In vitro analysis of age-related changes in the developmental potential of bone marrow thymocyte progenitors

Mechanisms underlying the age-related decrease in the developmental capacity of thymocyte progenitors from the bone marrow (BM) were analyzed, focussing on interaction of these cells with the thymic microenvironment. We employed the experimental model in which mixtures of young and old mouse BM cells, congenic for the Thy-1 marker, were seeded onto fetal thymus (FT) explains depleted of self lymphocytes and the levels of Thy-1+ cells developing from each of the two donor types were measured. When cells from young and old BM donors were seeded simultaneously, in saturating quantities, a higher level of T cells developed from the young donors. To find out whether there were originally more thymocyte progenitors in the young BM, we carried out the competitive colonization under limiting dilution conditions and found that the advantage of the young had diminished under these conditions, thus suggesting that the age-related changes could not be related solely to quantitative differences. We then incubated the FT sequentially with old donor cells for 24 h, followed by young for an additional 48 h and found that the advantage of the young progenitors was eliminated. We thus established that the initial stage of colonization of the FT was important in determining the outcome of the subsequent development. The kinetics of simultaneous competition within the FT, however, revealed that the advantage of the young BM-derived cells became significant only from day 7 in organ culture, thus suggesting that sequential divisions of these cells were at a higher level than those of the old. Recolonization of FT explants by young or old BM-derived thymocytes obtained from the first colonization of the FT stroma showed a reduced, but still significant advantage for the young BM-derived cells over the old. Thus, we concluded that the old BM thymocyte progenitors manifested a qualitative disadvantage which became apparent during competitive colonization of the FT.     

Functional studies on T cells in adult human bone marrow.

Bone marrow (BM) lymphocytes were obtained by sucrose density gradient centrifugation of the nucleated cells from adult human BM. BM was obtained from rib sections removed routinely during thoracotomy from thirteen patients with a localized lung tumour and from two other patients without tumour (mean age 47 years). The percentage of T cells in BM was high (mean +/- s.d. 27% +/- 17) and increased with age. In eight cases, the function of isolated BM T cells was studied and compared to that of peripheral blood (PB) T cells. BM t cells showed poor helper activity for pokeweed mitogen (PWM) induced Ig production by PB non-T cells, which did not appear to be due to excessive suppressor cell activity. Phytohaemagglutinin (PHA) induced thymidine incorporation was only slightly decreased but peak values were only reached after 6 years, in contrast to 4 days for PB T cells. This delay did not seem to be due to a lack of monocytes. PHA, however, failed to induce cytotoxic activity in BM T cells. PWM-induced thymidine incorporation and responder capacity in the mixed lymphocyte reaction were also very poor. These results are interpreted as suggesting that many of the T cells in adult human marrow are immature.     

Irreversible inactivation of activated cytotoxic T lymphocyte precursor cells by "anti-self" suppressor cells present in murine bone marrow T cell colonies

When added to a mixed lymphocyte culture, cells in T cell colonies grown from bone marrow (BM) suppressed the development of cytotoxic activity against H-2 antigens shared by the colony cells and the stimulator cells, apparently by inactivating cytotoxic T lymphocyte precursor cells (CTLP). From the point of view of the added suppressor cells, the suppression was against self-reactive cells. The suppressor cells were resistant to gamma irradiation (1500 rds) but sensitive to UV irradiation. Inactivated CTLP separated from the suppressor cells by cell sorting could not be reactivated on being recultured with fresh stimulator cells, suggesting the suppression is irreversible. There was a critical time window, extending roughly from 20 to 40 h after culture initiation, during which the suppressor cell had to be present if CTLP were to be inactivated. During the first 20 h and after 40 h of exposure to stimulator cells, CTLP were resistant to the suppressor cell. Direct experimental evidence is presented against the possibility that the suppressor cells derived from BM colonies act by augmenting the production of Lyt-2+ suppressor cells from the responder population which then produce the suppression, or that the suppressor cells interfere with an early interaction between CTLP and stimulator cells. We conclude that the suppressor cells in T cell colonies grown from BM act directly on activated CTLP and permanently inactivate them.     

Committed precursors of B and T lymphocytes in chick embryo bursa of Fabricius, thymus, and bone marrow

Lymphocyte precursors in bursa of Fabricius, thymus and bone marrow (BM) of chick embryos were studied at different stages of incubation over 12-21 days, and for their state of commitment to B or T cell lines of development. Cell suspensions were fractionated on albumin gradients to remove nonlymphoid cells and incubated in vitro with bursopoietin, a specific inducer of B cells, or crude chicken thymus extract, a specific inducer of T cells, or ubiquitin, a nonspecific inducer. Precursors were identified by increases in numbers of cells bearing surface alloantigens as determined by immunofluorescence, either Bu-1 (specific to B cells) or Th-1 (specific to T cells). Precursors inducible to Bu-1+ cells were found in bursal cells and BM cells from all age groups but not in thymic cells. Precursors inducible to Th-1+ cells were found in thymic preparations and BM cells at all ages, but in significant numbers in bursa on day 12 only. Because B and T precursors were never found together in bursa or thymus, or only in very unequal amounts, it was concluded that precursors in these organs were not multipotential but were separately committed to one or other line of development. This argument did not apply to BM cells, for which other evidence was obtained. Bu-1+ cells were specifically induced in BM cells with bursopoietin and then removed by complement-dependent cytolysis wih anti-Bu-1 antiserum. When the remaining cells were incubated with ubiquitin, only Th-1+ cells were induced, showing that Bu-1 and Th-1 precursors were separately committed. Surface IgM was never induced on either bursal or BM lymphocytes. The Ia (or B-L) antigen was inducible on 12- to 21-day bursal cells, but could not be generated on BM cells until day 14 onwards. The pattern of occurrence of committed lymphocyte precursors in the developing chick embryo suggests that these cells are released into the circulation from both central lymphoid organs at their respective times of high lymphopoietic activity, and accumulate in the BM at least up to the time of hatching. Moreover, the presence of committed B precursors in bursa and committed T precursors in thymus at times and in quantities appropriate to the known features of avian lymphopoiesis leads us to conclude that in vitro induction is analogous to a true stage of in vivo B and T cell differentiation.     

Severe combined immunodeficiency in man with an absence of immunoglobulin gene rearrangements but normal T cell receptor assembly

An autosomal recessive type of severe combined immunodeficiency disease (SCID) was characterized by an absence of immunoglobulins (Ig) in the serum and of Ig+ lymphocytes in bone barrow (BM) and peripheral blood. In the BM CD10+/terminal deoxynucleotidyl transferase-positive lymphocytes were identified. Epstein-Barr virus-transformed B lymphoblastoid cell lines (BLCL) obtained from BM and peripheral blood did not synthesize Ig. The Ig heavy and light chain gene complexes in the BLCL had retained the germ-line configuration. Mature T cells were present but their numbers in peripheral blood were decreased. T lymphoblastoid cells derived from peripheral blood expressed normal T cell receptor (TcR) CD3 complexes and manifested various genomic TcR rearrangements. It was concluded that this type of SCID entailed a complete arrest of B lymphocyte differentiation in an early stage prior to Ig rearrangements and a quantitative defect of T lymphocytes which nevertheless allowed development of mature T cells. Repeated failures of BM transplantation and the striking absence of Ig assembly suggested that this SCID defect resides in the BM microenvironment.     

脐带血的T淋巴细胞集落培养

本文应用细胞培养和免疫间接荧光法测定脐血，正常人体外周血和成人骨髓的Ｔ淋巴细胞集落形成情况及培养前后淋巴细胞亚群的变化，结果表明：脐血的ＣＦｕ－ＴＬ显著低于正常人外周血（Ｐ〈０．０１），略低于成人骨髓（Ｐ〉０．０５）培养脐血的ＣＤ３，ＣＤ４细胞含量均显著低于正常人外周血（Ｐ〈０．０１），与成人骨髓相近似（Ｐ〉０．０５）脐血的ＣＤ８细胞含量与正常人外周血和成人骨髓相似（Ｐ〉０．０５）；培养后的ＣＦｕ     

Normal serum immunoglobulins influence the numbers of bone marrow pre-B and B cells.

The homeostatic mechanisms controlling B lymphocyte output from bone marrow are not well understood. The present experiments evaluated putative influences of circulating immunoglobulins (Ig) on bone marrow (BM) pre-B and B cell populations. Injections into normal mice of Ig isolated from normal mouse serum, resulted in a dose-dependent and reversible reduction in numbers of BM B lineage cells, in particular of small B220+ surface IgM- cells. Maximal effects were observed upon injection of isologous polyclonal Ig and were independent of mature T cells. These results suggest a feedback modulation of peripheral Ig on cellular activities in BM B lineage compartments, mediated by mechanisms that seem to involve the variable regions of the Ig molecule.     

Expression of CTLA-4 and FOXP3 in cis protects from lethal lymphoproliferative disease

Both CTLA-4-deficient and FoxP3-deficient mice exhibit a short life span due to massive lymphoproliferation (LP) and a systemic autoimmune-like syndrome. Although it has been postulated that both diseases result from regulatory T cell (T(reg)) defects, there have been no direct complementation studies to elucidate their relationship in homeostatic lymphocyte proliferation during the neonatal period. In this study, reconstitution of sublethally irradiated RAG KO mice with either CTLA-4-deficient or FoxP3-deficient bone marrow (BM) resulted in LP disease similar to that observed in CTLA-4 KO or Scurfy mice, respectively. Although co-injection of BM from wild-type mice inhibited the activation of CTLA-4-deficient or FoxP3-deficient T cells and ameliorated LP disease through extrinsic regulatory mechanisms by T(reg) cells, mice that had received the BM mixture of Scurfy and CTLA-4 KO BM eventually died of incomplete protection. These results suggest common attributes of both diseases, but expression of both CTLA-4 and FoxP3 on the same cell subset is essential to fully prevent LP disease.     

Homing Characteristics of Donor T Cells after Experimental Allogeneic Bone Marrow Transplantation and Posttransplantation Therapy for Multiple Myeloma

Relapse and graft-versus-host disease remain major problems associated with allogeneic bone marrow (BM) transplantation (allo-BMT) and posttransplantation therapy in patients with multiple myeloma (MM) and other hematologic malignancies. A possible strategy for selectively enhancing the graft-versus-myeloma response and possibly reducing graft-versus-host disease is to increase the migration of alloreactive T cells toward the MM-containing BM. In the present study, we characterized the BM-homing behavior of donor-derived effector T cells in a novel allo-BMT model for the treatment of MM. We observed that posttransplantation immunotherapy consisting of donor lymphocyte infusion (DLI) and vaccination with minor histocompatibility antigen-loaded dendritic cells (DCs) was associated with prolonged survival compared with allo-BMT with no further treatment. Moreover, CD8⁺ effector T cells expressing inflammatory homing receptors, including high levels of CD44, LFA-1, and inflammatory chemokine receptors, were recruited to MM-bearing BM. This was paralleled by strongly increased expression of IFN-γ and IFN-γ–inducible chemokines, including CXCL9, CXCL10, and CXCL16, especially in mice treated with DLI plus minor histocompatibility antigen-loaded DC vaccination. Remarkably, expression of the homeostatic chemokine CXCL12 was reduced. Furthermore, IFN-γ and TNF-α induced BM endothelial cells to express high levels of the inflammatory chemokines and reduced or unaltered levels of CXCL12. Finally, presentation of CXCL9 by multiple BM endothelial cell-expressed heparan sulfate proteoglycans triggered transendothelial migration of effector T cells. Taken together, our data demonstrate that both post-transplantation DLI plus miHA-loaded DC vaccination and MM growth result in an increased expression of inflammatory homing receptors on donor T cells, decreased levels of the homeostatic BM-homing chemokine CXCL12, and strong induction of inflammatory chemokines in the BM. Thus, along with increasing the population of alloreactive T cells, post-transplantation immunotherapy also might contribute to a more effective graft-versus-tumor response by switching homeostatic T cell migration to inflammation-driven migration.     

Prevention of graft-versus-host disease by intrabone marrow injection of donor T cells: involvement of bone marrow stromal cells

We have developed a new and effective method for bone marrow transplantation (BMT): bone marrow cells (BMCs) are injected directly into the bone marrow (BM) cavity of recipient mice. The intrabone marrow injection of BMCs (IBM-BMT) greatly facilitates the engraftment of donor-derived cells, and IBM-BMT can attenuate graft-versus-host reaction (GVHR), in contrast to conventional intravenous BMT (i.v.-BMT). Here, we examine the mechanisms underlying the inhibitory effects of IBM-BMT on GVHR using animal models where GVHR is elicited. Recipient mice (C57BL/6) were irradiated and splenic T cells (as donor lymphocyte infusion: DLI) from major histocompatibility complex-disparate donors (BALB/c) were injected directly into the BM cavity (IBM-DLI) or injected intravenously (i.v.-DLI) along with IBM-BMT. The BM stromal cells (BMSCs) from these recipients were collected and related cytokines were examined. The recipient mice that had been treated with IBM-BMT + i.v.-DLI showed severe graft-versus-host disease (GVHD), in contrast to those treated with IBM-BMT + IBM-DLI. The suppressive activity of BMSCs in this GVHD model was determined. The cultured BMSCs from the recipients treated with IBM-BMT + IBM-DLI suppressed the proliferation of responder T cells remarkably when compared with those from the recipients of IBM-BMT + i.v.-DLI in mixed leucocyte reaction. Furthermore, the level of transforming growth factor-beta and hepatocyte growth factor in cultured BMSCs from IBM-BMT + IBM-DLI increased significantly when compared with those from the recipients of IBM-BMT + i.v.-DLI. Thus, the prevention of GVHD observed in the recipients of IBM-BMT + IBM-DLI was attributable to the increased production of immunosuppressive cytokines from BMSCs after interaction with host reactive T cells (in DLI).     

CD28/B7信号在再生障碍性贫血T淋巴细胞异常活化中的作用

目的 通过淋巴细胞输注诱导自身免疫性再生障碍性贫血动物模型,探讨CD28/B7信号在淋巴细胞异常活化中的作用及可能机制.方法 将来自父本的淋巴细胞悬液(40×106个几左右)通过尾静脉注入CBYB6 F1代受鼠体内,采用CFDA-SE标记法跟踪淋巴细胞在体内的分布,尾静脉注射CD80和CD86阻断性单克隆抗体(单抗),不同时段检测受体小鼠外周血象的变化,病理切片观察骨髓及主要脏器的变化.将骨髓造血细胞与淋巴结淋巴细胞进行共培养,通过计数造血细胞的集落形成数来观察不同数量淋巴结淋巴细胞对骨髓造血细胞的影响.体外测试不同浓度环孢菌素A(cyclosporine A,CsA)对骨髓造血细胞的影响.结果 输注淋巴细胞后可诱导受体小鼠在第5天出现骨髓衰竭的表现,主要是白细胞、血红蛋白、血小板下降,21 d左右受体鼠出现死亡.不同时间段受体小鼠主要脏器冰冻切片显示荧光标记的淋巴细胞主要分布在骨髓组织中;病理切片显示有骨髓组织的破坏.同时注射CD80及CD86阻断性单抗的受体鼠同样出现上述表现;体外集落形成试验证实B6淋巴结淋巴细胞数量和F1造血细胞为5:1时,红系集落形成单位(CFU-E)和粒细胞集落形成单位(CFU-G)集落形成数目与空白组比较差异无统计学意义(P>0.05);将比例提高至10:1,CFU-E集落形成数目明显减少(P<0.05);至50:1时,则可完全抑制CFU-E集落的形成,CFU-E和CFU-G集落形成数日的减少呈现淋巴细胞剂量依赖性,加入CsA可显著提高CFU-E和CFU-G形成率.结论 通过模型证实T细胞在再生障碍性贫血的发生过程中起重要作用,仅通过阻断CD28/B7信号并不能阻断T淋巴细胞的异常活化.     

Soybean agglutinin-positive natural suppressor cells in mouse bone marrow inhibit interleukin 2 production and utilization in mixed lymphocyte reactions.

Although natural suppressor (NS) cells resident in bone marrow (BM) have been the subject of intensive study, the exact nature and mode of action of these potentially important immunoregulatory cells are still uncertain. Here we show that NS cells with potent inhibitory effects on mixed lymphocyte reactions (MLRs) can be isolated from BM of normal adult mice by agglutination with the plant lectin soybean agglutinin (SBA). Complement-dependent lysis of SBA receptor-bearing BM cells with antibodies to asialoGM1, Mac-1, Thy-1.2, J11d.2, and 2C1 phenotypic markers reveals the presence of at least two distinct populations of BM NS cells. Most of the SBA-binding BM cells with NS capacity have the null phenotype and resemble hematopoietic stem cells, and some inhibitory SBA+ BM cells express the 2C1 marker found on pregnancy-associated splenic NS cells and the J11d.2 antigen characteristic of B cells and immature T cells. Results of positive selective experiments confirmed these findings. The mechanism of natural suppression was also studied. Evidence is presented that SBA+ BM cells exert NS activity in MLRs by interfering with the production and utilization of interleukin 2. Indomethacin does not relieve natural suppression associated with SBA+ BM cells, indicating that prostaglandin synthesis is not a requirement for inhibitory function. However, neutralizing antibodies to transforming growth factor beta (TGF-beta) partially reverse the suppression mediated by SBA+ BM cells, suggesting that some BM NS cells may act through the release of an immunosuppressive molecule related to TGF beta.     

人源化NOD/SCID小鼠免疫细胞的动态变化与鉴定

目的： 比较脐血干细胞与单个核细胞移植NOD/SCID鼠所建立的人源化SCID模型，分析人源化淋巴细胞重建。方法： 磁珠分选法分离脐血中CD34⁺细胞，淋巴细胞分层液分离脐血单个核细胞，分别经尾静脉输入NOD/SCID小鼠。每隔2周采血至10周，流式细胞术动态检测人源淋巴细胞CD45、CD19、CD3抗原。第10周处死小鼠收集外周血、骨髓、胸腺组织，RT-PCR检测模型鼠组织中人β₂M基因及RAG2基因。结果： 两种类型细胞移植均可重建人源免疫细胞，人源淋巴细胞表达水平均在第8周达高峰。骨髓中人源淋巴细胞表达水平明显高于外周血。RT-PCR在外周血与骨髓检测到人β₂M基因及RAG2基因标志。结论： CD34⁺细胞移植重建人源化NOD/SCID免疫系统模型效果要好于脐血单个核细胞。人源T淋巴细胞在模型鼠骨髓中分化成熟。     

Enrichment of IL-12–Producing Plasmacytoid Dendritic Cells in Donor Bone Marrow Grafts Enhances Graft-versus-Leukemia Activity in Allogeneic Hematopoietic Stem Cell Transplantation

A critical question in the field of allogeneic hematopoietic stem cell transplantation (HSCT) is how to enhance graft-versus-leukemia (GVL) activity while limiting graft-versus-host-disease (GVHD). We have previously reported that donor bone marrow (BM) precursors of plasmacytoid dendritic cells (pre-pDCs) can polarize donor T cells toward Th1 immunity and augment the GVL activity of donor T cells while attenuating their GVHD activity in a murine model of allogeneic HSCT. Clinical data on the role of donor pre-pDCs and conventional DCs (cDCs) on transplantation outcomes has been conflicting. To test the effect of increasing the proportion of pre-pDCs versus cDCs in a BM graft, we enriched CD11b⁻ pDCs by selectively depleting the CD11b⁺ myeloid DC (mDC) population from BM using FACS sorting in a murine model of allogeneic BM transplantation. Donor T cell expansion and GVL activity were greater in mice that received BM depleted of mDCs compared with mice that received undepleted BM. GVHD was not increased by depleting mDCs. To examine the mechanism through which mDC depletion enhances the GVL activity of donor T cells, we used BM and pDCs from IL-12p40KO mice, and found that the increased GVL activity of mDC-depleted BM was IL-12–dependent. This study indicates that a clinically translatable strategy of engineering the DC content of grafts can improve clinical outcomes in allogeneic HSCT through the regulation of donor T cell activation and GVL activity.     

The role of human alveolar macrophages in the allogeneic and autologous mixed leucocyte reactions.

Human alveolar macrophages (AM) are deficient in their ability to promote antigen-stimulated lymphocyte proliferation when compared to in-vitro-aged blood derived macrophages (BM). The mechanisms behind the unique accessory cell function of human AM are unknown. The current paradigm for accessory cell function requires antigen presentation in the context of gene products of the HLA-DR locus of the major histocompatibility complex (Class II, DR antigens) and secretion of non-specific second signal (e.g. interleukin 1). While both AM and in-vitro-aged BM have limited ability to secrete interleukin 1 (IL-1), more than 90% of both cell types express DR antigens. However, only BM consistently promote antigen-stimulated lymphocyte proliferation. Addition of IL-1 does not restore accessory cell function of human AM for antigen stimulation. It is possible that DR antigen expression and/or function of AM may be more contributory for their accessory cell function. The mixed leucocyte reaction (MLR) and autologous mixed leucocyte reactions (AMLR) in which DR epitopes stimulate proliferation of allogeneic and autologous T cells, respectively, are useful in vitro assays for assessment of DR-restricted macrophage-lymphocyte interactions. In the current studies we demonstrate that AM are usually equivalent to autologous in-vitro-aged BM in their ability to stimulate an MLR, but are consistently deficient relative to such BM in their ability to stimulate an AMLR. Experiments in which the two cells were co-cultured indicate that AM-mediated suppression does not account for the limited ability of AM to stimulate an AMLR. The deficiency of AM to act as accessory cells for antigen-stimulated lymphocyte proliferation may relate to their relative inability to stimulate autoreactive T cells and be attributable to differences in DR antigen expression and/or function.     

T cell adhesion to extracellular matrix molecules secreted by endothelial cells cultured on a substrate of type IV collagen

T cell emigrating from the bloodstream into lymphoid organs or sites of inflammation in the connective tissue must adhere to, and traverse, the subendothelial basement membrane (BM). The goal of the current investigation was to develop a method to study the adhesion of T cells to endothelial cell (EC)-derived extracellular matrix (ECM) as a model for the interaction of T cells with the subendothelial BM in vivo. To be certain that we were truly measuring T cell adhesion to ECM molecules secreted by the EC, it was necessary to culture the EC on a substrate to which T cells could not attach. Non-tissue culture-treated microtiter plate wells which had been coated with type IV collagen (tIVC), a major constituent of BM in vivo, were found to be suitable for this purpose since EC, but very few T cells, adhered to such wells. After incubating the EC on a substrate of tIVC in non-treated wells for a period of 48 h, the EC were gently removed from their underlying ECM and T cell adhesion to that ECM was examined. Using this system, it was observed that approximately 15-40% of human peripheral blood T cells specifically adhered to ECM molecules produced by the EC. This method should be useful as a model for the interactions of T cells and other leukocytes with the vascular BM in vivo.     

Suppression of Cytolytic T-Lymphocyte Responses through Inactivation of Non-T Accessory Cells

The suppressive properties of nonspecific cytotoxic T lymphocyte (CTL) populations, derived from murine fetal calf serum (FCS)-precultured cells expanded in interleukin 2 (operationally defined as FCS-CM-expanded cells), were investigated on CTL responses generated by syngeneic alloreactive lymphoid cells. Our results suggest that the addition of FCS-CM-expanded cell populations can inhibit the CTL response by elimination of the bone marrow-derived macrophage (BM M phi) population used as non-T accessory cells. Indeed, in the culture conditions used, removal of IL-2 by the FCS-CM-expanded cells as well as a direct inactivating effect on the CTL precursors (CTL-P) could be excluded as a reason for inhibition. On the other hand, we were able to show that the BM M phi population was very sensitive to the cytolytic activity exhibited by the inhibiting cells in a 3 h 51Cr-release assay and that the suppressor effect observed could be partially circumvented by a second addition of BM M phi on the second day after the initiation of the culture.     

Transplantation of retrovirally transduced bone marrow prevents autoimmune disease in aged mice by peripheral tolerance mechanisms

Transplantation of bone marrow (BM) engineered to express self-antigen has been shown to protect 100% of young mice from myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), with thymic clonal deletion as a tolerance mechanism. Here, we asked whether aged mice can also be tolerised following transplantation with self-antigen-engineered BM and whether castration-induced thymus regrowth can enhance this outcomes. Then, 50% of aged mice were protected from EAE regardless of castration-induced thymus regrowth. EAE-free and diseased mice demonstrated MOG-specific lymphocyte proliferation and antibody production regardless of castration-induced thymus regrowth, consistent with lack of intrathymic deletion of self-antigen-reactive T cells. Although low chimerism levels ( < 4%) were observed, EAE-free mice showed significantly higher chimerism levels in lymphocytes in peripheral lymphoid organs compared with thymus. CD4⁺CD25⁺ regulatory T cells were elevated in lymph nodes of EAE-free mice. We conclude that transplantation of self-antigen expressing BM protects 50% of aged mice and castration-induced thymic regrowth had no effect on outcomes. Peripheral tolerance mechanisms are implicated since protection is associated with higher chimerism levels in peripheral T and B lymphocytes and with elevated regulatory T cells.     

Transplantation of retrovirally transduced bone marrow prevents autoimmune disease in aged mice by peripheral tolerance mechanisms

Transplantation of bone marrow (BM) engineered to express self-antigen has been shown to protect 100% of young mice from myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), with thymic clonal deletion as a tolerance mechanism. Here, we asked whether aged mice can also be tolerised following transplantation with self-antigen-engineered BM and whether castration-induced thymus regrowth can enhance this outcomes. Then, 50% of aged mice were protected from EAE regardless of castration-induced thymus regrowth. EAE-free and diseased mice demonstrated MOG-specific lymphocyte proliferation and antibody production regardless of castration-induced thymus regrowth, consistent with lack of intrathymic deletion of self-antigen-reactive T cells. Although low chimerism levels (?相似文献   

Flt3L Treatment of Bone Marrow Donors Increases Graft Plasmacytoid Dendritic Cell Content and Improves Allogeneic Transplantation Outcomes

A higher number of donor plasmacytoid dendritic cells (pDCs) is associated with increased survival and reduced graft-versus-host disease (GVHD) in human recipients of unrelated donor bone marrow (BM) grafts, but not granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood grafts. We show that in murine models, donor BM pDCs are associated with increased survival and decreased GVHD compared with G-CSF-mobilized pDCs. To increase the content of pDCs in BM grafts, we studied the effect of FMS-like tyrosine kinase 3 ligand (Flt3L) treatment of murine BM donors on transplantation outcomes. Flt3L treatment (300 μg/kg/day) resulted in a schedule-dependent increase in the content of pDCs in the BM. Mice treated on days -4 and -1 had a >5-fold increase in pDC content without significant changes in numbers of HSCs, T cells, B cells, and natural killer cells in the BM graft. In an MHC-mismatched murine transplant model, recipients of Flt3L-treated T cell-depleted (TCD) BM (TCD F-BM) and cytokine-untreated T cells had increased survival and decreased GVHD scores with fewer Th1 and Th17 polarized T cells post-transplantation compared with recipients of equivalent numbers of untreated donor TCD BM and T cells. Gene array analyses of pDCs from Flt3L-treated human and murine donors showed up-regulation of adaptive immune pathways and immunoregulatory checkpoints compared with pDCs from untreated BM donors. Transplantation of TCD F-BM plus T cells resulted in no loss of the graft-versus-leukemia (GVL) effect compared with grafts from untreated donors in 2 murine GVL models. Thus, Flt3L treatment of BM donors is a novel method for increasing the pDC content in allografts, improving survival, and decreasing GVHD without diminishing the GVL effect.