In vitro infection of megakaryocytes and their precursors by human cytomegalovirus.

Apart from congenital human cytomegalovirus (HCMV) infection, manifest HCMV disease occurs primarily in immunocompromised patients. In allogeneic bone marrow transplantation, HCMV is frequently associated with graft failure and cytopenias involving all hematopoietic lineages, but thrombocytopenia is the most commonly reported hematologic complication. The authors hypothesized that megakaryocytes (MK) may be a specific target for HCMV. Although the susceptibility of immature hematopoietic progenitors cells to HCMV has been established, a productive viral life cycle has only been linked to myelomonocytic maturation. The authors investigated whether HCMV can also infect MK and impair their function. They demonstrated that HCMV did not affect the thrombopoietin (TPO)-driven proliferation of CD34(+) cells until MK maturation occurred. MK challenged with HCMV showed a 50% more rapid loss of viability than mock-infected cells. MK and their early precursors were clearly shown to be susceptible to HCMV in vitro, as evidenced by the presence of HCMV in magnetic column-purified CD42(+) MK and 2-color fluorescent staining with antibodies directed against CD42a and HCMV pp65 antigen. These findings were confirmed by the infection of MK with a laboratory strain of HCMV containing the beta-galactosidase (beta-gal) gene. Using chromogenic beta-gal substrates, HCMV was detected during MK differentiation of infected CD34(+) cells and after infection of fully differentiated MK. Production of infectious virus was observed in cultures infected MK, suggesting that HCMV can complete its life cycle. These results demonstrate that MK are susceptible to HCMV infection and that direct infection of these cells in vivo may contribute to the thrombocytopenia observed in patients infected with HCMV. (Blood. 2000;95:487-493)

Pre-treatment of transplant bone marrow cells with hydrocortisone and cyclosporin A alleviates graft-versus-host reaction in a murine allogeneic host-donor combination.

The aim of the study was to alleviate graft-versus-host reaction (GVHR) by pre-treatment of the bone marrow (BM) transplant with hydrocortisone (HC) and cyclosporin A (CsA) in C57BL/6J (donor) --> CBA/J (recipient) mouse combination. BM cells were exposed to HC and CsA for 1 h at 37 degrees C and then injected into lethally irradiated (9.5 Gy) mice at a dose of 2 x 10(6) BM cells/mouse. Haematopoietic recovery was assessed on day 12, and survival was followed for 100 days. Combinations of 1000 microg/ml HC and 100 microg/ml CsA, and 100 microg/ml HC and 10 microg/ml CsA significantly reduced MLR and additively mitigated GVHR in vivo, achieving 40% and 26% survival rates, respectively. However, HC and CsA altered neither the peripheral blood cell counts nor in vitro and in vivo BM cell clonogenic potential. Additional studies have shown that HC and CsA blocked con A-driven differentiation of CD8+ and CD4+ CD8+ lymph node cells (LNC) and progression of LNC to S + G2/M cell cycle phases, and inhibited IL-1, IL-2 and TGF-beta while enhancing GM-CSF gene expression in BM cells. Taken together, these data indicate that the pre-treatment of the BM transplant with HC and CsA results in inactivation of GVHR effector cells and mitigation of GVHR while sparing BM repopulating capacity.

Human natural killer cells.

Human natural killer (NK) cells comprise 10 to 15% of peripheral blood lymphocytes, characterized by their morphologic appearance of large granular lymphocytes (LGLs) and phenotype CD3- CD56+ CD16+ or CD16-. Functionally, these cells are defined by their ability to lyse target cells without prior sensitization and without restriction by major histocompatibility (MHC) antigens. These cells play an important role in immune defenses, especially after hematopoietic transplantation. They contribute to the defenses against virus-infected cells, graft rejection, and neoplasias; they also participate in the regulation of hematopoiesis through cytokine production and cell to cell interaction. In this mini-review we attempt to summarize the most relevant findings about these cells in terms of their origin and differentiation, their cell surface characteristics including activation and their cytolytic pathways. We have also provided a brief approach of their potential clinical use. Increased knowledge of NK cell differentiation, ontogeny and regulatory mechanisms may be of use for the planning of immunotherapeutic strategies.

Human thymic stroma supports human natural killer (NK) cell development from immature progenitors.

NK cells are lymphocytes which exhibit spontaneous cytotoxicity against a variety of target cells, including cancer cells. Mature NK and T cells may derive from a common precursor which differentiates into T or NK cells depending on the microenvironment. We evaluated the effect of human fetal thymic stroma on human CD34+Lin- progenitors. The culture medium was supplemented with human AB serum with or without interleukin-2 (IL2; 1000 U/ml) and interleukin-7 (IL7; 1000 U/ml). After 3 weeks of culture, CD45/56 cells were detected by flow cytometry and their activity was tested against K562 targets. In cultures with IL2 the percentage of CD56-positive cells was much higher in the Transwell cultures (60.8 +/- 12.5% from CD34+Lin-DR+ and 51% from CD34+Lin-progenitors) than in adherent cultures (25 +/- 21.9% from CD34+Lin-DR+ and 25.3 +/- 9.5% from CD34+Lin-progenitors) or suspension cultures (23 +/- 21.4% from CD34+Lin-DR+ progenitors and 43.1 +/- 14.2% from CD34+Lin-progenitors). Cytolytic activity as measured by K562 lysis was also higher in Transwell cultures with IL2. NK cells were also obtained in cultures without factors or supplemented with IL7, but in smaller numbers. These data indicate that NK cells can be obtained in vitro by coculture of immature hematopoietic progenitors with thymic stromal cells and that IL2 appears to strongly favor their development in the absence of stromal contact. This would indicate a direct inhibitory effect of the thymic stroma on NK progenitors.

Definition of early progenitors and functional maturation of human natural killer cells: requirements for cytocidal activity.

We examined the in vitro development of human natural killer (NK) cells to define the earliest hematopoietic progenitors which could give rise to NK cells. Our data indicates that NK cells arise from the Thy 1+ subpopulations of CD34+ marrow cells. In cultures with IL2 we generated up to 96.5% NK cells from CD34+ Thy 1+ and in cultures with IL7, cells bearing NK cell surface markers were also observed but were devoid of functional activity. We also addressed the functional integrity of these cultured cells by examining the appearance of granzyme A, serine esterase, Met-ase and perforin and correlating these with lytic activity. Granzyme A mRNA could be detected in IL2-cultured cells and serine esterase activity as well as perforin were also found at the single cell level. Human Met-ase (Hu-Met-1) was not detected at any time of analysis. Granzyme expression occurs early in cells cultured with IL2 but its presence did not correlate with lytic function; CD56+ cells grown in the presence of IL7 express these enzymes and perforin after longer periods of culture, but lack the ability to lyse NK targets.

Altered production of GM-CSF and IL-8 in cytomegalovirus-infected, IL-1-primed umbilical cord endothelial cells.

The human cytomegaloviruses (HCMVs) appear to have the potential to disrupt production of hematopoietic cytokines. We examined the production of granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-8 by cultured and CMV-infected human umbilical vein endothelial cells (HUVECs) and compared this production with that of uninfected cells. Endothelial cells are, among other things, an integral component of human bone marrow stroma, and are responsible for production of factors that modulate the proliferation and differentiation of human hematopoietic progenitors. HCMV infection increased the production of GM-CSF in IL-1-primed HUVECs without altering GM-CSF levels in infected but unprimed HUVECs. However, this same virus was capable of causing increased production of the inhibitory cytokine IL-8. Both the viral pellet and the cleared viral supernatant appeared to contribute equally to the increased IL-8 and GM-CSF production, because each of these preparations alone was capable of exerting only half the effect seen with whole virus preparations. That both live virus and soluble protein factors within the viral stock contributed to the enhancement in GM-CSF and IL-8 production was further confirmed by inactivation with either ultraviolet or heat treatment of the viral stocks. Although the identity of the factor within the HCMV stock that contributes to this effect remains unknown, studies conducted in the presence of neutralizing antibodies or polymyxin B ruled out a role for tumor necrosis factor-alpha, IL-6, or endotoxin, all known inducers of GM-CSF. These studies indicate that HCMVs can exert both direct and indirect effects on the production of the hematopoietic factor GM-CSF and the inflammatory/inhibitory cytokine IL-8.

A novel high-dose chemotherapy protocol with autologous hematopoietic rescue in patients with metastatic breast cancer or recurrent non-Hodgkin's lymphoma.

In this phase II trial, we used a double dose-intensive chemotherapy and stem cell rescue protocol to treat breast cancer (BCA) patients or non-Hodgkin's lymphoma patients (NHL). The first cycle consisted of high-dose melphalan followed by ABMT. The second cycle used a novel chemotherapy combination; thiotepa, etoposide, carboplatin and cyclophosphamide (TECC) followed by ABMT. We treated 12 patients in total, nine with BCA, three with NHL. All nine BCA patients were treated with the two cycle protocol. The three NHL patients were treated with the second cycle only. Bone marrow (BM, 1 patient), peripheral blood stem cells (PBSC, 10 patients) or both (1 patient) were reinfused 60-72 h after completion of each cycle of chemotherapy. Recovery was rapid; the ANC rose to greater than 500/microl on day +11 (+8 to + 20) and the platelet count to greater than 20000/microl on day +12 (+6 to +20). The toxicities included the expected neutropenic fevers, severe mucositis, diarrhea, and a low incidence of mild renal insufficiency. No patients developed veno-occlusive disease, hemorrhagic cystitis or overt bleeding. With a mean follow-up of 37 months, 83.3% of the patients are alive. Six patients are in complete remission; one patient with BCA relapsed and expired; one patient with NHL is in CR now over 18 months after relapse and subsequent treatment with interferon; one patient is too early to evaluate. Progression-free survival overall is 75%, which is at least equivalent to many other recent studies using similar regimens. In addition, we have also found that delayed addition of G-CSF during the mobilization of PBSC was feasible and resulted in excellent CD34+ cell counts and engraftments, and reduced treatment costs. These results indicate that this chemotherapy is effective with good remission rates and high progression-free survival rates. It is also well tolerated with acceptable toxicities that are manageable. Long-term follow-up of a larger cohort of patients will be needed to ascertain the overall efficacy of this type of therapy.

Transplantation of hematopoietic stem cells in utero.

Hematopoietic stem cell (HSC) transplantation in children and adults with congenital lymphohematopoietic disorders is limited by donor availability, graft failure, graft-versus-host disease (GVHD) and delayed immunological reconstitution. These problems may be circumvented by transplanting the patient before birth. Prenatal cellular therapy for the treatment of congenital diseases has tremendous theoretical appeal. Potential advantages of prenatal transplantation include: A) fetal immunologic immaturity and the potential for induction of donor-specific tolerance; B) available space in the developing bone marrow for engraftment of donor cells; C) the sterile, protective, fetal environment which provides isolation from environmental pathogens, and D) prevention of clinical manifestations of the disease. Normal hematopoietic and immunologic development during ontogeny creates a "window of opportunity" during which events favor the engraftment of transplanted allogeneic (and xenogeneic) HSC and their proliferation. This is a period in which the fetus is immunologically naive and thus incapable of rejecting the foreign HSC, and the expanding bone marrow spaces allow homing and engraftment of HSC without the need for myeloablation. Experiments in sheep have established the optimal age of the recipient, route of donor cell administration, sources of HSC, and other parameters necessary for the successful engraftment and long-term expression of donor HSC. In preclinical studies, transplantation of CD34-enriched or highly purified populations of human adult bone marrow cells in utero resulted in the long-term engraftment and expression of donor HSC without graft failure and GVHD. The strategies developed in allogeneic and xenogeneic fetal sheep models were used to successfully treat human fetuses with X-linked recessive severe combined immunodeficiency.

Isolation, characterization, and biologic features of bone marrow endothelial cells.

Bone marrow endothelial cells (BMECs) are an integral part of the bone marrow microenvironment and are likely to play an important role in the regulation of hematopoiesis, either by producing growth factors or inhibitory cytokines or by displaying adhesion molecules that can interact with hematopoietic progenitors. In the present study we demonstrate the isolation, propagation, and characterization of BMECs with regard to morphology, growth characteristics, phenotype, and production of cytokines. Furthermore, we report the creation of a cell line with "BMEC-like" characteristics and compare the characteristics of primary BMEC cultures to those of the immortalized cell line. In addition, we demonstrate that BMECs are susceptible to infection by a laboratory strain of human cytomegalovirus (CMV), suggesting that CMV infection of endothelial cells in vivo could potentially play a role in the hematologic abnormalities observed during CMV infection.

The role of sheep stroma in human haemopoiesis in the human/sheep chimaeras.

We have previously reported on the successful engraftment and long-term expression of human HSC (haemopoietic stem cells) in sheep following transplantation into pre-immune fetuses. The mechanism(s) underlying the support/maintenance of human haemopoiesis in sheep is not understood. In these studies we examined the ability of sheep stroma to support human haemopoiesis in vitro and compared this with support provided by human stroma. We found that, overall, human stroma was significantly more effective than sheep stroma in supporting human haemopoiesis in vitro. Nevertheless, stroma established from bone marrow of normal sheep was capable of lower-level support of the proliferation and multilineage differentiation of highly purified (CD34+, CD38-) preparations of human HSC in vitro. At lower concentrations, sheep stroma conditioned media (CM) induced human bone marrow mononuclear cells enriched for the CD34-positive fraction to enter the cell cycle at levels comparable to that of human stroma CM. However, unlike human CM, at higher concentrations, sheep CM inhibited human cells from initiating the cell cycle. These results provide a possible explanation for the long-term maintenance of low levels of human haemopoietic cell activity in human/sheep chimaeras.

Cytomegalovirus as a cause of pancytopenia.

Human cytomegalovirus, HCMV, infects most of the population by adulthood; The primary infection is often accompanied by transient neutropenia and thrombocytopenia, and is followed by a period asymtomatic viral latency. In the setting of bone marrow transplantation, however, the immunosuppressed state of the recipient enables HCMV to re-activate or to infect the individual and cause serious sequelae. These range from hepatitis and gastrointestinal disease to interstitial pneumonia and hematologic abnormalities, which are more common in the allograft. Little is currently known about the mechanisms by which HCMV causes these hematologic abnormalities. In this review, we discuss experimental models which are helping investigators understand the immunology and pathology of CMV infection. We also summarize the vivo studies of the effects of HCMV on human hematopoiesis. Several possible mechanisms that could explain the deleterious effect of HCMV on human hematopoietic function include: 1) alteration of accessory cell function by inducing the production of inhibitory cytokines; 2) perturbation of stromal cell function resulting in a decreased production of hematopoietic factors or by altering cell surface adhesion molecule expression; 3) by direct infection of the hematopoietic stem or progenitor cells. It is likely that the pathogenesis of this syndrome is multifactorial therefore requiring a broad therapeutic approach. This would include the use of the antiviral agents, hematopoietic growth factors and donor derived HCMV specific cytolytic cells.

Natural killer cell numbers and activity in mobilized peripheral blood stem cell grafts: conditions for in vitro expansion.

Peripheral blood stem cells (PBSC) are increasingly being used as an alternative to autologous bone marrow (BM) for hematologic rescue after high-dose chemoradiotherapy in the treatment of hematologic and nonhematologic malignancies. Mobilization procedures such as chemotherapy and/or hematopoietic growth factor administration are employed to allow for the graft enrichment in hematopoietic stem cells and progenitors and to accelerate trilineage recovery after transplant. The influence of these mobilization procedures on the lymphoid populations in the graft and on immunologic recovery after transplant remains to be determined. We studied six consecutive patients undergoing PBSC high-volume collections after cyclophosphamide (Cyc) and granulocyte colony-stimulating factor (G-CSF) administration and observed that NK cell numbers (phenotypically defined as CD3-CD56+ by flow cytometry) and activity (evaluated by a 51Cr release assay) fully recovered after 4-5 weeks; high numbers of functionally active NK cells (42.1-212.1 x 10(6)/kg b.w.) were present in the grafts, and their percentage and cytotoxic activity rose from the beginning to the end of the harvesting procedure in most cases. CD3-CD56+ and CD34+ cell numbers peaked at the same time point during harvesting, which differed from one patient to another. T (CD3+) cells were always present during harvest, and CD4 and CD8 numbers showed interdonor variability. When we cultured leukapheresed PBSC in the presence of interleukin-2 (IL-2) (10-1000 U/mL) for 6-8 days, we were able to expand the NK population three- to 5.4-fold; 100 U/mL appears to be the best concentration to generate high numbers of cytotoxic NK cells. Pilot studies also suggest that this short exposure to IL-2 does not affect the CD34+ cells. We conclude that PBSC grafts mobilized by combined Cyc and G-CSF and harvested through high-volume leukapheresis contain high numbers of cytotoxic NK cells that can be expanded in vitro by exposure to IL-2. In the setting of PBSC transplant, ex vivo immunomodulation aimed at increasing the NK cell numbers and activity is feasible and may prove to be useful in inducing a graft-vs.-tumor effect, thereby decreasing the relapse rate after transplant.

Enhanced lymphokine-activated killer cell activity by an immunomodulator, Roquinimex.

Roquinimex (Roq) is an immunomodulator known to stimulate cellular immune responses. It is currently used for immunotherapy after bone marrow transplantation (BMT). One of the major features of this compound is an enhancement of natural killer (NK) cell activity and numbers. We studied the in vitro effect of Roq on human peripheral blood NK and adherent lymphokine-activated killer cell (ALAK) activities. In cultures supplemented with recombinant interleukin 2 (rIL-2) (1000 U ml-1) and Roq a significant increase in NK and LAK function was observed without a parallel increase in cell numbers. We also examined the generation of NK cells from human bone marrow (BM) immature progenitors, obtained by purging with 4-hydroperoxycyclophosphamide (4HC). NK cell numbers and activity were both increased when cultures with rIL-2 (10 U ml-1) were supplemented with Roq. These results confirm findings obtained in vivo and in vitro in the murine system and suggest that Roq is an active agent on these lymphoid populations. These properties and good tolerability make Roq an attractive tool for immunotherapy.

In vitro effects of etoposide purging on natural killer cells.

Autologous bone marrow transplantation (ABMT) is widely used to treat hematologic and non-hematologic malignancies. In an attempt to reduce potential neoplastic contamination of the graft, pharmacologic purging with cyclophosphamide derivatives and etoposide (VP16) is often used. Trilineage hemopoietic engraftment is seen following ABMT with VP16-purged bone marrow (BM), but little is known about immune reconstitution in this setting. We studied the in vitro development of natural killer (NK) cells from VP16-purged BM. These cells, defined by phenotypic and functional criteria, undergo rapid regeneration, expansion, and maturation in the presence of interleukin 2 (IL-2). VP16 seems to spare subsets of NK cells, and this cell lineage develops rapidly in VP16-treated BM cultures from patients with acute myelogenous leukemia (AML) and healthy donors. Since relapse rates remain high, immunotherapy following ABMT with purged BM may be useful and should be considered in these patients.

Generation of human natural killer cells from pharmacologically purged bone marrow.

Human natural killer (NK) cells play an important role in first-line defence against primary and metastatic tumours. Their stimulation after autologous bone marrow transplantation (ABMT) may be useful to eradicate residual tumour cells. Human NK cells originate in bone marrow (BM) but little is known about their progenitors and lineage development. We studied NK cell ontogeny from BM progenitors obtained by 'purging' normal BM with 4-hydroperoxycyclophosphamide (4HC); this agent is known to destroy all but the most primitive BM progenitors. NK cells, defined by their phenotypic markers and cytolytic activity, could be generated from 4HC-treated BM cells during in vitro cultures over stromal BM feeder layers and in suspension cultures containing a mixture of soluble cytokines; Interleukine 2 appears to be essential for the full development of this population. A lag period exists before NK cells can be found in significant numbers in culture; this suggests that a delay in initiation of immunotherapy after ABMT ought to be considered, particularly when using purged marrow.

Phase I/II study of cyclophosphamide, carboplatin, and etoposide and autologous hematopoietic stem-cell transplantation with posttransplant interferon alfa-2b for patients with lymphoma and Hodgkin's disease.

PURPOSE: To evaluate the safety and toxicity of interferon alfa-2b (IFN) following an intensive preparative transplantation regimen in patients with relapsed Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL). PATIENTS AND METHODS: Thirty-two patients with NHL or HD underwent autologous transplantation following cyclophosphamide 7,200 mg/m2, carboplatin 1,600 mg/m2, and etoposide 1,600 mg/m2 (CCV). Fourteen patients received an escalating dose of IFN. IFN was started at 1 x 10(6) U/m2 subcutaneously (SC) three times per week with a monthly dose escalation to a maximum of 3 x 10(6) U/m2 SC three times per week. IFN was continued for a total of 6 months. RESULTS: The preparative regiment was well tolerated. Renal dysfunction was noted more frequently in patients with a history of pretransplant cisplatin treatment, and cardiac dysfunction was responsible for the single transplant-related death (3%). IFN was well tolerated with no serious complications. Transient neutropenia and thrombocytopenia were noted in several patients. The mean maximal-dose IFN achieved was 2 x 10(6) IU/m2. The median duration of treatment with IFN was 5.2 months. The overall probability of survival (OS) and event-free survival (EFS) at 36 months, with a median follow-up duration of 18 months, was 42% OS and 14% EFS in HD and 70% OS and 56% EFS in NHL. The EFS at 36 months was 73% for all NHL patients who received IFN and 50% for patients who refused IFN treatment (P = .12), with OS estimates of 100% in the IFN group and 35% in the untreated group (P = .0002). CONCLUSION: CCV is a safe, effective conditioning regimen in patients with NHL or HD. Posttransplant IFN can be safely administered at 2.0 x 10(6) U/m2 three times per week for 6 months and may have a meaningful antitumor effect.

[Bases for the teaching of oncology]. / Bases do ensino de oncologia.

We define the parameters for preclinical and postgraduate teaching in oncology coupled with hematology with a view to train competent physicians in these areas as well as to encourage a restructuring of the health system to permit optimal delivery of care to all people. We analyze and define curricular changes in the medical schools to be implemented at a national level with the introduction of an intensive course in hematology-oncology during the clinical clerkships. This course would require a host of appropriate teachers, continued monitoring and a final appropriate written exam. The Oncologic training of the medical student requires an interdisciplinary approach with an emphasis on the personalized approach to the patient with cancer. The postgraduate training should follow minimal guidelines established by the ESMO, EORTC and ABIM with an emphasis on combined training in oncology/hematology, following appropriate training in internal medicine. A need for continued "recycling" of generalists in oncology is felt to be important. Other issues discussed include: methods of teaching and their evaluation; the career pathway for the scientist (docent) in oncology; preventive medicine and finally the need for continuing medical education. An evaluation of the quality of medicine and of ethical and professional conduct while not specifically linked to oncology is considered a vital part of medical care and needs to be placed in perspective.

Generation of human natural killer cells from immature progenitors does not require marrow stromal cells.

Human natural killer (NK) cells comprise 10% to 15% of peripheral blood mononuclear cells and have an important role in immune responses against tumors, viral infections, and graft rejection. NK cells originate in bone marrow (BM), but their progenitors and lineage development have not been completely characterized. We studied the generation of NK cells from purified CD34+HLADR- and CD34+HLADR+ BM progenitors and the influence of various cytokines on their production. We show that CD3-CD56+ cytotoxic NK cells can develop from both progenitors populations when interleukin-2 (IL-2) is present in an in vitro suspension culture system containing IL-1 alpha and stem cell factor. Up to 83.8% and 98.6% CD3-CD56+ cells were detected in CD34+HLADR- and CD34+DR+ cultures, respectively, after 5 weeks of culture; significant numbers of NK cells were first detected after 2 weeks. Cytotoxic activity paralleled NK cell numbers; up to 70% specific lysis at an effector:target ratio of 10:1 was observed at 5 weeks. IL-7 also triggered development of CD3-CD56+ cells from these immature progenitors (up to 24% and 55% appeared in CD34+HLADR- and CD34+HLADR+ cultures, respectively). Our data suggest that BM stromas are not necessary for NK cell development and that IL-2 remains essential for this lineage development and differentiation.