp(-/-) donor T cells have intact GVHD activity but display diminished GVL activity. Splenic T cells from recipients of B6.gld or B6.pfp(-/-) T cells had identical proliferative and cytokine responses to host antigens; however, splenic T cells from recipients of B6.pfp(-/-) T cells had no cytolytic activity against leukemia cells in a cytotoxicity assay. In experiments with selected CD4(+) or CD8(+) donor T cells, the FasL pathway was important for GVHD activity by both CD4(+) and CD8(+) T cells, whereas the perforin pathway was required for CD8-mediated GVL activity. These data demonstrate in a murine model for allogeneic bone marrow transplantation that donor T cells mediate GVHD activity primarily through the FasL effector pathway and GVL activity through the perforin pathway. This suggests that donor T cells make differential use of cytolytic pathways and that the specific blockade of one cytotoxic pathway may be used to prevent GVHD without interfering with GVL activity.     

Role of CXCR3-induced donor T-cell migration in acute GVHD

OBJECTIVE: The chemokine receptor CXCR3 has an important role in the migration of effector T cells. To investigate the role of CXCR3 on donor cells in acute graft vs host disease (GVHD) we used a well-defined experimental bone marrow transplantation (BMT) model where acute GVHD is mediated by donor CD8(+) T cells against minor histocompatibility antigens. METHODS; Lethally irradiated C3H.SW recipients were transplanted from either wild-type B6 or CXCR3(-/-) B6 donors. Donor T-cell expansion was analyzed in the spleen and small intestine of recipients by FACS. Donor T-cell function was analyzed by cytokine secretion. The severity of acute GVHD was assessed by histopathological analysis of intestine and liver, GVHD clinical scores, and survival after BMT. RESULTS: Significantly higher numbers of donor CD8(+) CXCR3(-/-) T cells were found in the spleen on days +7 and +14 compared to donor wild-type T cells. By contrast, the number of CD8(+) T cells in the small bowel of BMT recipients from CXCR3(-/-) donors was sevenfold lower than from wild-type donors. Systemic concentrations of INF-gamma and TNF-alpha were equivalent between groups. Animals that received CXCR3(-/-) donor T cells demonstrated diminished GI tract and liver damage and showed improved survival after BMT compared to recipients of wild-type donor cells (43% vs 0%, p<0.001). CONCLUSION: The migration of donor CD8(+) T cells to GVHD target organs such as the intestine depends on the expression of CXCR3 and contributes significantly to GVHD damage and overall mortality.     

Lymphopenia-induced proliferation of donor T cells reduces their capacity for causing acute graft-versus-host disease

OBJECTIVE: T cells that undergo lymphopenia-induced proliferation (LIP) are characterized by greater effector and anti-tumor function than na?ve T cells. But the ability of these T cells in causing graft-versus-host disease (GVHD) is not known. METHODS: We tested the hypothesis that donor T cells that had undergone LIP would cause more severe GVHD than na?ve T cells by utilizing well-characterized murine experimental models of allogeneic bone marrow transplantation (BMT). RESULTS: Contrary to our hypothesis, LIP of donor T cells under either noninflammatory or irradiated conditions caused significantly reduced GVHD as determined by survival, clinical, pathologic, and biochemical parameters than na?ve T cells. Compared to na?ve donor T cells, LIP T cells demonstrated reduced expansion in vivo and in vitro after allogeneic BMT. The reduction in GVHD mortality and severity was observed across multiple strains after allogeneic BMT. In vivo mechanistic studies by cell depletion demonstrated an increase in the CD44(hi) "memory" phenotype T cells and not the CD4(+)CD25(+) T cell subset to be critical for the reduction in GVHD. CONCLUSIONS: These data demonstrate that LIP of T cells regulates acute GVHD severity in contrast to their ability to cause increased allograft rejection, autoimmunity, or anti-tumor immunity.     

Rapidly proliferating CD44hi peripheral T cells undergo apoptosis and delay posttransplantation T-cell reconstitution after allogeneic bone marrow transplantation

Delayed T-cell recovery is an important complication of allogeneic bone marrow transplantation (BMT). We demonstrate in murine models that donor BM-derived T cells display increased apoptosis in recipients of allogeneic BMT with or without GVHD. Although this apoptosis was associated with a loss of Bcl-2 and Bcl-X(L) expression, allogeneic recipients of donor BM deficient in Fas-, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)- or Bax-, or BM-overexpressing Bcl-2 or Akt showed no decrease in apoptosis of peripheral donor-derived T cells. CD44 expression was associated with an increased percentage of BM-derived apoptotic CD4(+) and CD8(+) T cells. Transplantation of RAG-2-eGFP-transgenic BM revealed that proliferating eGFP(lo)CD44(hi) donor BM-derived mature T cells were more likely to undergo to apoptosis than nondivided eGFP(hi)CD44(lo) recent thymic emigrants in the periphery. Finally, experiments using carboxyfluorescein succinimidyl ester-labeled T cells adoptively transferred into irradiated syngeneic hosts revealed that rapid spontaneous proliferation (as opposed to slow homeostatic proliferation) and acquisition of a CD44(hi) phenotype was associated with increased apoptosis in T cells. We conclude that apoptosis of newly generated donor-derived peripheral T cells after an allogeneic BMT contributes to delayed T-cell reconstitution and is associated with CD44 expression and rapid spontaneous proliferation by donor BM-derived T cells.     

Administration of interleukin-7 after allogeneic bone marrow transplantation improves immune reconstitution without aggravating graft-versus-host disease

Prolonged immunodeficiency after allogeneic bone marrow transplantation (BMT) causes significant morbidity and mortality from infection. This study examined in murine models the effects of interleukin-7 (IL-7) given to young and middle-aged (9-month-old) recipients of major histocompatibility complex (MHC)-matched or -mismatched allogeneic BMT. Although administration of IL-7 from day 0 to 14 after syngeneic BMT promoted lymphoid reconstitution, this regimen was ineffective after allogeneic BMT. However, IL-7 administration from day 14 (or 21) to 27 after allogeneic BMT accelerated restoration of the major lymphoid cell populations even in middle-aged recipients. This regimen significantly expanded donor-derived thymocytes and peripheral T cells, B-lineage cells in bone marrow and spleen, splenic natural killer (NK) cells, NK T cells, and monocytes and macrophages. Interestingly, although recipients treated with IL-7 had significant increases in CD4(+) and CD8(+) memory T-cell populations, increases in naive T cells were less profound. Most notable, however, were the observations that IL-7 treatment did not exacerbate graft-versus-host disease (GVHD) in recipients of an MHC-matched BMT, and would ameliorate GVHD in recipients of a MHC-mismatched BMT. Nonetheless, graft-versus-leukemia (GVL) activity (measured against 32Dp210 leukemia) remained intact. Although activated and memory CD4(+) and CD8(+) T cells normally express high levels of IL-7 receptor (IL-7R, CD127), activated and memory alloreactive donor-derived T cells from recipients of allogeneic BMT expressed little IL-7R. This might explain the failure of IL-7 administration to exacerbate GVHD. In conclusion, posttransplant IL-7 administration to recipients of an allogeneic BMT enhances lymphoid reconstitution without aggravating GVHD while preserving GVL.