Decreased plasma cytokines are associated with low platelet counts in aplastic anemia and immune thrombocytopenic purpura

BACKGROUND

We previously found plasma levels of CD40 ligand (CD40L), chemokine (C-X-C motif) ligand 5 (CXCL5), chemokine (C-C motif) ligand 5 (CCL5) and epidermal growth factor (EGF) to be low in aplastic anemia (AA) patients and to be correlated with platelet count.

OBJECTIVES

To study the association of CD40L, CXCL5, CCL5 and EGF with platelets.

METHODS

We measured cytokines in the plasma of immune thrombocytopenic purpura (ITP) and AA patients using the Luminex assay and confirmed the results in a mouse model and in vitro experiments.

RESULTS

Both ITP and AA showed similarly low levels of CD40L, CXCL5, CCL5 and EGF, compared with healthy controls. In ITP, levels of these proteins were significantly greater in patients with higher platelet counts than in those with lower platelet counts. In a murine thrombocytopenia model, levels of CD40L, CXCL5, CCL5 and EGF decreased with platelet count after immune-mediated destruction, while the cytokine levels increased when the platelet count recovered. In vitro, concentrations of these cytokines in the supernatants of platelet suspensions were proportional to platelet numbers, and levels in sera prepared by simple blood coagulation were equivalent to those in platelet-rich plasma-converted sera. mRNA expression for CXCL5, CCL5 and EGF was higher in platelets than in megakaryocytes, peripheral blood mononuclear cells, granulocytes and non-megakaryocytic bone marrow cells.

CONCLUSIONS

Plasma CD40L, CXCL5, CCL5 and EGF are mainly platelet-derived, suggesting a role of platelets in immune responses and inflammation. Measurement of CD40L, CXCL5, CCL5 and EGF in human blood allowed testable inferences concerning physiology and pathophysiology in quantitative platelet disorders.

Erosion of telomeric single-stranded overhang in patients with aplastic anaemia carrying telomerase complex mutations

BACKGROUND

Loss-of-function mutations in telomerase complex genes reduce telomerase activity and shorten overall telomere length in leucocytes, and they can clinically manifest as bone marrow failure (aplastic anaemia and dyskeratosis congenita) and familial pulmonary fibrosis. Telomeres are constituted of double-stranded tandem TTAGGG repeats followed by a 3' G-rich single-stranded overhang, a crucial telomeric structural component responsible for the t-loop formation.

MATERIALS AND METHODS

We investigated the length of telomeric overhangs in 25 healthy individuals from 0 to 76 years of age, 16 patients with aplastic anaemia, and 13 immediate relatives using a non-denaturing in-gel method and the telomere-oligonucleotide ligation assay.

RESULTS

Telomeric overhang lengths were constant from birth to eighth decade of life in healthy subjects, in contrast to overall telomere length, which shortened with ageing. Most patients with marrow failure and a telomerase gene mutation showed marked erosion of telomeric overhang associated with critically short telomeres; in other aplastic patients with normal genotypes, normal overall telomere lengths and who responded to immunosuppressive therapy, telomeric overhangs were maintained.

CONCLUSIONS

Telomeric overhang erosion does not participate in physiological ageing but support a role for eroded telomeric overhangs and abnormal telomere structure in pathological shortening of telomeres, especially caused by loss-of-function telomerase mutations. Disrupted telomere structure caused by short telomeric overhangs may contribute to the mechanisms of abnormal haematopoietic compartment senescence and chromosomal instability in human bone marrow failure.

Drugs in the aetiology of agranulocytosis and aplastic anaemia

Agranulocytosis and aplastic anaemia are rare but serious conditions known to be caused by numerous drugs. Most of what is known or suspected about the aetiology is based on case reports, with only a few formal epidemiological studies that provide quantitative estimates of risk. Updated results have been obtained from a combined analysis of data from 3 case-control studies that used similar methods: the International Agranulocytosis and Aplastic Anemia Study (IAAAS), conducted in Israel and Europe; a study conducted in the northeast US; and a study conducted in Thailand. Totals of 362 cases of agranulocytosis, 454 cases of aplastic anaemia and 6458 controls were included in the analyses. The IAAAS and Thai study were population-based, providing estimates of the incidence of the 2 dyscrasias. The overall annual incidence of agranulocytosis in the ambulatory population was 3.4/10(6) in the IAAAS and 0.8/10(6) in Thailand; by contrast the incidence of aplastic anaemia was 2.0/10(6) in the IAAAS and 4.1/10(6) in Thailand. A total of 21 compounds were significantly associated with an increased risk of agranulocytosis in the IAAAS and US studies. Excess risks ranged from 0.06 to 13 cases/10(6) users/wk; the most strongly associated drugs were procainamide, anti-thyroid drugs and sulphasalazine. An association with drugs that had previously been suspected was also seen in Thailand. The overall aetiologic fractions of agranulocytosis due to drug use were 62% in the IAAAS, 72% in the US and 70% in Thailand. Eleven drugs were significantly associated with an increased risk of aplastic anaemia, with excess risks ranging from 1.4 to 60 cases/10(6) users in a 5-month period. The most strongly associated drugs were penicillamine, gold and carbamazepine. Aetiologic fractions were 27% in the IAAAS, 17% in the US and 2% in Thailand, which paralleled the prevalence of use of associated drugs in the 3 populations. The present results confirm that agranulocytosis is largely a drug-induced disease, with similar proportions accounted for in 3 disparate geographic regions. By contrast, although many of the expected associations were observed for aplastic anaemia, most of the aetiology is not explained by drugs. For all associated drugs, the excess risks are sufficiently low that blood dyscrasias should not figure prominently in the balancing of risks and benefits.

Immune pathophysiology of acquired aplastic anaemia

Clinical observations and laboratory studies have supported an immune basis for most acquired aplastic anaemias, with the majority of patients responding to immunosuppressive therapy. In vitro, interferon (IFN) and tumour necrosis factor (TNF) inhibit haematopoiesis, including colony formation by early and late progenitor cells and the generation of long-term culture initiating cells (LTCIC). These lymphokines induce Fas antigen expression on CD34+ cells and apoptosis within the haematopoietic cell compartment. Local secretion of cytokines is far more potent than addition to long-term bone marrow cultures. Activated cytotoxic lymphocytes, high levels of INF gamma and TNF alpha, and increased Fas expression on CD34+ marrow cells are present in patients. Haematopoiesis is severely diminished in severe aplastic anaemia on presentation: CD34+ cell numbers, colony forming cells and LTCIC are all markedly decreased. LTCIC numbers do not predict recovery. Blood cell counts increase in some cases in the absence of changed numbers of LTCIC, but recovered patients have higher and sometimes normal LTCIC numbers. The mechanism by which chemical and biological agents incite altered immunity remains unclear. Drug associations have been inferred from case reports and formal epidemiological studies, but have remained refractory to systematic laboratory study. Whatever the initial events, immune system destruction of haematopoiesis plays a central role in the development of acquired aplastic anaemia.

Patient-specific transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is one of the leading causes of transfusion-associated mortality. The inadvertent transfusion of neutrophil antibodies can cause pulmonary transfusion reactions and TRALI. However, not all patients transfused with neutrophil antibodies experience transfusion reactions. A 22-year-old man with severe aplastic anaemia (SAA) experienced TRALI after a platelet transfusion. The donor was found to be alloimmunized to human neutrophil antigen (HNA)-3a, an antigen expressed by neutrophils from approximately 90% of Caucasians. Eleven other platelet components from this donor were transfused prior to this event and two caused reactions: one chills and one TRALI. Both episodes of TRALI occurred in the same male patient with SAA. The fact that one patient experienced TRALI following both exposures to anti-HNA-3a from the same donor whereas nine other recipients did not adds evidence to the observation that patient factors make a significant contribution to neutrophil antibody-mediated transfusion reactions.

Evaluation of risk for development of myeloproliferative disorders, myelodysplastic syndromes, or acute leukemias with long-term eculizumab therapy in paroxysmal nocturnal hemoglobinuria (PNH) patients

7087

Background: PNH is a rare bone marrow failure disorder defined by stem cell clones with somatic mutations in the PIG-A gene. These mutations result in peripheral blood cells deficient in GPI-anchored proteins including complement inhibitors CD55 and CD59. Chronic lysis of PNH RBCs leads to severe anemia, life-threatening thrombosis, debilitating fatigue, and impaired quality of life. Previous studies have indicated an increased frequency of myeloproliferative disorders, MDS, and acute leukemias in PNH. In a previous retrospective analysis of 1,760 PNH patients, 6.8% developed either myeloid or lymphoid disorders and 1% developed acute leukemias. Eculizumab (Soliris) is a humanized antibody that prevents terminal complement activation. Long-term eculizumab treatment has been evaluated in 195 PNH patients (>250 patient years of exposure) and shown to significantly restore the endogenous PNH RBC clone resulting in improved anemia, as well as significant improvements in thrombosis, fatigue, and quality of life. Methods: Leukocyte clone sizes were assessed at baseline and 26 weeks for patients receiving eculizumab in the Phase III clinical trials (TRIUMPH and SHEPHERD) using flow cytometry. The frequency of MDS and leukemia was calculated as a percentage of the eculizumab-treated patients across all eculizumab trials. Results: PNH leukocyte clone size did not increase with eculizumab treatment (median 96.1% at baseline vs 95.5% at week 26; P=0.80, signed rank test) suggesting that inhibition of terminal complement does not destroy or result in the proliferation of PNH leukocyte clones. Additionally, the frequency of new MDS (1/195 patients, 0.5%) and CMML (1/195 patients, 0.5%) during the treatment period was not increased over that expected. The single case of CMML occurred in a patient previously diagnosed with and was attributed to high grade myelodysplasia. Conclusions: To date, eculizumab treatment of PNH patients does not increase the risk for the development of myeloproliferative disorders, MDS or acute leukemias. Patients on eculizumab will continue to be followed in a Global PNH Safety Registry.

No significant financial relationships to disclose.

Safety and efficacy of eculizumab in paroxysmal nocturnal hemoglobinuria evolving from patients with myelodysplastic syndrome and aplastic anemia

7033

Background: Myelodysplastic syndrome (MDS) and aplastic anemia (AA) have been reported to be associated with the development of the acquired clonal hemolytic and bone marrow failure disorder, paroxysmal nocturnal hemoglobinuria (PNH). Two recent phase 3 clinical studies have demonstrated significant benefit of the complement inhibitor eculizumab (Soliris) in a heterogeneous population of patients with PNH (n=140). Methods: To investigate whether eculizumab was safe and effective in PNH patients with a history of MDS or AA (n=37), efficacy parameters were examined in the MDS/AA patient subpopulation. Results: Intravascular hemolysis, as assessed by plasma levels of the enzyme lactate dehydrogenase (LDH), was reduced from a mean of 1871 ± 159 U/L at baseline to 300 ± 21 U/L at week 26 in patients with a history of MDS or AA (p<0.001, signed rank test; normal range 103–223 U/L). Anemia was improved as packed RBC transfusion requirements were substantially reduced with eculizumab in these patients from a median of 8 units per patient in the 6 months before treatment to 0 units per patient during eculizumab treatment (p<0.001, signed rank test). Despite history of bone marrow failure, eculizumab treatment markedly improved fatigue with an 11.6 point increase over baseline using the FACIT-Fatigue instrument (p<0.001, signed rank test; a 3 or more point increase in this instrument has been shown to be clinical meaningful). Fatigue was similarly improved with the fatigue scale of the EORTC QLQ-C30 instrument (p<0.001, signed rank test). Eculizumab appeared to be well tolerated when administered to PNH patients with a history of MDS or AA. The significant clinical improvements in hematologic and quality of life outcomes with eculizumab treatment in PNH patients with a history of MDS or AA were similar to the clinical improvements demonstrated the overall PNH patient population. Conclusions: These analyses show that eculizumab treatment may provide important clinical benefit when administered to PNH patients with a history of bone marrow failure.

No significant financial relationships to disclose.

Safety and efficacy of eculizumab with concomitant erythropoietin therapy in patients with paroxysmal nocturnal hemoglobinuria (PNH)

3032

Background: Erythropoietins (EPO) are commonly used to improve anemia in patients with bone marrow failure syndromes and in patients with chemotherapy-induced anemia. Two recent phase 3 clinical studies have demonstrated significant benefit of the terminal complement inhibitor, eculizumab (Soliris), in a heterogeneous population of patients with the acquired clonal hemolytic and bone marrow failure disorder, PNH (n=140). While previous studies have shown that EPO is associated with only moderate improvements in fatigue in anemic cancer patients (effect size of 0.5), eculizumab has demonstrated large improvements in fatigue in PNH patients (effect size of 1.1). Methods: To investigate whether eculizumab provides further benefit to PNH patients receiving EPO, efficacy parameters were examined in the EPO subpopulation (n=8). Results: Intravascular hemolysis, as assessed by plasma levels of lactate dehydrogenase (LDH) area under the curve, was reduced 268,271 U/L x day to near normal levels in EPO-treated patients during 26 weeks of eculizumab therapy (p=0.008, signed rank test). Anemia was improved as packed RBC transfusion requirements were substantially reduced with eculizumab in EPO patients from a median of 7.5 units per patient in the 6 months before treatment to 1 unit per patient during eculizumab treatment (p=0.031, signed rank test). Despite pre-existing EPO and transfusion support, eculizumab treatment markedly improved fatigue with a 7.3 point increase over baseline using the FACIT-fatigue instrument (p=0.016, signed rank test; a 3 or more point increase in this instrument has been shown to be clinically meaningful). Eculizumab was well tolerated when administered to PNH patients treated with concomitant EPO with adverse events similar to the overall population. The significant clinical improvements in hematologic and quality of life outcomes with eculizumab treatment in PNH patients receiving concomitant EPO were similar to the clinical improvements demonstrated in the overall PNH patient population. Conclusions: These analyses show that eculizumab treatment provides important clinical benefit when administered to PNH patients receiving EPO support for bone marrow failure.

No significant financial relationships to disclose.

Brief report: no evidence for parvovirus B19 or hepatitis E virus as a cause of acute liver failure

Viral hepatitis A and B are known to cause acute liver failure. While nearly 20% of acute liver failure cases are of indeterminate etiology, screening for other viruses has not been uniformly performed. We looked for evidence for parvovirus B19 and hepatitis E virus in sera from U.S. acute liver failure patients. For B19, 78 patients' sera, including 34 with indeterminate etiology, were evaluated by DNA dot-blot hybridization, reverse transcription polymerase chain reaction, and enzyme-linked immunosorbent assay for immunoglobin G and M antibodies; none showed evidence for infection.

Differential gene expression in hematopoietic progenitors from paroxysmal nocturnal hemoglobinuria patients reveals an apoptosis/immune response in 'normal' phenotype cells

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired stem cell disorder characterized clinically by intravascular hemolysis, venous thrombosis, and bone marrow failure. Despite elucidation of the biochemical and molecular defects in PNH, the pathophysiology of clonal expansion of glycosylphosphatidylinositol-anchored protein (GPI-AP)-deficient cells remains unexplained. In pursuit of evidence of differences between GPI-AP-normal and -deficient CD34 cells, we determined gene expression profiles of isolated marrow CD34 cells of each phenotype from PNH patients and healthy donors, using DNA microarrays. Pooled and individual patient samples revealed consistent gene expression patterns relative to normal controls. GPI-AP-normal cells from PNH patients showed upregulation of genes involved in apoptosis and the immune response. Conversely, genes associated with antiapoptotic function and hematopoietic cell proliferation and differentiation were downregulated in these cells. In contrast, the PNH clone of GPI-AP-deficient cells appeared more similar to CD34 cells of healthy individuals. Gene chip data were confirmed by other methods. Similar gene expression patterns were present in PNH that was predominantly hemolytic as in PNH associated with aplastic anemia. Our results implicate an environmental influence on hematopoietic cell proliferation, in which the PNH clone evades immune attack and destruction, while normal cells suffer a stress response followed by programmed cell death.

Large granular lymphocyte (LGL)-like clonal expansions in paroxysmal nocturnal hemoglobinuria (PNH) patients

In paroxysmal nocturnal hemoglobinuria (PNH), clonal expansion of glycosylphosphatidylinositol-anchored proteins (GPI-AP)-deficient cells leads to a syndrome characterized by hemolytic anemia, marrow failure, and venous thrombosis. PNH is closely related to aplastic anemia and may share its immune pathophysiology. In vivo expansion of dominant T-cell clones can reflect an antigen-driven immune response but may also represent autonomous proliferation, such as in large granular lymphocytic (LGL)-leukemia. T-cell clonality can be assessed by a combination of T-cell receptor (TCR) flow cytometry and complementarity-determining-region-3 (CDR3) molecular analysis. We studied 24 PNH patients for evidence of in vivo dominant T-cell responses by flow cytometry; TCR-Vbeta-specific expansions were identified in all patients. In four cases, extreme expansions of one Vbeta-subset of CD8+/CD28-/CD56+ (effector) phenotype mimicked subclinical LGL-disease. The monoclonality of these expansions was inferred from unique CDR3-size peak distributions and sequencing of dominant clonotypes. We conclude that the molecular analysis of TCR-beta chain may demonstrate clonal LGL-like expansions at unexpected frequency in PNH patients. Our observations blur the classical boundaries between different bone marrow failure syndromes such as AA, PNH, and LGL, and support the hypothesis that in PNH, the mutant clone may expand as a result of an immune-escape from antigen-driven lymphocyte attack on hematopoietic progenitors.

The graft-versus-leukemia effect of nonmyeloablative stem cell allografts may not be sufficient to cure chronic myelogenous leukemia

We treated 12 patients with chronic myelogenous leukemia (CML) with a low-intensity preparative regimen followed by allogeneic stem cell transplantation in an attempt to confer a curative graft-versus-leukemia (GVL) effect with minimum morbidity. Seven patients in first chronic phase (CP1) and five in second chronic phase (CP2) (age 15-68 years) received a nonmyeloablative conditioning regimen of fludarabine and cyclophosphamide, followed by a G-CSF-mobilized peripheral blood stem cell (PBSC) transplant from an HLA-identical sibling. Cyclosporine (CsA) was used for graft-versus-host disease (GVHD) prophylaxis. Median follow-up was 384 days. Neutrophil recovery occurred at a median of 12 days. There was no transplant-related mortality. Of the seven CP1 patients transplanted, seven achieved a stable molecular remission; two with no post-transplant intervention, three after donor lymphocytes, imatinib and interferon, and two after a myeloablative stem cell transplant. Four of five CP2 patients died in blast crisis and one survived in molecular remission. Of the 12 patients with durable engraftment, six had Grades II-IV acute GVHD; six had limited chronic GVHD. These results suggest that cytoreduction is required to optimize the curative effect of allogeneic stem cell transplantation for CML.

Cyclosporine is required to prevent severe acute GVHD following T-cell-depleted peripheral blood stem cell transplantation

Reduced immunosuppression may improve immune recovery and increase the graft-versus-leukemia effect after allogeneic stem cell transplantation. Furthermore, the requirement for post-transplant immunosuppression following extensive T-cell depletion remains unclear. We therefore evaluated the role of cyclosporine (CSA) in recipients of HLA-identical T-cell-depleted peripheral blood stem cell transplants (PBSCT), followed by donor lymphocyte infusions (DLIs) scheduled on days +45 and +100. Before day+45, successive cohorts of patients received decreasing amounts of CSA: standard-dose (SD) CSA, low-dose (LD) CSA, or no CSA until day+45. LD CSA was as effective as SD CSA in preventing acute graft-versus-host disease (GVHD). However, moderate-to-severe acute GVHD was significantly more frequent before the day +45 DLI in patients receiving no CSA (33.3 vs 12.7%, P=0.036, including the only four grade III-IV cases). As a result of higher rates of early acute GVHD, more patients in the 'no CSA' group failed to receive any DLI (30.7 vs 7.1%, P=0.01). Overall, there was no difference in the incidence of acute GVHD, as patients receiving CSA developed more GVHD after DLI. Similarly, no significant differences were found in chronic GVHD, transplant-related mortality, or survival. These results define a role for CSA in preventing GVHD at low T-cell doses following PBSCT.

Increased frequency of HLA-DR2 in patients with paroxysmal nocturnal hemoglobinuria and the PNH/aplastic anemia syndrome

Many autoimmune diseases are associated with HLA alleles, and such a relationship also has been reported for aplastic anemia (AA). AA and paroxysmal nocturnal hemoglobinuria (PNH) are related clinically, and glycophosphoinositol (GPI)-anchored protein (AP)-deficient cells can be found in many patients with AA. The hypothesis was considered that expansion of a PNH clone may be a marker of immune-mediated disease and its association with HLA alleles was examined. The study involved patients with a primary diagnosis of AA, patients with myelodysplastic syndrome (MDS), and patients with primary PNH. Tests of proportions were used to compare allelic frequencies. For patients with a PNH clone (defined by the presence of GPI-AP-deficient granulocytes), regardless of clinical manifestations, there was a higher than normal incidence of HLA-DR2 (58% versus 28%; z = 4.05). The increased presence of HLA-DR2 was found in all frankly hemolytic PNH and in PNH associated with bone marrow failure (AA/PNH and MDS/PNH). HLA-DR2 was more frequent in AA/PNH (56%) than in AA without a PNH clone (37%; z = 3.36). Analysis of a second cohort of patients with bone marrow failure treated with immunosuppression showed that HLA-DR2 was associated with a hematologic response (50% of responders versus 34% of nonresponders; z = 2.69). Both the presence of HLA-DR2 and the PNH clone were independent predictors of response but the size of PNH clone did not correlate with improvement in blood count. The results suggest that clonal expansion of GPI-AP-deficient cells is linked to HLA and likely related to an immune mechanism.

Relationship between bone marrow failure syndromes and the presence of glycophosphatidyl inositol-anchored protein-deficient clones

Because of the insensitivity of the Ham test, paroxysmal nocturnal haemoglobinuria (PNH) has been inaccurately viewed as a late clonal complication of aplastic anaemia (AA). To clarify the relationship between PNH and marrow failure, we tested for the presence of glycosylphosphatidyl-anchored protein-deficient (GPI-AP) granulocytes in large cohorts of patients with AA, myelodysplasia (MDS), and pure haemolytic PNH. A PNH clone was detected in 32% of new AA patients and 18% of MDS patients. In serial studies, this proportion did not change up to 15 years after diagnosis, suggesting that expansion of aberrant cells is an early event (i.e. prior to initial presentation). For all patients with a PNH clone, on average 14% of PNH granulocytes were found on presentation and 37% at 10 years. Patients with PNH but without cytopenia showed higher percentages of GPI-AP-deficient cells than did those with the AA/PNH syndrome. After immunosuppression, there was no change in the contribution of PNH clone to blood production, arguing against the "immune-escape" theory in PNH. Clinically, a high proportion of GPI-AP-deficient cells correlated with marrow hypercellularity. GPI-AP-deficient cells were similarly present in patients with and without karyotypic abnormalities. Our results indicate that the GPI-AP-deficient clones show quantitative and kinetic differences between classic haemolytic PNH and PNH with marrow failure, in which the evolution rate is low later in the course of the disease.

Increased cytotoxic T cells with effector phenotype in aplastic anemia and myelodysplasia

OBJECTIVE

We hypothesized that an active autoimmune process in aplastic anemia (AA) corresponds to the expansion of cytotoxic lymphocytes (CTLs) displaying mature effector phenotype. We determined whether the numbers of effector CTLs in blood of patients with bone marrow failure syndromes are elevated and correlate with the disease activity and responsiveness to immunosuppression.

PATIENTS AND METHODS

We analyzed samples from patients with AA, myelodysplastic syndrome (MDS), polytransfused patients with nonimmune-mediated hematologic disease, and normal controls for the presence of effector T lymphocytes using four-color flow cytometry. Expression of CD57 and loss of CD28 on CD8+CD3+ CTL were used as markers for the terminal effector phenotype. In addition, intracellular staining for perforin and granzyme B was preformed. The numbers of effector CTL did not differ between healthy individuals and hematologic controls and the two groups were pooled.

RESULTS

The percentages of CD8+CD28- and CD8+CD28-CD57+ cells were significantly higher in AA and MDS patients than in controls. There was a trend toward a gradual decrease in the effector CTLs from the high values observed in untreated new patients and patients who did not respond to immunosuppression, intermediate levels for partial responders and complete responders, to the lowest levels seen in controls. However, severity of pancytopenia did not correlate with the size of the effector cell population. In contrast to CD57+ CTLs, expression of perforin or granzyme B in the cytotoxic effector cells did not differ in AA patients from those of controls.

CONCLUSIONS

Our results indicate that phenotypically defined effector CTLs are increased in AA and MDS and the effector phenotype may be useful to isolate and characterize antigen-specific T cells in AA in order to delineate the possible inciting or driving agents in AA.

Oral manifestations in patients with aplastic anemia

OBJECTIVE

The aim of the present study was to characterize the prevalence and risks of oral complications in aplastic anemia (AA).

STUDY DESIGN

Approximately 79 patients with AA (age, 37 +/- 17 years) and 66 control patients with schizophrenia (age, 33 +/- 12 years) were examined. Records were reviewed for demographic, clinical, and radiographic information. Prior medical therapy, laboratory values, disease duration, and medical treatment response were noted for patients with AA. Odds ratios (OR) and 95% CI were calculated for oral manifestations in cases and in control subjects. Univariate analysis identified important variables for logistic regression.

RESULTS

Patients with AA presented more frequently with oral petechiae (OR = 49; 95% CI, 2.9-825), gingival hyperplasia (OR = 27; 95% CI, 1.6-463.5), spontaneous gingival bleeding (OR = 27; 95% CI, 1.6-463.5), and herpetic lesions (OR = 27; 95% CI, 1.6-463.5). Prior cyclosporine use was associated with gingival hyperplasia (P =.0001). No other predictors for oral manifestations or treatment outcomes were found.

CONCLUSIONS

Oral soft tissue changes and infections were more common in patients with AA. Prior cyclosporine use was predictive of the presence of gingival hyperplasia.

Transplant dose of CD34(+) and CD3(+) cells predicts outcome in patients with haematological malignancies undergoing T cell-depleted peripheral blood stem cell transplants with delayed donor lymphocyte add-back

We sought to optimize and standardize stem cell and lymphocyte doses of T cell-depleted peripheral blood stem cell transplants (T-PBSCT), using delayed add-back of donor T cells (DLI) to prevent relapse and enhance donor immune recovery. Fifty-one patients with haematological malignancies received a T-PBSCT from an HLA-identical sibling, followed by DLI of 1 x 10(7) and 5 x 10(7) CD3(+) cells/kg on d +45 and +100 respectively. Twenty-four patients were designated as standard risk and twenty-seven patients with more advanced leukaemia were designated as high risk. Median recipient age was 38 years (range 10-56). Median (range) of CD34(+) and CD3(+) cell transplant doses were 4.6 (2.3-10.9) x 10(6)/kg and 0.83 (0.38-2) x 10(5)/kg respectively. The cumulative probability of acute GVHD was 39%. No patient died from GVHD or its consequences. The probability of developing chronic GVHD was 54% (18% extensive). The probability of relapse was 12% for the standard-risk patients and 66% for high-risk patients. In multivariate analysis, the risk factors for lower disease-free survival and overall survival were high-risk disease, CD34(+) dose < 4.6 x 10(6)/kg and CD3(+) dose < 0.83 x 10(5)/kg. Predictive factors for chronic GVHD were a T-cell dose at transplant > 0.83 x 10(5) CD3(+) cells/kg. These results further define the impact of CD34 and CD3 cell dose on transplant outcome and show that careful dosing of stem cells and lymphocytes may permit the control and optimization of transplant outcome.

Limited heterogeneity of T cell receptor BV usage in aplastic anemia

Immune mediation of aplastic anemia (AA) has been inferred from clinical responsiveness to immunosuppressive therapies and a large body of circumstantial laboratory evidence. However, neither the immune response nor the nature of the antigens recognized has been well characterized. We established a large number of CD4 and CD8 T cell clones from a patient with AA and analyzed their T cell receptor (TCR) usage. Most CD4 clones displayed BV5, whereas most CD8 clones displayed BV13. We found sequence identity for complementarity determining region 3 (CDR3) among a majority of CD4 clones; the same sequence was present in marrow lymphocytes from four other patients with AA but was not detected in controls. The dominant CD4 clone showed a Th1 secretion pattern, lysed autologous CD34 cells, and inhibited their hematopoietic colony formation. In three of four patients, successful immunosuppressive treatment led to marked decrease in clones bearing the dominant CDR3 BV5 sequence. These results suggest surprisingly limited heterogeneity of the T cell repertoire in an individual patient and similarity at the molecular level of the likely pathological lymphocyte response among multiple patients with AA, consistent with recognition of limited numbers of antigens shared by individuals with the same HLA type in this disease.

Telomere length in leukocyte subpopulations of patients with aplastic anemia

In most human cells, the average length of telomere repeats at the ends of chromosomes provides indirect information about their mitotic history. To study the turnover of stem cells in patients with bone marrow failure syndromes, the telomere length in peripheral blood granulocytes and lymphocytes from patients with aplastic anemia (AA, n = 56) and hemolytic paroxysmal nocturnal hemoglobinuria (n = 6) was analyzed relative to age-matched controls by means of fluorescence in situ hybridization and flow cytometry. The telomere lengths in granulocytes from patients with AA were found to be significantly shorter than those in age-adjusted controls (P =.001). However, surprisingly, telomere length in granulocytes from AA patients who had recovered after immunosuppressive therapy did not differ significantly from controls, whereas untreated patients and nonresponders with persistent severe pancytopenia showed marked and significant telomere shortening. These results support extensive proliferation of hematopoietic stem cells in subgroups of AA patients. Because normal individuals show significant variation in telomere length, individual measurements in blood cells from AA patients may be of limited value. Whether sequential telomere length measurements can be used as a prognostic tool in this group of disorders remains to be clarified. (Blood. 2001;97:895-900)

Coincident myelodysplastic syndrome and T-cell large granular lymphocytic disease: clinical and pathophysiological features

Myelodysplastic syndrome (MDS) and T-cell large granular lymphocytic disease (T-LGL) are bone marrow failure disorders. Successful use of immunosuppressive agents to treat cytopenia in MDS and LGL suggests a common pathophysiology for the two conditions. Of 100 patients with initial diagnoses of either MDS or T-LGL referred to the National Institutes of Health for immunosuppressive treatment of cytopenia, nine had characteristics of both T-LGL and MDS (T-LGL/MDS). Fifteen patients with T-LGL received cyclosporin (CSA) (10 responses). Eight out of nine patients with T-LGL/MDS received CSA (two responses) and one patient received ATG (one response). Of 76 patients with MDS, eight received CSA (one response) and 68 received ATG (21 responses). The response to immunosuppression was significantly lower in patients with T-LGL/MDS and MDS than in patients with T-LGL disease alone (28% vs. 66%, P = 0.01). The proportion of T-helper cells and T-suppressor cells with an activated phenotype (HLA-DR(+)) was increased in patients with T-LGL, T-LGL/MDS and MDS, but the increase in activated T-suppressor cells in patients with T-LGL/MDS was not statistically significant. Autoreactive T cells may suppress haematopoiesis and contribute to the cytopenia in T-LGL and some patients with MDS, leading to T-LGL/MDS. The lower response rate of MDS or T-LGL/MDS to immunosuppression, compared with T-LGL alone, may reflect the older age and intrinsic stem cell abnormalities in MDS and T-LGL/MDS patients.

Parvovirus B19: implications for transfusion medicine. Summary of a workshop

This 1-day workshop showed that the infectivity of B19 DNA in donor blood and the neutralizing action of different antibodies present in the donated blood are not yet fully understood. It is possible that B19-induced anemia and reticulocytopenia are not being recognized in transfused recipients other than those in specific risk groups. The testing of blood components for any infectious agent is usually clinically driven, and, if B19 NAT were recommended at the present time in other than plasma products, a CMV-like model might prove appropriate; that is, virus screening would be performed on blood components destined for high-risk groups only. Currently, there is insufficient evidence to recommend universal testing, especially for single units. Workshop participants recommended that basic research continue in the scientific areas addressed. If clinical trials were to be developed, participants recommended that they include special risk groups such as seronegative pregnant women and children with malignancies who are receiving chemotherapy.

High-dose cyclophosphamide in severe aplastic anaemia: a randomised trial

BACKGROUND

High-dose cyclophosphamide has been proposed as an alternative immunosuppressive agent for treatment of severe aplastic anaemia, with a response rate similar to that with regimens containing antithymocyte globulin (ATG) but neither relapse nor clonal haematological complications. We undertook a phase III, prospective, randomised trial to compare response rates to immunosuppression with either high-dose cyclophosphamide plus cyclosporin or conventional immunosuppression with ATG plus cyclosporin in previously untreated patients.

METHODS

Between June, 1997, and March, 2000, 31 patients were enrolled. 15 were assigned cyclophosphamide (1 h intravenous infusion of 50 mg/kg daily for 4 days) and 16 were assigned ATG (40 mg/kg daily for 4 days); both groups received cyclosporin, initially at 12 mg/kg daily with adjustment to maintain concentrations at 200-400 microg/L, for 6 months. The primary endpoint was haematological response (no longer meeting criteria for severe aplastic anaemia). The trial was terminated prematurely after three early deaths in the cyclophosphamide group. Analyses were by intention to treat.

FINDINGS

Median follow-up was 21.9 months (range 1-33). There was excess morbidity in the cyclophosphamide group (invasive fungal infections, four cyclophosphamide vs no ATG patients; p=0.043) as well as excess early mortality (three deaths within the first 3 months cyclophosphamide vs no ATG patients; p=0.101). There was no significant difference at 6 months after treatment in the overall response rates among evaluable patients (six of 13 [46%] cyclophosphamide vs nine of 12 [75%] ATG).

INTERPRETATION

A longer period of observation will be necessary to assess the secondary endpoints of relapse and late clonal complications as well as disease-free and overall survival. However, cyclophosphamide seems a dangerous choice for treatment of this disorder, given the good results achievable with standard therapy.

Sustained long-term hematologic recovery despite a marked quantitative defect in the stem cell compartment of patients with aplastic anemia after immunosuppressive therapy

Previously, we reported that patients with aplastic anemia (AA) have profoundly decreased numbers of hematopoietic progenitor and stem cells as measured in the long-term culture initiating cell (LTC-IC) assay (Blood 1996;88:1983-1991). We now present results of a long-term prospective study of LTC-IC numbers in peripheral blood (PB) and bone marrow (BM) of patients treated with antithymocyte globulin and cyclosporin A. Numbers of secondary colony forming cells (secondary CFC) in long-term bone marrow culture (LTBMC) were used to quantitate LTC-IC. BM (N = 35) and PB (N = 41) secondary CFC from both untreated severe AA patients and responders to immunosuppressive therapy who were sampled up to 6 years after initial treatment were compared. Normal controls showed 148 +/- 38 (N = 17) and 16 +/- 3 (N= 14) secondary CFC per 10(6) in BM and PB, respectively. In cross-sectional analysis, prior to therapy, AA patients showed 2.6 +/- 1 (mean +/- SD) secondary CFC/10(6) BM MNC; within the first year after initial treatment (N = 14), secondary CFC number rose modestly to 8.2 +/- 2.2/10(6) MNC, and further increased to 15.8 +/- 7 (N = 17) at 2 years and 16.2 +/- 7/10(6) MNC (N = 25) 3 years after treatment. There was no further improvement in the secondary CFC numbers at 4, 5, and > or =6 years (N = 37). Thus, while BM secondary CFC increased about 6-fold at 3 years post-therapy compared to presentation, they remained about only 10% of normal despite hematologic recovery. Similar data were obtained for PB, with approximately 4-fold increase in secondary CFC numbers within 2 years of therapy, to about 15% of normal values. We confirmed these observations in patients studied serially over a period of 4 years: initial secondary CFC were 2.35 +/- 1/10(6) BM MNC and 0.11 +/- 0.1/10(6) PB MNC improving to an average of 6 +/- 1. 2 (BM; N = 12) and 2.4 +/- 1/10(6) MNC (PB; N = 14). In many cases of partial recovery, PB counts improve but do not normalize. When we studied secondary CFC numbers only in patients who achieved complete normalization of PB counts (ANC >1,500/mm(3); platelets >10(5)/mm(3) and absolute reticulocytes >5 x 10(4)/mm(3)), BM secondary CFC were significantly higher than in patients with partial recovery; the PB secondary CFC number was modestly increased but remained below the normal values. Within the group of patients with complete recovery, there was no correlation between the secondary CFC and time after initial treatment. In addition, there also was no correlation between the secondary CFC number at presentation and the quality of hematopoietic recovery. Despite a limited expansion potential of a severely reduced stem cell pool, their numbers are sufficient to provide a long-term supply of mature blood cells. Am. J. Hematol. 65:123-131, 2000. Published 2000 Wiley-Liss, Inc.

Sustained long-term hematologic recovery despite a marked quantitative defect in the stem cell compartment of patients with aplastic anemia after immunosuppressive therapy

Previously, we reported that patients with aplastic anemia (AA) have profoundly decreased numbers of hematopoietic progenitor and stem cells as measured in the long-term culture initiating cell (LTC-IC) assay (Blood 1996;88:1983-1991). We now present results of a long-term prospective study of LTC-IC numbers in peripheral blood (PB) and bone marrow (BM) of patients treated with antithymocyte globulin and cyclosporin A. Numbers of secondary colony forming cells (secondary CFC) in long-term bone marrow culture (LTBMC) were used to quantitate LTC-IC. BM (N = 35) and PB (N = 41) secondary CFC from both untreated severe AA patients and responders to immunosuppressive therapy who were sampled up to 6 years after initial treatment were compared. Normal controls showed 148 +/- 38 (N = 17) and 16 +/- 3 (N= 14) secondary CFC per 10(6) in BM and PB, respectively. In cross-sectional analysis, prior to therapy, AA patients showed 2.6 +/- 1 (mean +/- SD) secondary CFC/10(6) BM MNC; within the first year after initial treatment (N = 14), secondary CFC number rose modestly to 8.2 +/- 2.2/10(6) MNC, and further increased to 15.8 +/- 7 (N = 17) at 2 years and 16.2 +/- 7/10(6) MNC (N = 25) 3 years after treatment. There was no further improvement in the secondary CFC numbers at 4, 5, and > or =6 years (N = 37). Thus, while BM secondary CFC increased about 6-fold at 3 years post-therapy compared to presentation, they remained about only 10% of normal despite hematologic recovery. Similar data were obtained for PB, with approximately 4-fold increase in secondary CFC numbers within 2 years of therapy, to about 15% of normal values. We confirmed these observations in patients studied serially over a period of 4 years: initial secondary CFC were 2.35 +/- 1/10(6) BM MNC and 0.11 +/- 0.1/10(6) PB MNC improving to an average of 6 +/- 1. 2 (BM; N = 12) and 2.4 +/- 1/10(6) MNC (PB; N = 14). In many cases of partial recovery, PB counts improve but do not normalize. When we studied secondary CFC numbers only in patients who achieved complete normalization of PB counts (ANC >1,500/mm(3); platelets >10(5)/mm(3) and absolute reticulocytes >5 x 10(4)/mm(3)), BM secondary CFC were significantly higher than in patients with partial recovery; the PB secondary CFC number was modestly increased but remained below the normal values. Within the group of patients with complete recovery, there was no correlation between the secondary CFC and time after initial treatment. In addition, there also was no correlation between the secondary CFC number at presentation and the quality of hematopoietic recovery. Despite a limited expansion potential of a severely reduced stem cell pool, their numbers are sufficient to provide a long-term supply of mature blood cells. Am. J. Hematol. 65:123-131, 2000. Published 2000 Wiley-Liss, Inc.

Regression of metastatic renal-cell carcinoma after nonmyeloablative allogeneic peripheral-blood stem-cell transplantation

BACKGROUND

Since allogeneic stem-cell transplantation can induce curative graft-versus-leukemia reactions in patients with hematologic cancers, we sought to induce analogous graft-versus-tumor effects in patients with metastatic renal-cell carcinoma by means of nonmyeloablative allogeneic peripheral-blood stem-cell transplantation.

METHODS

Nineteen consecutive patients with refractory metastatic renal-cell carcinoma who had suitable donors received a preparative regimen of cyclophosphamide and fludarabine, followed by an infusion of a peripheral-blood stem-cell allograft from an HLA-identical sibling or a sibling with a mismatch of a single HLA antigen. Cyclosporine, used to prevent graft-versus-host disease, was withdrawn early in patients with mixed T-cell chimerism or disease progression. Patients with no response received up to three infusions of donor lymphocytes.

RESULTS

At the time of the last follow-up, 9 of the 19 patients were alive 287 to 831 days after transplantation (median follow-up, 402 days). Two had died of transplantation-related causes, and eight from progressive disease. In 10 patients (53 percent) metastatic disease regressed; 3 had a complete response, and 7 had a partial response. The patients who had a complete response remained in remission 27, 25, and 16 months after transplantation. Regression of metastases was delayed, occurring a median of 129 days after transplantation, and often followed the withdrawal of cyclosporine and the establishment of complete donor-T-cell chimerism. These results are consistent with a graft-versus-tumor effect.

CONCLUSIONS

Nonmyeloablative allogeneic stem-cell transplantation can induce sustained regression of metastatic renal-cell carcinoma in patients who have had no response to conventional immunotherapy.

Sequencing and characterization of A-2 plaque virus: A new member of the Picornaviridae family

A-2 plaque virus (A2 virus) was originally isolated from the icteric-phase sera of US servicemen with viral hepatitis in the 1960s, but apart from a preliminary characterization little is known about the agent. We have now successfully cloned and sequenced the complete viral genome. A2 viral RNA consists of 7312 nucleotides, excluding the 62 nucleotide poly(A) tract at the 3' end, with one large open reading frame. Although clearly a member of the Picornaviridae, there is low homology to the available sequences, suggesting it is only loosely related to the classic rhino/enterovirus genus. In addition, there was no reactivity with group specific monoclonal antibody blends against polioviruses, enteroviruses 70 and 71, coxsackievirus B, and echoviruses. Two tamarins were inoculated with A2 virus to study viral pathogenesis. Both animals that received A2 virus became transiently viremic 1 week after the infection, as determined by RT-PCR, and they developed an antibody response to A2 virus. However, no physical signs or biochemical abnormalities, including elevated liver transaminases, were observed. In addition, no liver samples from patients with fulminant hepatitis (n = 7) or controls (n = 7) were positive for A2 viral RNA nor was anti-A2 neutralizing antibody detected in sera from hepatitis patients (n = 14), healthy laboratory donors (n = 14), or US blood donors (n = 33); however, most sera contained antibodies reactive with A2 virus proteins. These results suggest that A2 virus is a new member of the Picornaviridae but that its pathogenicity in nonhuman primates and association with human disease still need to be determined.

Pharmacologic doses of granulocyte colony-stimulating factor affect cytokine production by lymphocytes in vitro and in vivo

Peripheral blood stem cell (PBSC) transplantation is successful in improving engraftment without increasing acute graft-versus-host disease (GVHD), despite much larger numbers of T cells in unmanipulated PBSCs than in bone marrow grafts. In mouse models and retrospective human studies, granulocyte colony-stimulating factor (G-CSF) therapy has been associated with less acute GVHD. We studied the effect of G-CSF on interferon (IFN)-gamma and IL-4 expression in CD4(+) lymphocytes. CD4(+) cells co-cultivated with G-CSF and stimulated with PHA or CD3 monoclonal antibodies showed significant decreases in IFN-gamma and increases in IL-4 expression (n = 13; P <. 01). G-CSF appeared to have a direct effect on CD4(+) cells independent of monocytes present in the culture because purified CD4(+) cells exposed to G-CSF, washed, and cocultivated with untreated monocytes demonstrated similar changes in IFN-gamma and IL-4 expression, whereas untreated CD4(+) cells cocultured with G-CSF-stimulated monocytes behaved as controls. We then studied peripheral blood mononuclear cells (PBMCs) from G-CSF-mobilized PBSC donors. When their PBMCs were cultured with PHA or CD3 monoclonal antibody, the percent of IFN-gamma-expressing cells decreased by a mean of 55% and 42%, respectively, whereas the percent of IL-4-containing cells increased by a mean of 39% and 58%, respectively, following G-CSF stimulation. Increased apoptosis of IFN-gamma-producing CD4(+) cells was not responsible for the shift in TH1/TH2 subsets. G-CSF-R mRNA was present in both CD4(+) and CD8(+) cells. These results suggest that G-CSF decreases IFN-gamma and increases IL-4 production in vitro and in vivo and likely modulates a balance between TH1 and TH2 cells, an effect that may be important in PBSC transplantation.

GB virus C/Hepatitis G virus infection is frequent in American children and young adults

The novel flavivirus GB virus C/hepatitis G virus (GBV-C/HGV) has been detected in approximately 2% of blood donors in the United States, and neutralizing antibody to the envelope protein (E2), a marker of previous infection with GBV-C/HGV, is present in approximately 9% of donors. The rate of GBV-C/HGV infection among American children is unknown. To determine whether viral infection might occur during childhood, 160 serum specimens (obtained from blood bank samples) from children and young adults with no history of transfusion were tested. Viral RNA and antibody to E2 were detected in 6.3% and 9.4% of subjects, respectively. Evidence of previous or current infection (viremia and/or antibody to E2) was detected in 13.8% of subjects, indicating that GBV-C/HGV infection appears to be common among American children and young adults, even in the absence of blood transfusion.

Prevalence of the newly described human circovirus, TTV, in United States blood donors

BACKGROUND

A novel nonenveloped single-stranded circular DNA virus (TTV) was recently identified. The prevalence of TTV in blood donors in the United States is, however, still unclear.

STUDY DESIGN AND METHODS

Viral DNA was detected in US blood donors from five cities by using two sets of TTV primers: NG059/NG061/NG063 primers, which amplified the conserved region of strains 1 and 2, and T801/T935 primers, which amplified the 5' end region of the TTV sequence. A TTV antibody assay system was based on the detection of the truncated open reading frame (ORF)-1 (amino acids 1-411) from type 1b. The truncated ORF-1 was expressed as a fusion protein in Escherichia coli, and the fusion protein was used as the antigen in the antibody assay system.

RESULTS

Viremia was detected in 21 (8. 4%) of 250 donors by use of NG059/NG061/NG063 primers and 104 (41. 6%) of 250 by use of T801/T935 primers. There was little correlation among the assays, which suggests the preferential detection of different strains with the different primers. TTV antibody was detected in 38 of 100 donors: 32 (84%) of 38 with concurrent TTV viremia and 6 (16%) of 38 without TTV viremia. TTV viremia and/or TTV antibody-positive samples were detected in 52 (52%) of 100 of US blood donors.

CONCLUSION

Evidence of infection or exposure to TTV appears to be common among blood donors in United States.

CD34+ cell dose predicts relapse and survival after T-cell-depleted HLA-identical haematopoietic stem cell transplantation (HSCT) for haematological malignancies

Seventy-eight patients with haematological malignancies, received T-cell-depleted stem cell transplants and cyclosporin followed by delayed add-back of donor lymphocytes to prevent leukaemia relapse. The source of stem cells was bone marrow in 50 patients and granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood in 28 patients. In univariate analysis, only the CD34+ cell dose (but not the stem cell source or the T lymphocyte dose) and disease status were predictive for transplant-related mortality, relapse and survival. Patients receiving >/= 3 x 106 CD34+ cells/kg had an overall actuarial survival of 68% compared with 52%, 35% and 10%, respectively, for cell doses of 2-2.99, 1-1.99 and < 1 x 106/kg. Multivariate analysis of risk factors for relapse identified disease risk and CD34+ cell dose as the only factors. Relapse was 62.5% in 38 patients at high risk of relapse vs. 25% for 40 patients at intermediate or low risk. CD34+ cell doses of >/= 3 x 106/kg were associated with a 13.5% relapse vs. 48% for recipients of lower doses. This favourable effect of CD34+ cell dose on relapse was apparent in both high- and intermediate- plus low-risk groups. Our results support the potential benefit of a high stem cell dose in lowering transplant-related mortality (TRM) and in reducing relapse after allogeneic marrow or blood stem cell transplants.

Clinical and laboratory evidence for a trilineage haematopoietic defect in patients with refractory Diamond-Blackfan anaemia

Diamond-Blackfan anaemia (DBA) is a constitutional pure red cell aplasia presenting in early childhood. In some patients, neutropenia and/or thrombocytopenia have also been observed during the course of the disease. We have followed 28 patients with steroid-refractory DBA for up to 13 years with serial peripheral blood counts and bone marrow (BM) aspirates and biopsies. In 21/28 (75%) patients, moderate to severe generalized BM hypoplasia developed, with overall cellularities ranging from 0% to 30%. Marrow hypoplasia correlated with the development of neutropenia (9/21; 43%) and/or thrombocytopenia (6/21; 29%) in many patients. No patient had either cytogenetic abnormalities or progressed to acute leukaemia, although one 13-year-old developed marked marrow fibrosis and trilineage dysplasia. We used the in vitro long-term culture-initiating cell (LTC-IC) assay to quantify multilineage, primitive haematopoietic progenitors in a representative subset of these patients. LTC-IC assays showed equivalent frequencies of cobblestone area-forming cells (CAFCs) with a mean of 5.42/10(5) cells +/- 1.9 SD and 6.13/10(5) cells +/- 2.6 SD in nine patients and six normal controls respectively. The average clonogenic cell output per LTC-IC, however, was significantly lower in DBA patients (mean 2.16 +/- 1.2 SD vs. 7. 36 +/- 2.7 SD in normal controls, P = 0.0008). Our results suggest that the underlying defect in patients with severe refractory DBA may not be limited to the erythroid lineage, as was evidenced by the development of pancytopenia, bone marrow hypoplasia and reduced clonogenic cell output in LTC-IC assays.

Engraftment kinetics after nonmyeloablative allogeneic peripheral blood stem cell transplantation: full donor T-cell chimerism precedes alloimmune responses

Nonmyeloablative allogeneic stem cell transplantation has recently been explored as a safer alternative to conventional high-dose transplant regimens. Although a high incidence of mixed chimerism after nonmyeloablative procedures has been reported, the exact kinetics of engrafting donor cells in specific cellular lineages has yet to be defined. We investigated lineage-specific chimerism in 15 patients receiving an allogeneic peripheral blood stem cell (PBSC) transplant from an HLA-identical (n = 14) or a 5/6 antigen-matched sibling donor after a preparative regimen of cyclophosphamide and fludarabine. Donor chimerism was assessed weekly in T lymphocytes and myeloid cells by polymerase chain reaction (PCR) of minisatellite regions. Eight patients survived between 121 to 409 days after transplant. Ten of 14 patients surviving more than 30 days (71.4%) had delayed disease regression consistent with a graft-versus-malignancy (GVM) effect. One patient rejected the transplant with subsequent recovery of autologous hematopoiesis. Hematological recovery was rapid (median, 11 days to >/=500 neutrophils/microL) and was initially predominantly recipient in origin. Donor myeloid chimerism gradually supplanted recipient hematopoiesis and became fully donor in all survivors by 200 days after transplantation. In contrast, T-cell engraftment was more rapid, with full chimerism in 7 patients by day 30 and in 6 further patients by day 200 after cyclosporine withdrawal and donor lymphocyte infusion. Full donor T-cell engraftment preceded donor myeloid engraftment, acute graft-versus-host disease, and disease regression, consistent with a requirement for 100% donor T-cell chimerism for full expression of the alloresponse. These results emphasize the importance of lineage-specific chimerism analysis to successfully manipulate engraftment after nonmyeloablative allogeneic PBSC transplantation.

Paroxysmal nocturnal hemoglobinuria cells in patients with bone marrow failure syndromes

BACKGROUND

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem-cell disorder in which the affected cells are deficient in glycosylphosphatidylinositol (GPI)-anchored proteins. Paroxysmal nocturnal hemoglobinuria is frequently associated with aplastic anemia, although the basis of this relation is unknown.

OBJECTIVE

To assess the PNH status of patients with diverse marrow failure syndromes.

DESIGN

Correlation of cytofluorometric data with clinical features.

SETTING

Hematology Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland.

PATIENTS

115 patients with aplastic anemia, 39 patients with myelodysplasia, 28 patients who had recently undergone bone marrow transplantation, 18 patients with cancer that was treated with chemotherapy, 13 patients with large granular lymphocytosis, 20 controls who had received renal allografts, and 21 healthy participants.

INTERVENTION

Patients with aplastic anemia, myelodysplasia, or renal allografts received antithymocyte globulin.

MEASUREMENTS

Flow cytometry was used to assess expression of GPI-anchored proteins on granulocytes.

RESULTS

Evidence of PNH was found in 25 of 115 (22%) patients with aplastic anemia. No patient with normal GPI-anchored protein expression at presentation developed PNH after therapy (n = 16). Nine of 39 (23%) patients with myelodysplasia had GPI-anchored protein-deficient cells. Abnormal cells were not detected in patients with constitutional or other forms of bone marrow failure or in renal allograft recipients who had received antithymocyte globulin. Aplastic anemia is known to respond to immunosuppressive therapy; in myelodysplasia, the presence of a PNH population was strongly correlated with hematologic improvement after administration of antithymocyte globulin (P = 0.0015).

CONCLUSIONS

Flow cytometric analysis is superior to the Ham test and permits concomitant diagnosis of PNH in about 20% of patients with myelodysplasia (a rate similar to that seen in patients with aplastic anemia). The presence of GPI-anchored protein-deficient cells in myelodysplasia predicts responsiveness to immunosuppressive therapy. Early emergence of GPI-anchored protein-deficient hematopoiesis in a patient with marrow failure may point to an underlying immune pathogenesis.

Engraftment of hematopoietic progenitor cells transduced with the Fanconi anemia group C gene (FANCC)

Fanconi anemia (FA) is an autosomal recessive disorder that leads to aplastic anemia. Mutations in the FANCC gene account for 10-15% of cases. FA cells are abnormally sensitive to DNA-damaging agents such as mitomycin C (MMC). Transfection of normal FANCC into mutant cells corrects this hypersensitivity and improves their viability in vitro. Four FA patients, representing the three major FANCC mutation subgroups, were entered into a clinical trial of gene transduction aimed at correction of the hematopoietic defect. Three patients received three or four cycles of gene transfer, each consisting of one or two infusions of autologous hematopoietic progenitor cells that had been transduced ex vivo with a retroviral vector carrying the normal FANCC gene. Prior to infusion, the FANCC transgene was demonstrated in transduced CD34-enriched progenitor cells. After infusion, FANCC was also present transiently in peripheral blood (PB) and bone marrow (BM) cells. Function of the normal FANCC transgene was suggested by a marked increase in hematopoietic colonies measured by in vitro cultures, including colonies grown in the presence of MMC, after successive gene therapy cycles in all patients. Transient improvement in BM cellularity coincided with this expansion of hematopoietic progenitors. A fourth patient, who received a single infusion of transduced CD34-enriched BM cells, was given radiation therapy for a concurrent gynecologic malignancy. The FANCC transgene was detected in her PB and BM cells only after recovery from radiation-induced aplasia, suggesting that FANCC gene transduction confers a selective engraftment advantage. These experiments highlight both the potential and difficulties in applying gene therapy to FA.

Human immunodeficiency virus type 1 protease inhibitor modulates activation of peripheral blood CD4(+) T cells and decreases their susceptibility to apoptosis in vitro and in vivo

CD4(+) T cells from patients with human immunodeficiency virus (HIV) infection undergo apoptosis at an increased rate, which leads to their depletion during disease progression. Both the Fas-Receptor (Fas-R) and interleukin-1beta (IL-1beta)-converting enzyme (ICE; caspase 1) appear to play a role in the mechanism of apoptosis of CD4(+) lymphocytes. Although Fas-R is upregulated on both CD4(+) and CD8(+) cells in HIV-infected patients, results from our laboratory and others indicate that, in patients with advanced disease, CD4(+) cells preferentially express ICE. Protease inhibitors have successfully halted the progression of HIV disease and increased CD4(+) T counts. In this study, we examined the effect of protease inhibitors on Fas-R (CD95), ICE (caspase 1) expression, apoptosis, and cell death in CD4(+) T cells of (1) HIV-infected patients who were receiving protease inhibitors, and (2) normal and patient CD4(+) T cells cultured with a protease inhibitor in vitro. Fifteen patients with advanced HIV disease on treatment showed dramatically decreased CD4(+) T-cell ICE expression, diminished apoptosis, and increased numbers of CD4(+) cells within 6 weeks of institution of protease inhibitor therapy, and before down-modulation of Fas-R (CD95) expression was evident. To determine the role of HIV infection, we studied the effect of ritonavir, a protease inhibitor, on normal and patient cells in vitro. Stimulated and unstimulated normal CD4(+) T cells, cultured with protease inhibitor, demonstrated markedly decreased apoptosis and ICE expression (P =. 01). While Fas-R expression was not significantly altered during short-term culture by such treatment, Fas-Ligand (Fas-L) membrane expression of phytohemagglutinin (PHA)-stimulated blood lymphocytes was decreased by protease inhibitor. In the presence of ritonavir, CD4(+) T cells from HIV-infected patients showed similar changes in ICE intracellular levels without alteration of Fas expression. In conclusion, protease inhibitors appear to decrease CD4(+) T-cell ICE expression and apoptosis before they affect Fas-R expression in HIV-infected patients. This action was independent of HIV infection, as similar effects were seen in CD4(+) T cells from normal controls. Some of the benefit of protease inhibitors may be related to modification of programmed cell death, which increases CD4(+) T-cell number. Whether this is due to directly to the changes effected in the caspase system remains to be determined.

Regional patterns in the incidence of aplastic anemia in Thailand. The Aplastic Anemia Study Group

The annual incidence of aplastic anemia has been determined in a rigorous and standardized epidemiologic study conducted in Thailand. A total of 374 cases were identified over a period of 3-6 years in three geographically defined and distinct regions of the country; Bangkok, Khonkaen in the northeast, and Songkla in the south. The incidence was 3.9 cases per million persons in Bangkok, 3.0 per million in Songkla, and 5.0 per million in Khonkaen. These rates are as high or higher than in any region of Europe or Israel as reported in the International Agranulocytosis and Aplastic Anemia Study, in which the methods and case definition were the same. Rates were stable over the course of the study. There were marked differences in incidence between northern and southern rural regions of Thailand, and among Bangkok suburbs. These differences, together with an unusual peak in the incidence among young people in Bangkok, suggest the possibility of occupational and environmental factors in the etiology of aplastic anemia.

Expression of interferon-gamma by stromal cells inhibits murine long-term repopulating hematopoietic stem cell activity

Several lines of evidence suggest that overexpression of interferon gamma (IFN-gamma) in the marrow microenvironment may play a role in the pathogenesis of marrow suppression in aplastic anemia. We previously showed that overexpression of IFN-gamma by marrow stromal cells inhibits human long-term culture initiating cell activity assayed in vitro to a much greater degree than the addition of soluble IFN-gamma. The effect of IFN-gamma on true repopulating stem cells assayed in vivo has not been studied previously. We compared the effect of co-culture of murine marrow cells in the presence of stromal cells transduced with a retroviral vector expressing murine IFN-gamma vs stromal cells transduced with a control neo vector. Using a murine congenic competitive repopulation assay, there was significantly less long-term repopulating stem cell activity remaining after culture on mIFN-gamma-expressing stroma as compared to control stroma. We also investigated the effect of directly transducing murine bone marrow cells with the mIFN-gamma or control vector. Marrow cells transduced with either vector were transplanted into W/Wv recipient mice. The percentage of vector-containing cells in the mIFN-gamma mice was significantly lower than in the control mice, suggesting that mIFN-gamma-transduced primitive cells may not have survived culture, or that mIFN-gamma directly decreases gene transfer into repopulating cells. Despite no significant differences in white or red blood cells in the mice transplanted with the mIFN-gamma-transduced cells, the number of bone marrow colony-forming unit-C 16 weeks after transplantation was significantly lower in the IFN-gamma group. These data indicate that ectopic or overexpression of mIFN-gamma, especially by marrow microenvironmental elements, may have a marked effect on primitive hematopoiesis as assayed in vivo.

Agranulocytosis in Bangkok, Thailand: a predominantly drug-induced disease with an unusually low incidence. Aplastic Anemia Study Group

Agranulocytosis, a syndrome characterized by a marked reduction in circulating granulocytes, is strongly associated with medical drug use in Europe and the United States. Unregulated use of common pharmaceutical agents in developing countries has been suspected of causing large numbers of cases of agranulocytosis and deaths, especially among children. To elucidate the incidence and etiology of agranulocytosis in Thailand, a population-based case-control study of symptomatic agranulocytosis that resulted in hospital admission was conducted in Bangkok from 1990 to 1994. An attempt was also made to study the disease in Khonkaen (in northeastern Thailand) and Songkla (in southern Thailand), but there were insufficient cases in the latter regions, and the analysis was confined to subjects from Bangkok. In that region, the overall incidence of agranulocytosis was 0.8 per million per year; there were no deaths. As expected, the incidence was higher in females (0.9 per million), and it increased with age (4.3 per million beyond age 60). Among 25 cases and 529 controls the relative risk estimate for a combined category of all suspect drugs was 9.2 (95% confidence interval = 3.9-21), and the proportion of cases that could be attributed to drug use was 68%. For individual drugs and drug classes the data were sparse; within these limitations, the strongest association appeared to be with antithyroid drugs. One case and three controls were exposed to dipyrone, a drug known to cause agranulocytosis; with such scanty data the risk could not be evaluated. Exposure to pesticides or solvents was not associated with an increased risk. This is the first formal epidemiologic study of agranulocytosis in a developing country. As in the West, most cases are attributable to medical drug use. However, the incidence of agranulocytosis in Bangkok, and apparently, in Thailand as a whole, is unusually low, and the disease does not pose a public health risk.

Generation of neutralizing human monoclonal antibodies against parvovirus B19 proteins

Infections caused by human parvovirus B19 are known to be controlled mainly by neutralizing antibodies. To analyze the immune reaction against parvovirus B19 proteins, four cell lines secreting human immunoglobulin G monoclonal antibodies (MAbs) were generated from two healthy donors and one human immunodeficiency virus type 1-seropositive individual with high serum titers against parvovirus. One MAb is specific for nonstructural protein NS1 (MAb 1424), two MAbs are specific for the unique region of minor capsid protein VP1 (MAbs 1418-1 and 1418-16), and one MAb is directed to major capsid protein VP2 (MAb 860-55D). Two MAbs, 1418-1 and 1418-16, which were generated from the same individual have identity in the cDNA sequences encoding the variable domains, with the exception of four base pairs resulting in only one amino acid change in the light chain. The NS1- and VP1-specific MAbs interact with linear epitopes, whereas the recognized epitope in VP2 is conformational. The MAbs specific for the structural proteins display strong virus-neutralizing activity. The VP1- and VP2-specific MAbs have the capacity to neutralize 50% of infectious parvovirus B19 in vitro at 0.08 and 0.73 microgram/ml, respectively, demonstrating the importance of such antibodies in the clearance of B19 viremia. The NS1-specific MAb mediated weak neutralizing activity and required 47.7 micrograms/ml for 50% neutralization. The human MAbs with potent neutralizing activity could be used for immunotherapy of chronically B19 virus-infected individuals and acutely infected pregnant women. Furthermore, the knowledge gained regarding epitopes which induce strongly neutralizing antibodies may be important for vaccine development.