Long-Term Results of High-Dose Therapy and Autologous Stem Cell Transplantation for Mantle Cell Lymphoma: Effectiveness of Maintenance Rituximab.

High-dose therapy followed by autologous stem cell transplantation (ASCT) can improve outcomes for mantle cell lymphoma (MCL) but is associated with a high incidence of relapse. A retrospective study of 191 MCL patients who underwent ASCT at City of Hope was performed to examine prognostic factors for outcomes after ASCT. For all patients the 5-year overall survival (OS) was 71% (95% confidence interval [CI], 63% to 77%) and progression-free survival (PFS) was 53% (95% CI, 45% to 60%). The 5-year cumulative incidence of relapse was 41% (95% CI, 34% to 48%) with a continuous pattern of relapse events occurring at a median of 2.1 years (range, .2 to 13.4) after ASCT. In multivariate analysis, post-transplant maintenance rituximab was the factor most significantly associated with both OS (relative risk [RR], .17; 95% CI, .07 to .38) and PFS (RR, .25; 95% CI, .14 to .44). For the subset of patients who had positron emission tomography (PET) data available and were in a PET-negative first complete remission at ASCT (n = 105), maintenance rituximab was significantly associated with superior OS (RR, .17; 95% CI, .05 to .59) and PFS (RR, .20; 95% CI, .09 to .43). These results support a benefit with maintenance rituximab for all MCL patients treated with ASCT.

Hyperfractionated Cyclophosphamide, Vincristine, Doxorubicin, and Dexamethasone Chemotherapy in Mantle Cell Lymphoma Patients Is Associated with Higher Rates of Hematopoietic Progenitor Cell Mobilization Failure despite Plerixafor Rescue.

Induction regimens for mantle cell lymphoma (MCL) can be categorized into highly intensive regimens containing cytarabine and less intense regimens, such as rituximab, cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone (R-CHOP) or rituximab with bendamustine (R-bendamustine). Prior publications have shown rituximab and hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone (R-hyperCVAD) can be associated with stem cell mobilization failures. However, those studies did not include the use of plerixafor as rescue for stem cell mobilization failure. We examined our database of 181 consecutive MCL patients who received upfront therapy from 2005 to 2015 with either R-hyperCVAD or less intense chemotherapy (R-bendamustine and R-CHOP only) regimens to assess impact of frontline chemotherapy on collection of hematopoietic cell progenitors before autologous stem cell transplantation (ASCT). In the preplerixafor era (before August 16, 2009), a significant difference in peripheral blood stem cell (PBSC) collection failure between the R-hyperCVAD (12%) and other chemotherapy (11%) groups was not established. However, in the postplerixafor era, use of R-hyperCVAD chemotherapy was associated with significantly higher rates of hematopoietic progenitor cell collection failures (17%) compared with that observed in the other chemotherapy group (4%; P = .04). The rates of mobilization failure declined to 4% in the postplerixafor era from 11% in the preplerixafor era for patients receiving less intensive chemotherapy. Conversely, the rate of mobilization failure increased in the R-hyperCVAD group from 12% in the preplerixafor era to 17% in the postplerixafor era. Plerixafor does not overcome the negative impact of R-hyperCVAD on PBSC mobilization, and caution is warranted in using R-hyperCVAD in patients with newly diagnosed MCL who are candidates for ASCT.

Cytomegalovirus sinusitis complicated by orbital apex syndrome in an immunocompromised host.

Sinusitis in immunocompromised patients can be caused by a wide variety of pathogens, primarily bacterial and fungal in nature. Tissue invasion can extend into the orbital apex and result in ophthalmoplegia and blindness. We report the first histologically proven case, to our knowledge, caused by cytomegalovirus infection.

The Swi3 protein plays a unique role in regulating respiration in eukaryotes.

Recent experimental evidence increasingly shows that the dysregulation of cellular bioenergetics is associated with a wide array of common human diseases, including cancer, neurological diseases and diabetes. Respiration provides a vital source of cellular energy for most eukaryotic cells, particularly high energy demanding cells. However, the understanding of how respiration is globally regulated is very limited. Interestingly, recent evidence suggests that Swi3 is an important regulator of respiration genes in yeast. In this report, we performed an array of biochemical and genetic experiments and computational analysis to directly evaluate the function of Swi3 and its human homologues in regulating respiration. First, we showed, by computational analysis and measurements of oxygen consumption and promoter activities, that Swi3, not Swi2, regulates genes encoding functions involved in respiration and oxygen consumption. Biochemical analysis showed that the levels of mitochondrial respiratory chain complexes were substantially increased in Δswi3 cells, compared with the parent cells. Additionally, our data showed that Swi3 strongly affects haem/oxygen-dependent activation of respiration gene promoters whereas Swi2 affects only the basal, haem-independent activities of these promoters. We found that increased expression of aerobic expression genes is correlated with increased oxygen consumption and growth rates in Δswi3 cells in air. Furthermore, using computational analysis and RNAi knockdown, we showed that the mammalian Swi3 BAF155 and BAF170 regulate respiration in HeLa cells. Together, these experimental and computational data demonstrated that Swi3 and its mammalian homologues are key regulators in regulating respiration.

Impact of Additional Cytogenetic Abnormalities in Adults with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia Undergoing Allogeneic Hematopoietic Cell Transplantation.

The occurrence of additional cytogenetic abnormalities (ACAs) is common in Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) but is of unknown significance in the tyrosine kinase inhibitor (TKI) era. We retrospectively analyzed data from a consecutive case series of adults with Ph+ ALL who had undergone allogeneic hematopoietic cell transplantation (alloHCT) at City of Hope between 2003 and 2014. Among 130 adults with Ph+ ALL who had TKI therapy before alloHCT, 78 patients had available data on conventional cytogenetics at diagnosis and were eligible for outcomes analysis. ACAs were observed in 41 patients (53%). There were no statistically significant differences in median age, median initial WBC count, post-HCT TKI maintenance, or disease status at the time of transplant between the Ph-only and ACA cohorts; however, the Ph-only cohort had a higher rate of minimal residual disease positivity at the time of HCT. Three-year leukemia-free survival (79.8% versus 39.5%, P = .01) and 3-year overall survival (83% versus 45.6%, P = .02) were superior in the Ph-only cohort compared with the ACA cohort, respectively. Monosomy 7 was the most common additional aberration observed in our ACA cohort (n = 12). Thus, when TKI therapy and alloHCT are used as part of adult Ph+ ALL therapy, the presence of ACAs appears to have a significant deleterious effect on outcomes post-HCT.

Enhanced heme function and mitochondrial respiration promote the progression of lung cancer cells.

Lung cancer is the leading cause of cancer-related mortality, and about 85% of the cases are non-small-cell lung cancer (NSCLC). Importantly, recent advance in cancer research suggests that altering cancer cell bioenergetics can provide an effective way to target such advanced cancer cells that have acquired mutations in multiple cellular regulators. This study aims to identify bioenergetic alterations in lung cancer cells by directly measuring and comparing key metabolic activities in a pair of cell lines representing normal and NSCLC cells developed from the same patient. We found that the rates of oxygen consumption and heme biosynthesis were intensified in NSCLC cells. Additionally, the NSCLC cells exhibited substantially increased levels in an array of proteins promoting heme synthesis, uptake and function. These proteins include the rate-limiting heme biosynthetic enzyme ALAS, transporter proteins HRG1 and HCP1 that are involved in heme uptake, and various types of oxygen-utilizing hemoproteins such as cytoglobin and cytochromes. Several types of human tumor xenografts also displayed increased levels of such proteins. Furthermore, we found that lowering heme biosynthesis and uptake, like lowering mitochondrial respiration, effectively reduced oxygen consumption, cancer cell proliferation, migration and colony formation. In contrast, lowering heme degradation does not have an effect on lung cancer cells. These results show that increased heme flux and function are a key feature of NSCLC cells. Further, increased generation and supply of heme and oxygen-utilizing hemoproteins in cancer cells will lead to intensified oxygen consumption and cellular energy production by mitochondrial respiration, which would fuel cancer cell proliferation and progression. The results show that inhibiting heme and respiratory function can effectively arrest the progression of lung cancer cells. Hence, understanding heme function can positively impact on research in lung cancer biology and therapeutics.

Pathways analysis of differential gene expression induced by engrafting doses of total body irradiation for allogeneic bone marrow transplantation in mice.

A major challenge in allogeneic bone marrow (BM) transplantation is overcoming engraftment resistance to avoid the clinical problem of graft rejection. Identifying gene pathways that regulate BM engraftment may reveal molecular targets for overcoming engraftment barriers. Previously, we developed a mouse model of BM transplantation that utilizes recipient conditioning with non-myeloablative total body irradiation (TBI). We defined TBI doses that lead to graft rejection, that conversely are permissive for engraftment, and mouse strain variation with regards to the permissive TBI dose. We now report gene expression analysis, using Agilent Mouse 8x60K microarrays, in spleens of mice conditioned with varied TBI doses for correlation to the expected engraftment phenotype. The spleens of mice given engrafting doses of TBI, compared with non-engrafting TBI doses, demonstrated substantially broader gene expression changes, significant at the multiple testing-corrected P <0.05 level and with fold change ≥2. Functional analysis revealed significant enrichment for a down-regulated canonical pathway involving B-cell development. Genes enriched in this pathway suggest that suppressing donor antigen processing and presentation may be pivotal effects conferred by TBI to enable engraftment. Regardless of TBI dose and recipient mouse strain, pervasive genomic changes related to inflammation was observed and reflected by significant enrichment for canonical pathways and association with upstream regulators. These gene expression changes suggest that macrophage and complement pathways may be targeted to overcome engraftment barriers. These exploratory results highlight gene pathways that may be important in mediating BM engraftment resistance.

Fine mapping of the Bmgr5 quantitative trait locus for allogeneic bone marrow engraftment in mice.

To identify novel mechanisms regulating allogeneic hematopoietic cell engraftment, we used forward genetics and previously described identification, in mice, of a bone marrow (BM) engraftment quantitative trait locus (QTL), termed Bmgr5. This QTL confers dominant and large allele effects for engraftment susceptibility. It was localized to chromosome 16 by quantitative genetic techniques in a segregating backcross bred from susceptible BALB.K and resistant B10.BR mice. We now report verification of the Bmgr5 QTL using reciprocal chromosome 16 consomic strains. The BM engraftment phenotype in these consomic mice shows that Bmgr5 susceptibility alleles are not only sufficient but also indispensable for conferring permissiveness for allogeneic BM engraftment. Using panels of congenic mice, we resolved the Bmgr5 QTL into two separate subloci, termed Bmgr5a (Chr16:14.6-15.8 Mb) and Bmgr5b (Chr16:15.8-17.6 Mb), each conferring permissiveness for the engraftment phenotype and both fine mapped to an interval amenable to positional cloning. Candidate Bmgr5 genes were then prioritized using whole exome DNA sequencing and microarray gene expression data. Further studies are warranted to elucidate the genetic interaction between the Bmgr5a and Bmgr5b QTL and identify causative genes and underlying gene variants. This may lead to new approaches for overcoming the problem of graft rejection in clinical hematopoietic cell transplantation.

The nuclear localization of SWI/SNF proteins is subjected to oxygen regulation.

BACKGROUND: Hypoxia is associated with many disease conditions in humans, such as cancer, stroke and traumatic injuries. Hypoxia elicits broad molecular and cellular changes in diverse eukaryotes. Our recent studies suggest that one likely mechanism mediating such broad changes is through changes in the cellular localization of important regulatory proteins. Particularly, we have found that over 120 nuclear proteins with important functions ranging from transcriptional regulation to RNA processing exhibit altered cellular locations under hypoxia. In this report, we describe further experiments to identify and evaluate the role of nuclear protein relocalization in mediating hypoxia responses in yeast. RESULTS: To identify regulatory proteins that play a causal role in mediating hypoxia responses, we characterized the time courses of relocalization of hypoxia-altered nuclear proteins in response to hypoxia and reoxygenation. We found that 17 nuclear proteins relocalized in a significantly shorter time period in response to both hypoxia and reoxygenation. Particularly, several components of the SWI/SNF complex were fast responders, and analysis of gene expression data show that many targets of the SWI/SNF proteins are oxygen regulated. Furthermore, confocal fluorescent live cell imaging showed that over 95% of hypoxia-altered SWI/SNF proteins accumulated in the cytosol in hypoxic cells, while over 95% of the proteins were nuclear in normoxic cells, as expected. CONCLUSIONS: SWI/SNF proteins relocalize in response to hypoxia and reoxygenation in a quick manner, and their relocalization likely accounts for, in part or in whole, oxygen regulation of many SWI/SNF target genes.

Over-expression of CKS1B activates both MEK/ERK and JAK/STAT3 signaling pathways and promotes myeloma cell drug-resistance.

Here we demonstrate the crucial role of CKS1B in multiple myeloma (MM) progression and define CKS1B-mediated SKP2/p27(Kip1)-independent down-stream signaling pathways. Forced-expression of CKS1B in MM cells increased cell multidrug-resistance. CKS1B activates STAT3 and MEK/ERK pathways. In contrast, SKP2 knockdown or p27(Kip1) over-expression resulted in activation of the STAT3 and MEK/ERK pathways. Further investigations showed that BCL2 is a downstream target of MEK/ERK signaling. Stimulation of STAT3 and MEK/ERK signaling pathways partially abrogated CKS1B knockdown induced MM cell death and growth inhibition. Targeting STAT3 and MEK/ERK signaling pathways by specific inhibitors induced significant MM cell death and growth inhibition in CKS1B-overexpressing MM cells and their combinations resulted in synergy. Thus, our findings provide a rationale for targeting STAT3 and MEK/ERK/BCL2 signaling in aggressive CKS1B-overexpressing MM.

Salvage allogeneic hematopoietic cell transplantation with fludarabine and low-dose total body irradiation after rejection of first allografts.

We summarized results in 38 consecutive patients (median age=56 years) with hematologic malignancies (n=35), aplastic anemia (n=2), or renal cell carcinoma (n=1), who underwent salvage hematopoietic cell transplantation (HCT) for allograft rejection. In 14 patients, the original donors were used for salvage HCT, and, in 24 cases, different donors were used. Conditioning for salvage HCT consisted of fludarabine (Flu) and either 3 or 4 Gy total body irradiation (TBI). Sustained engraftment was achieved in 33 patients (87%). Grafts were rejected in 5 patients (13%), 4 of whom had myelofibrosis. With a median follow-up of 2 years (range: 0.3 to 7.8 years), the 2- and 4-year estimated survivals were 49% and 42%, respectively. The 2-year relapse rate and nonrelapse mortality (NRM) were 36% and 24%, respectively. The 2-year cumulative incidences of grades II-IV acute and moderate-severe chronic graft-versus-host disease (aGVHD, cGVHD) were 42% and 41%, respectively. In this cohort, TBI dose, grafts from original versus different donors, related versus unrelated donors, and HCT comorbidity scores did not have an impact on outcomes. We concluded that graft rejection after allogeneic HCT could be overcome by salvage transplantation using conditioning with Flu and low-dose TBI.

Identification of a major susceptibility locus for lethal graft-versus-host disease in MHC-matched mice.

Graft-vs-host disease (GVHD) is the major cause of morbidity and mortality after allogeneic hemopoietic cell transplantation. From a genetic perspective, GVHD is a complex phenotypic trait. Although it is understood that susceptibility results from interacting polymorphisms of genes encoding histocompatibility Ags and immune regulatory molecules, a detailed and integrative understanding of the genetic background underlying GVHD remains lacking. To gain insight regarding these issues, we performed a forward genetic study. A MHC-matched mouse model was used in which irradiated recipient BALB.K and B10.BR mice demonstrate differential susceptibility to lethal GHVD when transplanted using AKR/J donors. Assessment of GVHD in (B10.BR x BALB.K)F(1) mice revealed that susceptibility is a dominant trait and conferred by deleterious alleles from the BALB.K strain. To identify the alleles responsible for GVHD susceptibility, a genome-scanning approach was taken using (B10.BR x BALB.K)F(1) x B10.BR backcross mice as recipients. A major susceptibility locus, termed the Gvh1 locus, was identified on chromosome 16 using linkage analysis (logarithm of the odds, 9.1). A second locus was found on chromosome 13, named Gvh2, which had additive but protective effects. Further identification of Gvh genes by positional cloning may yield new insight into genetic control mechanisms regulating GVHD and potentially reveal novel approaches for effective GVHD therapy.

A chromosome 16 quantitative trait locus regulates allogeneic bone marrow engraftment in nonmyeloablated mice.

Identifying genes that regulate bone marrow (BM) engraftment may reveal molecular targets for overcoming engraftment barriers. To achieve this aim, we applied a forward genetic approach in a mouse model of nonmyeloablative BM transplantation. We evaluated engraftment of allogeneic and syngeneic BM in BALB.K and B10.BR recipients. This allowed us to partition engraftment resistance into its intermediate phenotypes, which are firstly the immune-mediated resistance and secondly the nonimmune rejection of donor BM cells. We observed that BALB.K and B10.BR mice differed with regard to each of these resistance mechanisms, thereby providing evidence that both are under genetic control. We then generated a segregating backcross (n = 200) between the BALB.K and B10.BR strains to analyze for genetic linkage to the allogeneic BM engraftment phenotype using a 127-marker genome scan. This analysis identified a novel quantitative trait locus (QTL) on chromosome 16, termed Bmgr5 (logarithm of odds 6.4, at 11.1 cM). The QTL encodes susceptibility alleles, from the BALB.K strain, that are permissive for allogeneic BM engraftment. Further identification of Bmgr5 genes by positional cloning may reveal new and effective approaches for overcoming BM engraftment obstacles.

Modulation of peripheral B cell tolerance by CD72 in a murine model.

OBJECTIVE: B cells play a dominant role in the pathogenesis of several autoimmune diseases, including systemic lupus erythematosus. It is not well understood how B cell signaling contributes to autoantibody production. The goal of this study was to elucidate the role of CD72 in modulating B cell receptor (BCR)-mediated tolerogenic signaling and peripheral B cell tolerance. METHODS: A mouse model utilizing hen egg lysozyme (HEL) "anergic" B cells was studied. CD72-deficient mice carrying the BCR-specific IgHEL and/or soluble HEL (sHEL) transgenes were generated by breeding IgHEL-transgenic MD4 mice and/or sHEL-transgenic ML5 mice with congenic, CD72-deficient C57BL/6J mice. Normal and anergic B cells were isolated for analyses of B cell signaling. Aged wild-type and CD72-deficient mice were also examined for autoimmune phenomena. RESULTS: In the absence of CD72, anergic B cells inappropriately proliferated and survived in response to stimulation with self antigen. Biochemical analyses indicated that in anergic B cells, CD72 dominantly down-regulated BCR signaling to limit the antigen-induced elevation in [Ca2+]i and the activation of NFATc1, NF-kappaB, MAPK, and Akt. Mechanistically, CD72 was associated with, and regulated, the molecular adaptor Cbl-b in anergic B cells, suggesting that Cbl-b may play a role in mediating the negative effects of CD72 on BCR signaling. Moreover, in aged CD72-deficient mice, spontaneous production of antinuclear and anti-double-stranded DNA autoantibodies and features of lupus-like autoimmune disease were observed. CONCLUSION: CD72 is required to maintain B cell anergy and functions as a regulator of peripheral B cell tolerance. Thus, altered CD72 expression may play a role during the development of systemic lupus erythematosus.

Stilbene derivatives that are colchicine-site microtubule inhibitors have antileukemic activity and minimal systemic toxicity.

Stilbenes are a group of natural compounds with many biological activities. Two highly potent stilbenes, cis-3,4',5-trimethoxy-3'-aminostilbene (stilbene 5c) and cis-3,4',5-trimethoxy-3'-hydroxystilbene (stilbene 6c) induce G2/M cell-cycle arrest and leukemic cell death in nanomolarity range without affecting normal bone marrow progenitor cells. The mechanism of stilbenes is mediated by interfering with microtubule polymerization through the colchicine-binding site. Docking of the stilbenes into tubulin structure confirms that stilbenes fit into the colchicine-binding pocket. Animal studies show that stilbenes are well tolerated in mice and are capable of inducing more than 50% leukemic cell death by a single dose injection. A 5-day treatment with low-dose stilbenes suppresses tumor growth in mice with established tumor xenografts. No major organ damage was detected by histological section. Our results indicate that stilbene 5c is a microtubule-interfering agent and can be potentially useful in leukemic therapy.

Penumbra encodes a novel tetraspanin that is highly expressed in erythroid progenitors and promotes effective erythropoiesis.

In a search for new genes involved in the regulation of erythropoiesis, we identified murine Penumbra cDNA from a multipotent hematopoietic cell line based on its predominant expression in erythroblasts. Subsequently, we identified the human PENUMBRA from a bone marrow cDNA library. Penumbra is a new member of the tetraspanin superfamily of membrane proteins, many of which are thought to function as organizers of supramolecular signaling complexes. Human and murine Penumbras contain 283 amino acids and are 97% identical. The human PENUMBRA gene is mapped to chromosome 7q32, a hot spot for deletions in myelodysplastic syndromes and acute myelogenous leukemias. Penumbra is targeted to the cell surface and forms disulfide-bonded homodimers. To study the effects of Penumbra deletions, we created a knockout mouse model by gene targeting. Penumbra(-/-) mice develop massive splenomegaly, basophilic macrocytic red blood cells, and anemia as they age. A multipotent hematopoietic cell line, EMX, was established from the bone marrow of a Penumbra(-/-) mouse. EMX exhibits ineffective erythropoiesis in the presence of erythropoietin, a defect that is reversed by reexpression of Penumbra. These findings indicate that Penumbra has a positive function in erythropoiesis and its deletion or mutation may result in anemia.

Silencing human NKG2D, DAP10, and DAP12 reduces cytotoxicity of activated CD8+ T cells and NK cells.

Human CD8+ T cells activated and expanded by TCR cross-linking and high-dose IL-2 acquire potent cytolytic ability against tumors and are a promising approach for immunotherapy of malignant diseases. We have recently reported that in vitro killing by these activated cells, which share phenotypic and functional characteristics with NK cells, is mediated principally by NKG2D. NKG2D is a surface receptor that is expressed by all NK cells and transmits an activating signal via the DAP10 adaptor molecule. Using stable RNA interference induced by lentiviral transduction, we show that NKG2D is required for cytolysis of tumor cells, including autologous tumor cells from patients with ovarian cancer. We also demonstrated that NKG2D is required for in vivo antitumor activity. Furthermore, both activated and expanded CD8+ T cells and NK cells use DAP10. In addition, direct killing was partially dependent on the DAP12 signaling pathway. This requirement by activated and expanded CD8+ T cells for DAP12, and hence stimulus from a putative DAP12-partnered activating surface receptor, persisted when assayed by anti-NKG2D Ab-mediated redirected cytolysis. These studies demonstrated the importance of NKG2D, DAP10, and DAP12 in human effector cell function.

CD34, CD4, and CD8 cell doses do not influence engraftment, graft-versus-host disease, or survival following myeloablative human leukocyte antigen-identical peripheral blood allografting for hematologic malignancies.

OBJECTIVES: Optimal granulocyte colony-stimulating factor-mobilized peripheral blood progenitor cell (G-PBMC) graft compositions for myeloablative allogeneic hematopoietic cell transplantation (AHCT) have not been identified. G-PBMC cell contents were analyzed for influence on outcomes. PATIENTS AND METHODS: Human leukocyte antigen(HLA)-identical related donor AHCT was used to treat 101 patients with hematologic malignancies at a single institution between 1995 and 2002. CD34+, CD3+, CD4+, and CD8+ cell doses were enumerated by flow cytometry and evaluated by univariate analysis. RESULTS: Categorized by the median of cell doses infused, no G-PBMC cell dose significantly correlated with neutrophil and platelet engraftment. Incidence of grade II to IV acute graft-versus-host disease (GVHD) was 24.6% (95% confidence interval [CI]: 15.9-33.3) and was not significantly influenced by evaluated G-PBMC cell doses. With a median follow-up time of 18 months for surviving patients, estimates for extensive chronic GVHD was 43.8% (95% CI: 31.4-56.2), for freedom from progression was 69.5% (95% CI: 58.1-80.9), and for overall survival was 46.9% (95% CI: 35.5-58.3). CD34+, CD3+, CD4+, and CD8+ cell doses were not significantly predictive of extensive chronic GVHD, freedom from progression or overall survival. Additionally, comparing patients receiving the upper versus lower 33rd percentiles of CD34+ cell dose, associations with extensive chronic GVHD remained insignificant (p=0.21; relative risk (RR)=1.7; 95% CI: 0.7-3.9). CONCLUSIONS: G-PBMC graft content does not influence outcomes after myeloablative AHCT. In particular, no significant association between extensive chronic GVHD was identified with any G-PBMC cell dose, including CD34.

Cytokines and cytotoxic pathways in engraftment resistance to purified allogeneic hematopoietic stem cells.

The way that allogeneic hematopoietic cells are rejected is not completely understood. Regimen-resistant populations, including natural killer (NK) cells and lymphocytes, are thought to mediate the allograft barrier. In this report, the mechanism by which recipient cell populations resist engraftment of purified allogeneic hematopoietic stem cells (HSCs) was examined in mice. To define the immunoregulatory pathways involved in allogeneic hematopoietic cell resistance, HSC transplantations were performed in immune-defective recipients. Recipients were wild-type mice treated with alpha-NK cell antibodies or knockout strain mice lacking expression of CD8, perforin, Fas ligand, or 1 of the following cytokines: tumor necrosis factor alpha, transforming growth factor beta, interferon gamma, interleukin 4, or interleukin 10. Elimination of a single cytotoxic pathway was ineffective in reducing engraftment resistance, although mice treated with a polyclonal antibody that recognizes NK-cell determinants or CD8 expression showed a profound reduction in the engraftment barrier. Posttransplantation chimerism analysis revealed regeneration of host hematopoiesis in some experimental groups. These studies show, for the first time, that elimination of selected cytokines does not alter allogeneic hematopoietic resistance. Furthermore, the chimerism data reinforce the importance of competition for HSC niches in conjunction with immune mechanisms in resistance to long-term HSC engraftment.

Single infusion of myeloid progenitors reduces death from Aspergillus fumigatus following chemotherapy-induced neutropenia.

Hematopoietic progenitors committed to the myeloid lineage, the common myeloid and granulocyte-monocyte progenitors (CMP/GMP), have been shown to protect against opportunistic pathogens following myeloablative radiation; however, the efficacy of this approach has not been studied in the setting of chemotherapy-induced neutropenia. In this mouse model, the infusion of CMP/GMP on the day after 5-fluorouracil (5-FU) administration (D+1) resulted in a significant increase in the number of splenic neutrophils by D+8 when compared with 5-FU-only controls (P = .02), the majority of which were CMP/GMP-derived (54%). Moreover, 19% and 28% of neutrophils in the blood and bone marrow, respectively, were CMP/GMP-derived. Survival following intranasal challenge with the fungus Aspergillus fumigatus was significantly higher in CMP/GMP-infused mice than the controls (56% and 33% respectively; P = .019). Thus, a single infusion of CMP/GMP enhances tissue neutrophil content and increases survival against a lethal challenge with A fumigatus in the setting of chemotherapy-induced neutropenia.