Lymphocyte phenotype and lymphokines following anti-thymocyte globulin therapy in patients with aplastic anaemia

Activity of alemtuzumab monotherapy in treatment-naive, relapsed, and refractory severe acquired aplastic anemia

Antithymocyte globulin (ATG) + cyclosporine is effective in restoring hematopoiesis in severe aplastic anemia (SAA). We hypothesized that the humanized anti-CD52 mAb alemtuzumab might be active in SAA because of its lymphocytotoxic properties. We investigated alemtuzumab monotherapy from 2003-2010 in treatment-naive, relapsed, and refractory SAA in 3 separate research protocols at the National Institutes of Health. Primary outcome was hematologic response at 6 months. For refractory disease, patients were randomized between rabbit ATG + cyclosporine (n = 27) and alemtuzumab (n = 27); the response rate for alemtuzumab was 37% (95% confidence interval [CI], 18%-57%) and for rabbit ATG 33% (95% CI, 14%-52%; P = .78). The 3-year survival was 83% (95% CI, 68%-99%) for alemtuzumab and 60% (95% CI, 43%-85%) for rabbit ATG (P = .16). For relapsed disease (n = 25), alemtuzumab was administered in a single-arm study; the response rate was 56% (95% CI, 35%-77%) and the 3-year survival was 86% (95% CI, 72%-100%). In treatment-naive patients (n = 16), alemtuzumab was compared with horse and rabbit ATG in a 3-arm randomized study; the response rate was 19% (95% CI 0%-40%), and the alemtuzumab arm was discontinued early. We conclude that alemtuzumab is effective in SAA, but best results are obtained in the relapsed and refractory settings. The present trials were registered at www.clinicaltrials.gov as NCT00195624, NCT00260689, and NCT00065260.

Abnormal immunity and stem/progenitor cells in acquired aplastic anemia

Acquired aplastic anemia (AA) is considered as an immune-mediated bone marrow failure syndrome, characterized by hypoplasia and pancytopenia with fatty bone marrow. Abnormal immunity is the major factor mediating the pathogenesis of acquired AA. Activated DCs might promote the polarization to Th1 cells, and activate CD8(+) T cells. A variety of immune molecules including IFN-gamma, TNF-alpha, MIP-1alpha and IL-2, 8, 12, 15, 17, 23, produced by them and stromal cells, compose a cytokine network to destruct stem/progenitor cells as well as hematopoietic stem/progenitor cells, mesenchymal stem cells (MSCs) and angioblasts/endothelial progenitor cells. Inversely, deficient MSCs, CD4(+)CD25(+) T cells, NK cells, NKT cells and early hematopoietic growth factors diminish the capacity of immune regulation and the support of hematopoiesis. As a result, stem/progenitor cells are significantly impaired to be disabled cells with markedly deficient proliferation, differentiation, induced apoptosis and dysfunctional response to growth factor stimuli, together with rare normal ones. Although some patients can be ameliorated by stem-cell transplantation or immunosuppressive therapy, more effective and convenient therapies such as patient-specific pluripotent iPS cells based on definite pathogenesis are expected.

Apoptosis and complement-mediated lysis of myeloma cells by polyclonal rabbit antithymocyte globulin

Current monoclonal antibody therapies for multiple myeloma have had limited success, perhaps due to narrow target specificity. We have previously described the ability of polyclonal rabbit antithymocyte globulin (rATG) to induce caspase- and cathepsin-mediated apoptosis in human B and plasma cells. We now extend this observation to myeloma cells. Complement independent cell death was measured after addition of rATG (1-1000 microg/mL) to cultures of myeloma cell lines or primary CD138+ isolates from patient bone marrow aspirates. rATG induced significant levels of apoptosis in myeloma cells as assayed by caspase induction, annexin V binding, subdiploid DNA fragmentation, plasma-membrane permeability, and loss of mitochondrial-membrane potential. Addition of complement greatly augmented myeloma-cell death. Binding of rATG to individual myeloma cell-surface proteins, primarily CD38, CD52, CD126, and CD138, was demonstrated by competitive inhibition experiments with targeted monoclonal antibodies. Three pathways of cell death were identified involving caspase activation, cathepsin D, and the genistein sensitive tyrosine kinase pathway. Fab'2 fragments of rATG had reduced proapoptotic activity, which was restored by coincubation with Fc fragments, and anti-CD32 or anti-CD64 antibodies. We conclude that rATG is an effective agent for in vitro induction of apoptosis in multiple myeloma, and that exploratory clinical trials may be warranted.

Bone Marrow Transplantation in Thalassemia Major Patients Using “Short” Anti-Thymocyte Globulin Therapy in Shiraz, Southern Iran

Allogeneic bone marrow transplantation (BMT) was performed on 113 Iranian transfusion-dependent thalassemia major patients from May 1993 through September 2003. To have at least 2 years follow-up, we report BMT on 90 patients transplanted up to December 2001. The donors were human leukocyte antigen (HLA)-identical, mixed lymphocyte culture (MLC)-nonreactive siblings (n = 74) on parents (n = 6); HLA-identical MLC-reactive siblings (n = 5) or parents (n = 1); and one HLA antigen-mismatched sibling (n = 4). The induction regimen in 11 patients was oral busulfan (BU) (14 mg/kg) and IV cyclophosphamide (CY; 200 mg/kg); in fifteen patients it was BU (15 mg/kg) and cyclophosphamide (CY; 200 mg/kg); in 47 patients, BU (15 mg/kg), CY (200 mg/kg), and short course of anti-thymocyte globulin (ATG, horse; 40 mg/kg including 10 mg/kg on days -2, -1, +1, +2); and in 15 patients, BU (15 mg/kg) CY (200 mg/kg), and ATG (60 to 100 mg/kg; 10 mg/kg at 3 to 5 days before and after BMT). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and prednisolone. The group who received BU (14 mg/kg) and CY (200 mg/kg), as compared to the group receiving BU (15 mg/kg) and CY (200 mg/kg), was of younger age and lower risk; median age 7 versus 10 years, and 46% versus 7% in Lucarelli's risk group class I (the best prognostic group), respectively. These patients showed a lower disease-free survival (DFS), namely 64% versus 73%, with a follow up of 2 to 10.5 years. Thus from 9.5 years ago, our standard protocol for BU has been 15 mg/kg. The group who received "short" ATG (40 mg/kg), BU (15 mg/kg), and CY (200 mg/kg) showed almost the same outcome as the group who received a higher dose of ATG (60 to 100 mg/kg), namely DFS 72% versus 73%, respectively, despite the fact that half of both groups were included in the Lucarelli's risk group class III (the worst prognostic group) 49% versus 53%. We showed the same DFS for the patients who received BU (15 mg/kg), CY (200 mg/kg), and no ATG compared with the ATG group (73% vs 72%), but 27% of the group without ATG developed grade IV acute GVHD and 54% developed chronic GVHD. In the group with short ATG, 15% and 17% of patients developed grade IV acute and chronic GVHD, respectively. There was no significant difference for falls in platelets and white blood cell or engraftment days and the number of packed red blood cell transfusions among the groups. The median hospital stay was longer for the group with BU (15 mg/kg), CY (200 mg/kg) namely 81 versus 61 to 65 days. Second bone marrow infusions were needed in 6% and 20% of patients who received ATG doses of (40 versus 60 to 100 mg/kg; respectively (1 to 2 month post-BMT). BU at a dose of 15 mg/kg was more effective than 14 mg/kg BU for its myeloablative properties. By adding "short" ATG course to the conditioning regimen, the incidence of grade IV acute and chronic GVHD was reduced in thalassemic patients, especially when an HLA disparity was present.

Hypoplastic myelodysplastic syndromes can be distinguished from acquired aplastic anaemia by bone marrow stem cell expression of the tumour necrosis factor receptor

It is often difficult to distinguish hypoplastic myelodysplastic syndrome (h-MDS) from acquired aplastic anaemia (AA), because of the considerable clinical, cytological and histological similarities between these two disorders. The distinction between AA and h-MDS is important because there is a higher risk of progression to acute leukaemia in patients with h-MDS compared with AA. Recent studies suggest that tumour necrosis factor-alpha (TNF-alpha) plays an important role in the development of AA. In order to determine the potential importance of TNF-alpha in the differential diagnosis of hypoplastic bone marrow (BM) disorders, we examined whether analysis ofTNF-receptor expression could be used as a tool to differentiate AA from h-MDS. Flow cytometric analysis revealed that BM stem cells (CD34+) from AA patients have markedly greater TNF receptor (R) 1 and TNFR2 expression than those from patients with MDS and h-MDS. We suggest that the BM stem cells with a high expression of TNFR in patients with AA may be potently sensitive to TNF-alpha stimulation of differentiation. Thus, we propose that quantification of TNFR expression in BM stem cellsmay be a useful method to distinguish AA from h-MDS.

Cutting edge: activation of the p38 mitogen-activated protein kinase signaling pathway mediates cytokine-induced hemopoietic suppression in aplastic anemia

Myelosuppressive cytokines, in particular IFN-gamma and TNF-alpha, play an important role in the pathogenesis of idiopathic aplastic anemia in humans. It is unknown whether these negative regulators of hemopoiesis suppress stem cells by activating a common signaling cascade or via distinct nonoverlapping pathways. In this study, we provide evidence that a common element in signaling for IFN-gamma and TNF-alpha in human hemopoietic progenitors is the p38/MapKapK-2 signaling cascade. Our studies indicate that pharmacological inhibition of p38 reverses the suppressive effects of IFN-gamma and TNF-alpha on normal human bone marrow-derived erythroid and myeloid progenitors. Most importantly, inhibition of p38 strongly enhances hemopoietic progenitor colony formation from aplastic anemia bone marrows in vitro. Thus, p38 appears to play a critical role in the pathogenesis of aplastic anemia, suggesting that selective pharmacological inhibitors of this kinase may prove useful in the treatment of aplastic anemia and other cytokine-mediated bone marrow failure syndromes.

Immunosuppressive treatment of aplastic anemia with antithymocyte globulin and cyclosporine

Immunosuppression is the treatment modality for the majority of patients with aplastic anemia, most of whom are not candidates for allogeneic stem-cell transplantation. Antithymocyte globulin (ATG) or antilymphocyte globulin (ALG) have proven to be essential components of all regimens. Initial response rates can be improved by the addition of cyclosporine A (CsA), and this combination has become the standard of care for appropriate patients. Several new approaches to immunosuppression are being studied, including the optimal timing of administration of these drugs, the use of novel immunosuppressive agents, and the addition of early- and late-acting hematopoietic growth factors.

Cyclophosphamide and other new agents for the treatment of severe aplastic anemia

Severe aplastic anemia (SAA) has a poor prognosis in the absence of treatment. Current accepted therapeutic strategies include allogeneic stem-cell transplantation and immunosuppression, both resulting in long-term survival in the majority of patients. Although human leukocyte antigen (HLA)-matched sibling stem-cell transplantation is highly effective, the 25% probability of finding a suitable sibling donor within a family renders this approach available to only a minority of patients. Transplantation using HLA-matched, unrelated donors carries a high risk of treatment failure along with considerable toxicity. While combined immunosuppression with both antithymocyte globulin (ATG) and cyclosporine A (CSA) produces hematologic improvement in most patients, relapse is common. Late evolution of aplastic anemia to other serious hematologic disorders, including paroxysmal nocturnal hemoglobinuria (PNH), myelodysplasia, and acute leukemia, is also a significant problem following treatment with ATG/CSA. Recently, results of immunosuppression in SAA with another potent immunosuppressive agent, cyclophosphamide, were reported in a small number of patients. The overall response rate was similar to that seen with ATG/CSA, but relapse and late clonal disease were not observed during a long period of follow-up. A larger randomized trial comparing sustained hematologic response rates to either conventional immunosuppression with ATG/CSA or high-dose cyclophosphamide and CSA is now underway; secondary end points include response duration, event-free survival, and overall survival. Additionally, a number of protocols designed to test the efficacy of alternative immunosuppressive or immunomodulatory agents are being developed.

Delayed activation-induced T lymphocytes death in aplastic anemia: related with abnormal Fas system

OBJECTIVES

To quantitate apoptosis and Fas antigen expression of T lymphocytes by activation in aplastic anemia (AA) and compare with that of normal controls and completely-recovered AA, and to investigate the apoptotic sensitivity to anti-fas antibody of activated T lymphocytes in AA.

METHODS

We studied the expression of Fas antigen on fresh T lymphocytes of twenty patients with AA [13 newly diagnosed, 7 recorvered AA after immunosuppressive therapy (IST)], and investigated the activation-induced cell death (AICD) and Fas expression by activation [interleukin-2 (200 U/ml) and phytohemagglutinin (50 micrograms/ml)] in 5 newly-diagnosed AA, 5 normal controls and 5 AA in complete response (CR). Apoptotic sensitivity to anti-Fas antibody was assessed by the time-course kinetics of induction of cell death by anti-Fas antibody (500 ng/ml).

RESULTS

There was no significant difference of Fas antigen expression on freshly-isolated T lymphocytes among newly-diagnosed severe AA, normal controls and patients with AA in CR after IST. In normal controls, T lymphocytes death was greatly increased at 3 days of activation, and Fas antigen expression on T lymphocytes was increased above baseline at day 1 of activation. In contrast, in newly-diagnosed AA, T lymphocytes showed delayed cell death, which correlated with a slowed increase of Fas antigen expression by activation. Also, anti-Fas antibody sensitivity of activated T lymphocytes was decreased in newly-diagnosed AA. In completely recovered AA, these abnormal AICD and Fas antigen expressions by activation were recovered to normal range.

CONCLUSIONS

Abnormal AICD plays a role in the immune pathophysiology of AA, and defective Fas system is involved in this process.

Antithymocyte immunoglobulin in severe aplastic anemia and bone marrow transplantation

OBJECTIVE

To review antithymocyte immunoglobulin (ATG) and its current role in the treatment of severe aplastic anemia (SAA), focusing on ATG in immunosuppressive therapy compared with bone marrow transplantation (BMT).

DATA SOURCES

A MEDLINE search (1966 to 1996) of English-language literature and human subjects pertaining to ATG and BMT therapy in SAA was performed. Additional literature was obtained from reference lists of pertinent articles identified through the search.

STUDY SELECTION AND DATA EXTRACTION

All articles were considered for possible inclusion in the review. Pertinent information, as judged by the authors, was selected for discussion.

DATA SYNTHESIS

The hallmark of SAA is pancytopenia and bone marrow hypoplasia. Although the etiology in a majority of cases remains unknown, current data implicate an immune-mediated destruction of stem cells. ATG is a potent immunosuppressive agent and has emerged as an important therapy for patients with SAA. The exact mechanism of immunosuppressive action is not fully understood, although ATG appears to disrupt cell-mediated immune responses resulting in inhibition or altered T-cell function. Numerous trials have evaluated the use of ATG both as monotherapy and in combination with other immunosuppressive agents. Treatment with ATG in SAA has demonstrated a 40-70% response rate. Data suggest that intensive immunosuppressive therapy with ATG in combination with cyclosporine may provide the optimal immunosuppressive treatment. Questions still remain concerning complications and long-term survival of the patients. Although more than a 2-year follow-up shows a decline in mortality, a plateau in the survival curve was not achieved. BMT is a potential treatment for SAA. Although there is a high initial mortality due to treatment-related toxicities, successful marrow engraftment provides a cure for SAA. Many patients (75-90%) experience long-term survival after allogenic BMT. Age, donor availability, and severity of disease limit the number of eligible patients.

CONCLUSIONS

Due to excellent results with BMT, it has become the therapy of choice for selected patients with SAA. For patients who are not eligible for BMT, intensive immunosuppressive therapy with ATG and cyclosporine is recommended. Further study to better understand the pathogenesis of SAA and prevent treatment-related complications is essential to provide the best care to all patients.

Overproduction of inhibitory hematopoietic cytokines by lipopolysaccharide-activated peripheral blood mononuclear cells in patients with aplastic anemia

The aim of this study was to measure the level of cytokines produced by peripheral blood mononuclear cells (PBMNC) in patients with aplastic anemia (AA) and to determine their effect on the clonal growth of normal bone marrow (BM) cells. Twenty-one patients with AA and 11 normal controls were enrolled in this study. Medium conditioned by PBMNC of AA patients in the presence of lipopolysaccharide (LPS) was found to be suppressive to the colony growth of normal BM cells. Thus, we further determined the presence in the PBMNC-conditioned medium (CM) of both inhibitory cytokines: macrophage inflammatory protein-1 alpha (MIP-1 alpha), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta 2 (TGF-beta 2), and interferon-gamma (IFN-gamma), and stimulatory cytokines: interleukin-3 (IL-3) and stem cell factor (SCF). Spontaneous production of MIP-1 alpha was higher in the AA patients than the normal controls (1887 +/- 174 pg/ml vs 1643 +/- 93 pg/ml), but the difference was not significant. After LPS stimulation, the production of MIP-1 alpha was markedly increased in the AA patients, and its level was significantly higher than that of the normal controls (2360 +/- 149 pg/ml vs 1517 +/- 92 pg/ml, p = 0.0022). The level of TNF alpha was also higher in the AA patients. However, IFN-gamma, TGF-beta 2, SCF, and IL-3 were not detectable in the PBMNC-CM of either AA patients or normals. The myelopoietic suppressing effect of AA-PBMNC-CM from each AA patient was significantly blocked by pretreatment with anti-TNF-alpha, resulting in a colony-forming enhancement of 174% +/- 12%. A similar effect was noted in six of 11 AA patients by pretreatment with anti-MIP-1 alpha. We conclude that TNF alpha and MIP-1 alpha can be overproduced by the PBMNC of some AA patients, which may play a role in the progression of AA.

Analysis of lymphocyte subsets in patients with aplastic anemia before and during immunosuppressive therapy

To define the contribution of T-lymphocyte subsets in the development of aplastic anemia (AA), T-cell subpopulations including alpha beta T cells, gamma delta T cells, and delta TCS1-positive gamma delta T cells, were analyzed by cytophotometry in the peripheral blood (PB) and bone marrow (BM) of patients with AA before and after 6 weeks of therapy with anti-lymphocyte globulin (ALG), methylprednisolone, and cyclosporin A (CSA). In nine patients with AA a significant decrease of PB- and BM-derived T cells was observed after 6 weeks of therapy as compared with normal controls. At diagnosis, the CD4/CD8 ratio in PB and BM of the patients did not differ from the ratio in the control population; however, a reversed ratio (< 1) was present in PB as well as in BM after weeks of therapy. Interestingly, lymphocytes expressing the gamma delta T-cell receptor (TCR tau delta) were significantly decreased both before (PB 1.2 +/- 0.1%; BM 0.8 +/- 0.1%) and after 6 weeks of therapy (PB 0.7 +/- 0.1%; BM 0.7 +/- 0.1%) as compared with healthy controls (PB 2.4 +/- 0.2%; BM 2.3 +/- 0.2%). However, the proportion of the gamma delta-T-cell subpopulation expressing the delta TCS1 phenotype was markedly increased before (PB 42 +/- 3.5%; BM 31 +/- 3%) and especially after 42 days of therapy (PB 77 +/- 12%; BM 45 +/- 2%) as compared with that in normal subjects (PB 19 +/- 2%; BM 9.7 +/- 0.8%). At present, follow-up is under evaluation to correlate these findings with hematological response. The pathophysiological significance of the observed alterations within the T-cell subsets and especially the gamma delta T-cell populations will require further functional analyses, in particular since delta TCS1-positive gamma delta T cells exhibit autoimmunological capacity.

Aplastic anaemia: pathogenetic mechanisms and treatment with special reference to immunomodulation

Aplastic anaemia (AA) has been defined as a syndrome in which the presence of pancytopenia is accompanied by marrow hypocellularity. Ample laboratory data and clinical observations continue to make immune mediation of bone-marrow failure an attractive hypothesis. Recent progress in the practice of bone-marrow transplantation has led to a survival rate of approximately 80% in the best cases, but such a treatment is only amenable in young patients (less than 45-50 years) with HLA-identical bone-marrow donors. Anti-lymphocyte and thymocyte globulin treatment has been surprisingly effective for AA, resulting in transfusion independence in 40-80% of patients. The mechanism of action is unknown, although effects on immunosuppression appear to be the most likely candidates. Long-term results for patients receiving cyclosporin A treatment will soon be available, and preliminary data show an effect similar to that of antithymocyte globulin. In contrast to successful bone-marrow transplantation, improvement following immunomodulation leaves quantitative abnormalities in all haematopoietic cell lines, and patients are prone to develop clonal (malignant) disease.

A trial of recombinant human interleukin-1 in patients with severe refractory aplastic anaemia

We report here the effects of in vivo administration of recombinant interleukin-1 alpha (rIL-1 alpha) to patients with severe, idiopathic aplastic anaemia. Four patients who were refractory to immunosuppressive therapy and were not bone marrow transplantation candidates received daily doses of 0.03 microgram/kg and 0.10 microgram/kg intravenously as 5 d courses. No significant changes in either peripheral blood counts or bone marrow cellularity were observed at either dose during or following therapy. Two patients showed increased numbers of bone marrow progenitor colonies. Lymphocyte phenotyping demonstrated an elevated percentage of CD8+/DR+ activated suppressor T lymphocytes prior to therapy. After rIL-1 alpha administration, the percentage of CD8+/DR+ cells was reduced or returned to normal in all patients. Significant side-effects included fever, rigours, fatigue, headache and nausea. Transient hypotension was observed at both doses in all patients. These results suggest that while rIL-1 alpha can be safely administered, no significant haematologic improvement was observed in patients with severe aplastic anaemia.

Interleukin-1: biology, pathophysiology, and clinical prospects

Interleukin-1 (IL-1) is a cytokine with multiple biologic activities. Since its first description in 1972, significant work has been done, leading to an understanding of the biology of IL-1, which plays a central role in many important functions of the immune system. The biologic activities of IL-1 make it an attractive factor for use in clinical oncology, both as an antitumor agent and for the hematologic recovery of cancer patients receiving other forms of therapy. In this review the biologic effects of IL-1 are summarized. The possible involvement of IL-1 in the pathogenesis of some diseases is reviewed. Future prospects for the use of IL-1 in the treatment of malignancies are discussed.

Antilymphocyte globulin therapy enhances impaired function of natural killer cells and lymphokine activated killer cells in aplastic anaemia

MHC-unrestricted cytotoxic lymphocytes, namely natural killer (NK) and lymphokine activated killer (LAK) cells, have been implicated in the regulation of haemopoiesis. To investigate the possible role of these lymphocytes in the pathogenesis of aplastic anaemia (AA), we studied their functions in the peripheral blood mononuclear cells (PBMC) and bone marrow mononuclear cells (BMMC) of patients with AA treated with antilymphocyte globulin (ALG). Before treatment, both NK and LAK activities in the PBMC of 25 patients were low (NK = 1.9 +/- 2.1 x 10(3) LU/l) LAK = 4.7 +/- 3.6 x 10(3) LU/l) compared to normal (NK = 6.0 +/- 3.0 x 10(3) LU/l, LAK = 10.0 +/- 3.5 x 10(3) LU/l) or multiply transfused (NK = 7.8 +/- 6.6 x 10(3) LU/l, LAK = 25.2 +/- 13.6 x 10(3) LU/l) controls. The NK and LAK activities in the BMMC in AA patients were not significantly different from those in PBMC. In all patients with low LAK and NK activities pre ALG there was an increase in activity 2-24 weeks after therapy which eventually reached normal levels and which was maintained for up to 2 years. Analysis of lymphocyte phenotypes in AA patients before treatment showed both significantly low mean proportion and absolute numbers of CD16+ cells compared to normals, which increased after therapy. Changes in MHC-unrestricted cytotoxicity and lymphocyte phenotypes post therapy were not correlated with haemopoietic recovery. These data suggest that ALG treatment can enhance the functions of MHC-unrestricted lymphocytes independently from haemopoiesis. It is unlikely that these cells play a role in the pathogenesis of AA.

Different haematopoietic growth factors have different capacity in overcoming the in vitro interferon gamma-induced suppression of bone marrow progenitor cells

Interferon gamma (IFN gamma) inhibits haematopoiesis in vitro and an in vivo role in bone marrow suppression has been implied from clinical studies. We investigated the capacity of three recombinant (r), human (h), haematopoietic growth factors to overcome the in vitro IFN gamma inhibition of bone marrow progenitor cells in a methylcellulose culture system. Granulocyte macrophage-colony stimulating factor (GM-CSF) partially reversed IFN gamma-induced suppression of granulocyte-macrophage colony formation, by increasing colony forming units-granulocyte macrophage (CFU-GM) in a proportion ranging from 54-101%. Interleukin-3 (IL-3) and granulocyte-colony stimulating factor (G-CSF) were much less effective. For erythropoiesis, IL-3 was much more effective and partially reversed IFN gamma-mediated inhibition by increasing burst forming units-erythroid (BFU-E) in a proportion ranging from 52-138%. GM-CSF and G-CSF had no significant effect on IFN gamma-induced suppression of BFU-E. In conclusion, haematopoietic growth factors have different capacity to overcome IFN gamma-induced suppression of marrow progenitor cells in vitro. The findings may have therapeutic implications, as combinations of growth factors may be more effective in treating bone marrow failure syndromes.

Effect of antilymphocyte globulin (ALG) on bone marrow T/non-T cells from aplastic anaemia patients and normal controls

The aim of this study was twofold: (a) to test the effect of antilymphocyte globulin (ALG) on bone marrow (BM) T/non-T cells, and (b) to look for a possible differential response of cells from severe aplastic anaemia (SAA) patients and controls. For this purpose bone marrow T/non-T cells from normal individuals (n = 7) or aplastic patients (SAA, n = 13) were kept in liquid culture with or without ALG. Supernatants were then tested for enhancement/suppression on colony forming unit, granulocyte-macrophage (CFU-GM) growth (in the presence of exogenous recombinant granulocyte-macrophage colony stimulating factor (rGM-CSF)), or for their ability to support CFU-GM growth (in the absence of exogenous rGM-CSF). Supernatants from SAA T cells suppressed CFU-GM growth of normal bone marrow cells in 5/12 patients (mean expected growth (EG) 71 +/- 16%), but not after incubation with ALG (mean 110 +/- 29% EG, P = 0.03). No inhibition could be obtained with the supernatants from untreated normal T cells. Significant enhancement was seen with ALG treated versus untreated SAA T cells (142 +/- 28% EG v. 105 +/- 61% EG, P = 0.01) and with ALG treated versus untreated SAA non-T cells (165 +/- 26% EG v. 105 +/- 23% EG, P = 0.01), but not in controls. Supernatants from SAA and control T/non-T cells were capable of promoting colony formation in the absence of rGM-CSF (colony-stimulating activity (CSA) production): 16 +/- 14% for SAA-T cells and 19 +/- 18% EG for non-T cells (100% = 30 ng rGM-CSF/ml). The addition of ALG increased CSA production in T cells to 37 +/- 23% EG (P = 0.04) and in non-T cells to 40 +/- 13% EG (P = 0.04). Similar results could be obtained in controls.

IN CONCLUSION

(a) ALG interacts in vitro with bone marrow T and non-T cells from SAA patients, down-regulating the production of negative lymphokines and enhancing the release of haemopoietins; (b) the latter, but not the former effect, can be shown also with cells from normal controls. The two effects are not mutually exclusive, and are likely to provide maximal benefit in vivo.

Cyclosporine therapy of aplastic anaemia, congenital and acquired red cell aplasia

We treated 22 patients with severe aplastic anaemia refractory to antithymocyte globulin (ATG) with cyclosporine, alone or in combination with prednisone. Eight patients showed significant clinical improvement, all but one to transfusion-independence. Although cyclosporine alone was effective, the addition of prednisone resulted in prompter and fuller haematologic improvement. No patient with an absolute granulocyte count less than 0.2 x 10(9)/l responded to treatment. Haematologic remissions were sustained beyond the treatment period. Of nine patients with Diamond-Blackfan syndrome, one showed a complete response to two separate courses of cyclosporine and relapse with withdrawal of therapy, and a second achieved significant reduction in corticosteroid dose without relapse; however, seven cases failed to respond. Two of three adults with acquired pure red cell aplasia recovered. A combination of cyclosporine and corticosteroids may be effective therapy in patients with aplastic anaemia who have failed ATG treatment. Occasional cases of congenital and acquired pure red cell aplasia may also respond to cyclosporine.

Decreased interleukin 1 production in aplastic anaemia

Interleukin 1 (IL-1) is an important regulator of immune system function. IL 1 also affects haematopoiesis in vitro: it causes release of colony stimulating factors from fibroblasts and endothelial cells and can directly act on primitive haematopoietic stem cells. We investigated IL 1 production in vitro by stimulated peripheral blood mononuclear cells of patients with aplastic anaemia (N = 17), patients with other haematologic diseases (N = 27), and normal individuals (N = 22) using a bioassay for IL 1 activity. Ten aplastic patients showed markedly decreased IL 1 production. IL 1 production by fibronectin-affinity purified monocytes was decreased in six of seven of these patients; in three other cases, in which IL 1 mononuclear cell production was undetectable, sufficient monocytes could not be isolated. IL 1 alpha and IL 1 beta precursor molecules were also absent or much decreased when mononuclear cell lysates from these patients were analysed by immunoblot using specific polyclonal sera. Aplastic patients with low IL 1 production were distinguished by the severity of their disease and the degree of neutropenia. Patients with myelodysplasia with comparable degrees of pancytopenia had normal IL 1 production. This is the first example of deficient haematopoietic growth factor production in a bone marrow failure syndrome. Decreased IL 1 production may contribute to the pathogenesis of some cases of aplastic anaemia and to susceptibility to infection.

Identification of activated T cells and the suppressor/inducer subset in patients suffering from severe aplastic anemia

In patients with severe aplastic anemia (SAA), lymphocyte subpopulations were examined for the presence of HLA-DR and 2H4 (suppressor/inducer subset) antigen-expressing cells by flow cytometric analysis. Investigations were performed on peripheral blood lymphocytes before and after therapy with antithymocyte globulin (ATG) and methylprednisolone (MP), as well as on bone-marrow lymphocytes before therapy. Before treatment, only the absolute numbers of CD4+ T cells and the CD4+HLA-DR+/CD8+HLA-DR+ activated T cell ratio were significantly decreased (p less than 0.01 and p less than 0.001, respectively). Following successful ATG/MP treatment, a decrease in the CD4+/CD8+ T cell ratio was found. Regarding the suppressor/inducer subset, only absolute numbers of CD4+/2H4+ cells were somewhat higher in treated patients; the percentages were the same in all groups of patients. Studies performed on bone-marrow lymphocytes showed significantly decreased percentages of CD4+ and CD8+ T lymphocytes, which also express HLA-DR antigen. No significant changes in the distribution of activated T cells following ATG/MP therapy were found, suggesting that these cells play no major role in the pathogenesis of the disease.

Decreased interleukin-1 production in aplastic anemia

PURPOSE

Interleukin-1 (IL-1), a monocyte factor, plays a central role in the regulation of the immune response; recent data have suggested that IL-1 is the same molecule as hemopoietin-1, a growth factor acting on the multipotent hematopoietic stem cell. IL-1 affects hematopoiesis (1) in vitro, by inducing the release of colony-stimulating factors and regulating early hematopoietic progenitor cells, and (2) in vivo, by stimulating stem cell recovery in irradiated or chemotherapy-treated mice. Several lines of evidence suggest that aplastic anemia may be mediated by cells of the immune system. We address the issue of abnormal IL-1 production in severe aplastic anemia and attempt to correlate normalization of the levels with response to anti-thymocyte globulin (ATG) therapy.

PATIENTS AND METHODS

We studied IL-1 production by monocytes from 21 patients with aplastic anemia using a bioassay for IL-1 activity. Fifteen patients were evaluated before ATG therapy. Eight patients were studied before and three months after ATG. In addition, five patients were evaluated only after ATG treatment. One patient did not respond to ATG but did respond to intravenous acyclovir, and was studied before and after acyclovir therapy. Twenty patients with other hematologic disorders requiring transfusions and 30 normal healthy volunteers were also assessed.

RESULTS

IL-1 production was markedly decreased in 75 percent of patients with aplastic anemia when compared with that in normal control subjects (p less than 0.005). Hematologic recovery correlated with normalization of IL-1 production in all but two cases (p less than 0.04).

CONCLUSION

These observations represent the first evidence of monocyte dysfunction and deficient hematopoietic growth factor production in aplastic anemia. Decreased IL-1 production may have a pathologic role in some cases of aplastic anemia.

Phenotypic and functional T cell subset abnormalities in patients with aplastic anaemia and hypogammaglobulinaemia

We have investigated T cell abnormalities present in blood of two patients with aplastic anaemia and hypogammaglobulinaemia. There was a marked increase in class II, major histocompatibility complex, HLA-DR+ antigen, and interleukin-2 receptor (Tac+) bearing CD4+ helper/inducer T cells, and a concurrent reduction of CD8+ suppressor/cytotoxic T cells. These CD4+ T cells produced an elevated proliferative response to phytohaemagglutinin and concanavalin A. Interestingly, the T cell subset mainly responsible for elevated production of the lymphokine, interleukin-2, under the stimulus of phytohaemagglutinin, was characterized as belonging to a CD4+ T cell subset. Functional studies, using a pokeweed mitogen driven IgG, IgA and IgM synthesis, demonstrated a correlation between CD4+ T cell deficient helper function for B cell differentiation and the clinical finding of the patient's hypogammaglobulinaemia.

The role of antilymphocyte globulin in the treatment of chronic acquired bone marrow failure

Antilymphocyte globulin is an immunoglobulin preparation prepared from heterologous serum after the animal (horse or rabbit) has been immunised with human lymphocytes, obtained from the thymus (antithymocyte globulin, ATG) or thoracic duct (antilymphocyte globulin, ALG). The rationale for the use of ALG in the treatment of chronic acquired marrow failure is based on its immunosuppressive activity and the fact that a proportion of cases of bone marrow failure, whether affecting single or multiple haemopoietic cell lines are due to immune-mediated suppression of haemopoiesis. In addition, in vitro studies have shown that ALG also has an immunostimulatory effect on lymphokine and haemopoietic growth factor production, and may therefore directly stimulate haemopoietic progenitor cells. ALG has been used for the treatment of aplastic anaemia and acquired chronic marrow failure affecting single cell lines namely pure red cell aplasia (PRCA), amegakaryocytic thrombocytopenia and chronic neutropenia due to immune inhibition of granulopoiesis ('acquired white cell aplasia'). ALG is used for treatment of non-severe aplastic anaemia (NSAA) and in those cases of severe aplastic anaemia (SAA) where allogeneic transplantation is not possible or is not indicated. Treatment with ALG results in 75% long term survival for NSAA and 40-50% for SAA although there is a very severe subgroup of SAA defined by peripheral blood neutrophils of less than 0.2 x 10(9)/l who rarely benefit from ALG therapy. For those patients who do not respond a second course of ALG can be given later using ALG from a different animal source.(ABSTRACT TRUNCATED AT 250 WORDS)