Immunological reconstitution following bone marrow transplantation

Summary: The recipients of hematopoietic stem cell transplants are characterized by an immunodeficiency of varying severity and duration. Their immunoincompetence is due in part to: 1) a lack of sustained transfer of donor immunity, 2) a recapitulation of lymphoid ontogeny, 3) the effects of graft-versus-host disease and its therapy, and 4) a reduction in thymic function. Recipients can have delays in the production of naive T lymphocytes following transplantation which result in defects in the production of new antigen-specific T lymphocytes and an inability to produce antibodies, especially to carbohydrate antigens.     

T lymphocyte reconstitution following autologous bone marrow transplantation.

Peripheral blood T lymphocyte subpopulations were analysed using OKT3, OKT4 and OKT8 monoclonal antibodies in eleven patients undergoing autologous bone marrow transplantation following high dose chemotherapy +/- total body irradiation for bronchial carcinoma or as intensification therapy for acute myeloblastic leukaemia. Marked inversion of the OKT4:OKT8 ratio was noted in all patients following the procedure. This is due to both a fall in the number of OKT4 positive cells and a rise in the number of OKT8 positive cells in all but one patient. Sequential analysis of six patients shows a return to the normal ratio in two with time and a trend towards normalization in the others. We suggest that the subpopulation inversion noted following bone marrow transplantation is an effect of marrow regeneration and is not causally related to graft versus host disease.     

HLA status following fetal liver transplantation in aplastic anaemia and acute myeloid leukaemia

Fetal liver infusion (FLI) was tried as an alternate mode of therapy in 40 patients with aplastic anaemia and in 16 patients with acute myeloid leukaemia. The fetal HLA typing carried out on spleen and thymus cells revealed that, while it was more difficult to HLA type the thymus than the spleen cells, 'full house' antigens could be determined only in fetuses of 18 weeks or older. No special effort was made to transfuse HLA- matched or partially matched donor cells into the recipient. The recipients were HLA typed at varying time intervals following FLI in an attempt to document a possible chimerism. None of the patients revealed a 'shift' in their HLA antigen profile and there was no evidence of any donor cell engraftment. No relationship between the HLA match of donor and recipient, and the general condition, the prognosis or the total survival of the patient was evidenced. These data indicate that, even though fetal liver cells express HLA antigens, these cells are functionally incompetent to cause an apparent graft-versus-host disease in the host.     

Sustained recovery of hematopoiesis and immunity following transplantation of fetal liver cells in dogs

We studied the ability of fetal liver cells to reconstitute hematopoiesis and immunity in lethally irradiated dogs. Engraftment and sustained lymphoid and hematopoietic recovery was achieved when the recipients received a preparative regime of high-dose total body irradiation (TBI) alone followed by transplantation of DLA-identical fetal liver. The combination of high-dose TBI and cyclosporine allowed engraftment in DLA-mismatched fetal liver transplants. Typical features of graft-versus-host disease (GvHD) did not occur although autoimmune-like syndromes (myasthenia gravis, immune thrombocytopenia) were observed in some recipients. Hematopoietic recovery was rapid and complete. Recovery of T- and B-lymphocyte function was comparatively delayed, but sufficient to prevent opportunistic infections after the initial 3 months post transplant. These data indicate that cells from a single fetal liver can reconstitute hematopoiesis and immunity in DLA-mismatched recipients and suggest that human fetal liver cell transplantation may be an effective source of stem cells for patients who lack an HLA-identical donor for bone marrow transplantation.     

Effects of alveolar macrophage depletion on liposomal vaccine protection against respiratory syncytial virus (RSV)

Little is known about the identities and roles of antigen-presenting cells upon exposure to antigens of respiratory syncytial virus (RSV). Here, we focused on elucidating the importance of alveolar macrophages in conferring protective immunity in mice administered a liposome-encapsulated recombinant fragment of the RSV G protein. Mice were depleted of alveolar macrophages by intranasal inoculation of liposome-encapsulated dichloromethylenediphosphonic acid (DMDP). Mice depleted of alveolar macrophages prior to immunization developed reduced levels of serum RSV-neutralizing antibody and showed dramatically impaired protection against RSV challenge. The severity of interstitial inflammation was also markedly reduced in macrophage-depleted mice. In conclusion, this study demonstrates a pivotal role for alveolar macrophages during exposure to liposome-encapsulated RSV antigen in initiating both protective and histopathological responses against RSV.     

PTEN limits alveolar macrophage function against Pseudomonas aeruginosa after bone marrow transplantation

Hematopoietic stem cell transplant patients are susceptible to infection despite cellular reconstitution. In a murine model of syngeneic bone marrow transplantation (BMT), we previously reported that BMT mice have impaired host defense against Pseudomonas aeruginosa pneumonia due to overproduction of (PG)E(2) in lung. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is an effector in the PGE(2) signaling pathway that negatively regulates alveolar macrophage (AM) phagocytosis and bacterial killing. Therefore, examined whether overproduction of PGE(2) after BMT inhibits AM host defense by up-regulating PTEN phosphatase activity. We found that PTEN activity is elevated in BMT AMs in response to increased PGE(2) signaling and that pharmacological inhibition of PTEN activity in BMT AMs fully restores phagocytosis of serum-opsonized P. aeruginosa but only partially restores phagocytosis of nonopsonized P. aeruginosa. In wild-type mice transplanted with myeloid-specific conditional PTEN knockout (PTEN CKO) bone marrow, bacterial clearance is improved after challenge with P. aeruginosa pneumonia. Furthermore, PTEN CKO BMT AMs display improved TNF-α production and enhanced phagocytosis and killing of serum-opsonized P. aeruginosa despite overproduction of PGE(2). However, AM phagocytosis of nonopsonized P. aeruginosa is only partially restored in the absence of PTEN after BMT. This may be related to elevated AM expression of IL-1 receptor-associated kinase (IRAK)-M, a molecule previously identified in the PGE(2) signaling pathway to inhibit AM phagocytosis of nonopsonized bacteria. These data suggest that PGE(2) signaling up-regulates IRAK-M independently of PTEN and that these molecules differentially inhibit opsonized and nonopsonized phagocytosis of P. aeruginosa.     

Immunologic reconstitution following bone marrow transplantation for X-linked hyper IgM syndrome

X-linked hyper IgM syndrome (XHIM), caused by mutations of the CD40 ligand (CD40L) gene, is characterized by recurrent bacterial and opportunistic infections, an increased incidence of autoimmunity and malignancies, and immunodeficiency due to abnormal T/B cell interaction. Because of poor long-term prognosis, bone marrow transplantation (BMT) has been proposed as an alternative treatment. An 8-month-old boy with XHIM and a splice site mutation of CD40L underwent BMT using a fully matched sibling donor. Markers of engraftment and immunologic reconstitution were measured serially. After BMT, activated T cells expressed functional CD40L, and genomic DNA obtained from circulating white cells contained predominantly wild-type CD40L sequences. Serum immunoglobulin levels including IgE and antibody responses to recall antigens normalized, and immunization with the T-cell-dependent neoantigen, bacteriophage φX174, demonstrated amplification of the response and isotope switching. BMT provides a permanent cure for XHIM if a fully matched sibling donor is available and the procedure is performed before complications have occurred.     

Synopsis and prospectives on fetal liver transplantation

Over 300 individuals have received fetal liver transplants for a spectrum of disorders including immunodeficiencies, aplastic anemia, leukemia and genetic disorders. In some instances, the objective has been to reconstitute the immune system from fetal liver-derived lymphoid stem cells. In aplastic anemia and leukemia two distinct approaches have been used: engraftment of fetal liver-derived hematopoietic stem cells or attempts to stimulate recovery of autologous hematopoiesis via factors produced by fetal liver. In genetic disorders, partial engraftment of fetal liver-derived hematopoietic and hepatic cells has been investigated. This report critically reviews data presented at a symposium on fetal liver transplantation in New-Delhi, 1-5 February 1986.     

Survey of experimental data on fetal liver transplantation

Fetal liver transplantation has been shown to induce hematological and immunological reconstitution in irradiated rodents, dogs, horses, and sheep. Engraftment and reconstitution without GvHD has been readily obtained using histocompatible donors. When mismatched fetal donors were used, a comparatively larger number of donor cells was required, in addition to pre-treatment of host with higher doses of irradiation or irradiation plus chemotherapy. Stem cell suspensions devoid of any T lymphocyte can be transplanted across major histocompatibility barrier without inducing overt GvHD. The transplanted animals become tolerant to both donor and host grafts.     

Studies on engraftment following fetal liver infusion

Studies to find engraftment following fetal liver infusion (FLI) in aplastic anaemia (AA) and acute myeloid leukaemia (AML) were carried out in 24 patients (17 AA and 7 AML patients) out of the 56 who received FLI. HLA studies done in 13 patients (3 AA and 5 AML), repeatedly after FLI, showed no significant change in HLA antigen pattern before and after FLI. Red cell antigen studies were done in five (1 AA and 4 AML) patients, 3 weeks to 7 months after FLI. One patient with AML who was Rh negative prior to reinduction chemotherapy became Rh positive two months after FLI; six months later he was Rh negative again. In the remaining patients there was no change in red cell antigen pattern after FLI. Radio-immuno-assay to detect alpha-fetoprotein levels, carried out in 10 (8 AA and 2 AML) patients repeatedly after FLI, demonstrated no increase. In 13 patients (8 AA and 5 AML) in whom there was a sex difference between donor and recipient, bone marrow cultures for sex chromosomes revealed mixture of XX and XY cells in 3 male patients with aplastic anaemia. One male patient with AML demonstrated complete engraftment after induction chemotherapy and FLI: all the mitoses studied were of XX pattern. Engraftment was however temporary as repeated studies revealed reversion to XY pattern. The present work suggests that infusion of fetal liver cells may sometimes induce temporary chimerism or engraftment in an adult host; in the majority of cases, however, engraftment could not be established.     

Immune reconstitution following hematopoietic stem cell transplantation using different stem cell sources

ABSTRACT

Introduction: Adequate immune reconstitution post-HSCT is crucial for the success of transplantation, and can be affected by both patient- and transplant-related factors.

Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses is performed to investigate immune recovery posttransplant. In this review, we discuss the pattern of immune recovery in the post-transplant period focusing on the impact of stem cell source (bone marrow, peripheral blood stem cells, and cord blood) on immune recovery and HSCT outcome. We examine the impact of serotherapy on immune reconstitution and the need to tailor dosing of serotherapy agents when using different stem cell sources. We discuss new techniques being used particularly with cord blood and haploidentical grafts to improve immune recovery in each scenario.

Expert opinion: Cord blood T cells provide a unique CD4+ biased immune reconstitution. Initial studies using targeted serotherapy with cord grafts showed improved immune recovery with limited alloreactivity. Two competing haploidentical approaches have developed in recent years including TCRαβ/CD19 depleted grafts and post-cyclophosphamide haplo-HSCT. Both approaches have comparable survival rates with limited alloreactivity. However, delayed immune reconstitution is still an ongoing problem and could be improved by modified donor lymphocyte infusions from the same haploidentical donor.     

Rapid thymic reconstitution following bone marrow transplantation in neonatal mice is VEGF-dependent

Age-related differences in thymic function influence the rapidity of T cell reconstitution following hematopoietic stem cell transplantation (HSCT). In adults, thymic reconstitution is delayed until after marrow engraftment is established, and is significantly improved by approaches that increase marrow chimerism, such as pretransplantation irradiation. In contrast, we show that neonatal mice undergo more rapid and efficient thymic reconstitution than adults, even when bone marrow (BM) engraftment is minimal and in the absence of pretransplantation radiation. We have previously shown that the neonatal thymus produces high levels of vascular endothelial growth factor (VEGF) that drives angiogenesis locally. In this report, we show that inhibition of VEGF prior to HSCT prevents rapid thymic reconstitution in neonates, but has no effect on thymic reconstitution in adults. These data suggest that the early radiation-independent thymic reconstitution unique to the neonatal host is mediated through VEGF, and reveals a novel pathway that might be targeted to improve immune reconstitution post-HSCT.     

Timely reconstitution of immune competence affects clinical outcome following autologous stem cell transplantation

Abstract. The anti-tumor activity of the immune system in the setting of hematopoietic stem cell transplantation has largely been described in the context of the graft-versus-tumor effect of allogeneic stem cell transplantation. This article reviews clinical evidence suggesting the existence of an autologous graft-versus-tumor effect in the setting of host immune system recovery following autologous stem cell transplantation resulting in prolongation of survival of cancer patients.     

Oral administration of nimodipine accelerates functional recovery following peripheral nerve damage in the rat

Oral administration of the Ca2+-entry blocker nimodipine accelerates in a dose-dependent manner the recovery of sensorimotor function following a crush lesion of the rat sciatic nerve. The beneficial effect of nimodipine was apparent in both a foot shock withdrawal test and in a test analyzing the walking pattern of the rat. These data are the first demonstration of nimodipine-induced enhanced recovery following peripheral nerve damage.     

Pleural posttransplantation lymphoproliferative disorder following liver transplantation

A case of posttransplantation lymphoproliferative disorder (PTLD) involving the pleura is reported. The patient was a 57-year-old man who underwent liver transplantation 2 years prior to the development of PTLD. The PTLD was pleural-based and was first detected by radiologic studies as a pleural effusion. Transbronchial biopsy and cytologic examination of 2 pleural fluid specimens were nondiagnostic. Subsequent open-wedge biopsy revealed a monomorphic PTLD, composed of large immunoblasts with plasmacytoid differentiation. Immunohistochemical studies demonstrated B-cell lineage with expression of monotypic cytoplasmic immunoglobulin kappa light chain and CD79a, and absence of T-cell antigens. Immunohistochemical and in situ hybridization studies demonstrated Epstein-Barr virus protein and RNA, respectively. No evidence of human herpesvirus 8 DNA was detected by polymerase chain reaction. We report this case because pleural-based PTLD is rare. The diagnosis of this entity is made more difficult by the fact that PTLD is often underrepresented in pleural fluid cytology samples.     

Characteristics of bovine alveolar macrophage elastase

Lavage of isolated bovine lung lobes was used to retrieve pulmonary alveolar macrophages (PAM). Nominal yields of 72 million viable PAM were routinely obtained using 500 ml of calcium- and magnesium-free phosphate-buffered saline. Bovine PAM readily attached to glass coverslips and within 24 hours, provided cell monolayers consisting exclusively of macrophages. Bovine PAM synthesized and secreted a calcium-dependent elastase in serum-free media. Optimal proteolytic activity using a radiolabeled elastin substrate was observed at pH 7.6. The elastase was insensitive to synthetic peptide chloromethyl ketone elastase inhibitors and to the serine protease inhibitor, phenylmethylsulfonyl fluoride. Enzyme activity, however, was effectively inhibited by the metal chelator, ethylenediaminetetraacetic acid, or suppressed by inhibition of protein synthesis with cycloheximide.     

细胞凋亡与肝移植缺血再灌注损伤

背景：肝脏缺血再灌注损伤是影响肝脏移植效果的重要因素,细胞凋亡是移植肝缺血再灌注损伤的重要机制之一。 目的：就近年来细胞凋亡与移植肝缺血再灌注损伤的研究做一综述,为抗细胞凋亡在减轻器官缺血再灌注损伤的临床应用提供参考依据。 方法：由第一作者检索1990/2010 PubMed数据库及中国期刊全文数据库有关细胞凋亡及器官移植缺血再灌注损伤的关系的文献,检索词为“apoptosis,organ transplantation,ischemia-reperfusion injury”。排除重复性研究。计算机初检得到339篇文献,最终纳入39篇文献进行下一步分析。 结果与结论：文章从肝脏移植缺血再灌注损伤中的细胞凋亡,移植肝缺血再灌注损伤中细胞凋亡发生的机制,移植肝缺血再灌注损伤中细胞凋亡的基因表达变化,抗凋亡治疗与防治肝移植缺血再灌注损伤几方面进行了叙述。细胞凋亡与移植肝缺血再灌注损伤有着密切的关系。而抑制细胞凋亡可以有效的减轻移植肝的缺血再灌注损伤,对提高移植物的存活率有着重要的意义。     

当归补血汤对骨髓移植小鼠免疫功能重建的影响

目的 研究当归补血汤(DBT)对骨髓移植小鼠免疫功能重建作用的影响.方法 BALB/c小鼠一次性接受全身137Csγ线致死量照射8.5Gy,照射后0-4h内经尾静脉输注同基因骨髓细胞107/只,同时给于不同剂量DBT,每日灌胃1次,连续15d.于骨髓移植后30、60d,检测以下指标:外周血红细胞(RBC)、白细胞(WBC)计数,骨髓有核细胞计数,胸腺、脾细胞总数和相应淋巴细胞亚类,以及反映免疫细胞功能的迟发型超敏反应(DTH)、空斑形成细胞数(PFC)等.结果 经一定剂量DBT治疗的骨髓移植小鼠,其外周血中RBC、WBC计数,骨髓有核细胞计数,脾细胞和胸腺细胞总数,胸腺内各类细胞[双阴性细胞(DN)、双阳性细胞(DP)、单阳性细胞(SP)]的百分比值,与单纯骨髓移植小鼠比较差异有统计学意义(P<0.05),并且淋巴细胞的功能也得到进一步增强.到移植后60d,其各项指标进一步恢复.结论 当归补血汤可以促进骨髓移植小鼠免疫功能的恢复.