Severe aplastic anaemia: correlation of in vitro test with clinical response to immunosuppression in 20 patients

Intracellular interferon-gamma in circulating and marrow T cells detected by flow cytometry and the response to immunosuppressive therapy in patients with aplastic anemia

Immunosuppressive therapy leads to meaningful hematologic improvement in most patients with aplastic anemia (AA). Failure to respond and a later relapse could be due to deficient numbers of hematopoietic stem cells, inadequate treatment of the immune process, or a nonimmunologic etiology. Interferon-gamma (IFN-gamma) has been implicated in the pathophysiology of hematopoietic failure in AA. On the basis of previous findings showing overexpression of IFN-gamma in bone marrow (BM) and peripheral blood (PB) in this disease, we hypothesized that quantitation of IFN-gamma might be applied to predict and monitor responses to immunosuppressive therapy. We measured expression of IFN-gamma in lymphocytes obtained from 123 AA patients, using intracellular 2-color fluorescent staining and flow cytometry. Of 70 patients with severe AA, 36 (51%) demonstrated increased IFN-gamma in circulating T cells. IFN-gamma was detected in only 4 of 53 patients who had recovered from AA. IFN-gamma was not found in PB lymphocytes of patients with other hematologic diseases and heavy transfusion burdens or in healthy volunteers. Among 62 AA patients who were assessed before first treatment with immunosuppressive drugs, 27 of 28 (96%) with circulating IFN-gamma-containing T cells subsequently responded to therapy; in contrast, only 11 of 34 (32%) patients whose PB lacked IFN-gamma lymphocytes improved to transfusion independence. IFN-gamma-containing lymphocytes declined following treatment in all cases. Of 17 patients assessed during relapse, IFN-gamma was present in T cells prior to the blood count decline in 13, and 12 responded to reinstitution of immunosuppressive drugs. Of 30 BMs tested prior to first treatment, 20, all in responding patients, were positive for IFN-gamma, whereas the negative tests were obtained in 10 nonresponding patients. IFN-gamma is increased in the PB lymphocytes of many patients with AA, and these cells decline with therapy. The presence of intracellular IFN-gamma may predict response to immunosuppressive treatment and also the onset of relapse.

Immunosuppressive treatment of acquired aplastic anemia and immune-mediated bone marrow failure syndromes

Modern therapeutic strategies for the treatment of acquired aplastic anemia are based on the current understanding of its pathophysiology as well as empiric observations. Most cases of aplastic anemia appear to be the result of immune-mediated destruction of hematopoietic cells, which can be approached by stem cell transplantation in younger patients with appropriate histocompatible donors or by immunosuppression to reduce T-cell activity. Popular treatment regimens combine antithymocyte globulin with cyclosporine. Although a majority of patients respond with improved blood counts and achieve transfusion-independence, late clonal complications of myelodysplasia and cytogenetic abnormalities occur in a substantial minority of cases. Additionally, there is no clear algorithm for the treatment of refractory disease. Newer methods of treatment, including high-dose cyclophosphamide and the development of potentially tolerizing combinations of drugs. are under study. Effective therapies for aplastic anemia might also be applied to other T-cell mediated, organ-specific human diseases.

Aplastic anaemia: management

Acquired, idiosyncratic aplastic anaemia (AA) is a rare but potentially fatal haematological disorder. Severe AA constitutes an acute medical emergency, and supportive therapy is needed to prevent overwhelming sepsis or a life threatening haemorrhage. Specific therapy for the disease includes the choice between allogeneic stem cell transplantation (SCT) from an HLA-identical sibling or immunosuppressive therapy with anti-thymocyte globulin (ATG) and cyclosporin A (CSA). Long-term cure rates of 75-90% are now achieved following HLA (human leukocyte antigen) identical sibling bone marrow transplant. The use of donors other than HLA-id siblings for transplantation in AA remains experimental. Transplantation offers the patient a chance of cure, whilst treatment with immunosuppressive therapy carries a long-term risk of relapse and clonal transformation. The haemopoietic growth factors, apart from granulocyte colony stimulating factor (G-CSF), have been shown to be potentially toxic when given to patients with AA. A short course of G-CSF may be useful to help treat severe infection, but its longer-term use with ATG and CSA remains controversial. Results from immunosuppressive treatment continue to improve with time, as a result of the additional use of CSA with ATG, the use of repeat courses of ATG for non-responders and improvements in the supportive care of patients.

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.

High-dose intravenous methylprednisolone therapy for patients with Diamond-Blackfan anemia refractory to conventional doses of prednisone

OBJECTIVES

To assess the efficacy and toxicity of very high doses of glucocorticoids in patients with congenital pure red cell aplasia (Diamond-Blackfan anemia) who did not respond to standard doses of prednisone.

STUDY DESIGNS

We prospectively treated eight patients with transfusion-dependent Diamond-Blackfan anemia with high intravenous doses of methylprednisolone. All patients had previously not responded to one or more oral courses of prednisone in standard doses and were dependent on erythrocyte transfusions. Every patient initially received methylprednisolone at a dose of 30 mg/kg per day, followed by slow tapering for 4 weeks, but none responded. All patients then received a second treatment course starting at 100 mg of methylprednisolone per kilogram per day, again followed by slow tapering of the dosage.

RESULTS

Three patients had a complete response that has been sustained for 21+, 31+, and 41+ months, respectively. One patient had a partial response. Toxic effects included a rise in serum alanine aminotransferase activity in all patients, transient diabetes mellitus in one child, and three episodes of bacteremia in two patients with intravenous access devices.

CONCLUSIONS

We conclude that very high doses of methylprednisolone may induce sustained remission in some patients with transfusion-dependent Diamond-Blackfan anemia refractory to standard-dose prednisone therapy.

Treatment of aplastic anemia with antilymphocyte globulin and methylprednisolone with or without cyclosporine. The German Aplastic Anemia Study Group

BACKGROUND AND METHODS

Immunosuppression is the most effective treatment for patients with aplastic anemia, except for bone marrow transplantation. The best results are achieved with antilymphocyte globulin or cyclosporine. Patients have been treated successfully with a combination of both agents, but there has been no controlled evaluation of its efficacy. We conducted a randomized, multicenter trial in 84 patients not eligible for bone marrow transplantation, comparing treatment with antilymphocyte globulin and methylprednisolone (41 patients--the control group) with antilymphocyte globulin, methylprednisolone, and cyclosporine (43 patients--the cyclosporine group).

RESULTS

At three months significantly more patients in the cyclosporine group had a complete or partial remission in response to treatment than did patients in the control group (65 percent vs. 39 percent, P less than 0.03); this difference was confirmed at six months (70 percent vs. 46 percent, P less than 0.05). The superior results of the regimen including cyclosporine were most evident in the patients with severe or very severe aplastic anemia, whose response rate at six months was 65 percent, as compared with 31 percent of such patients in the control group (P less than 0.02). Granulocyte and hemoglobin levels became normal in most patients who responded, but platelet counts continued to be subnormal in 61 percent of the patients. Ten of 52 patients with responses (3 in the cyclosporine group and 7 in the control group) relapsed 4 to 37 months after treatment. The actuarial survival of all patients at 41 months is 64 percent in the cyclosporine group and 58 percent in the control group (P = 0.16); among the patients with severe or very severe disease, survival is 80 percent and 44 percent, respectively (P = 0.077). Cyclosporine had substantial but reversible side effects.

CONCLUSIONS

Immunosuppressive treatment of aplastic anemia with antilymphocyte globulin, methylprednisolone, and cyclosporine appears to be more effective than a regimen of antilymphocyte globulin and methylprednisolone without cyclosporine and may thus represent a treatment of choice for patients who are not eligible for bone marrow transplantation.

Treatment of pure red-cell aplasia and aplastic anaemia with ciclosporin: long-term clinical effects

6 patients with pure red-cell aplasia were treated with Ciclosporin (Cyclosporine A; CS) alone or combined with prednisolone for a period of 9-46 (median 27) months. Prior to study, 5 cases had refractory disease, steroids were contraindicated in 1, and 4/6 patients, including 2 cases with congenital disease, had a disease duration exceeding 11 years. A complete haematological response was obtained in 5/6 subjects, and a partial response in 1. When the pre-treatment Hb levels (mean +/- S.D. = 64 +/- 13 g/l, range 41-80) for all 6 PRCA patients were compared with the Hb levels after 6 months of CS therapy (104 +/- 17 g/l, 80-125), a significant improvement was registered (p less than 0.005). In half of the patients, remission is maintained with CS as single drug in a dose-dependent manner. We also treated 5 patients with refractory severe aplastic anaemia with CS (1 case) or CS plus prednisolone (4 cases) for 3-27 (median 10) months. Only 1 patient responded. In this case, a complete haematological remission was induced with CS alone, and remission has been maintained for 27 months. Side effects of CS therapy were common but were dose-dependent and reversible, with the exception of persistent nephrotoxicity in 1 patient with pure red-cell aplasia. Based on our present results and a survey of the literature, we conclude that CS therapy is effective and indicated in refractory pure red-cell aplasia. In severe aplastic anaemia resistant to conventional immunosuppression, the response rate is lower, but a small proportion (around 15%) of patients may benefit from CS therapy. Longer treatment periods may, however, be needed to evaluate the role of CS in aplastic anaemia.

Pathophysiology of aplastic anaemia

No single pathophysiological phenomenon--neither the intrinsic defect of haemopoiesis nor any of the described immune effects--explains aplastic anaemia. Since the intrinsic defect is compatible with near normal haemopoietic function, as seen in autologous bone marrow reconstitution, it cannot be the cause of severe pancytopenia. On the other hand, immune mechanisms cannot be the primary cause of the disease, otherwise haemopoietic function would recover to complete normality after immunosuppressive therapy. From these observations we deduce that the intrinsic defect, a premalignant haemopoietic disorder, can either be clinically quiescent by virtue of repair mechanisms, or induce auto-reactivity of the immune system against the abnormal haemopoietic tissue, drugs, chemicals and viruses acting as non-specific triggers or amplifiers. In this sense, aplastic anaemia could be interpreted as an attempt to 'self-cure' from a variant type of preleukaemia. This means that the original concept of aplastic anaemia being a hypoplastic variant of leukaemia may be true. The fact that aplastic anaemia can present either as acute severe bone marrow failure, as chronic mild pancytopenia or as a myelodysplasia-like syndrome does not imply that the underlying pathophysiological mechanisms are basically different. Variations of the clinical course and the response to immunosuppressive treatment could be explained by variations in the balance between the primary defect and the secondary immune reaction; the co-involvement of accessory cells in the primary disease; the relative time course of the two components and the efficiency of repair mechanisms. From repeated in vitro studies in a large group of aplastic anaemia patients at various stages of disease this concept can be applied to the majority of cases, including chloramphenicol- and virus-induced aplastic anaemia. In a small proportion of patients with pancytopenia occurring after exposure to certain drugs other than chloramphenicol, aplastic anaemia is rapidly and completely reversible after withdrawal of the drug. These patients probably have truly benign aplastic anaemia and thus differ from the majority of patients who are left with a permanently fragile bone marrow once they have acquired aplastic anaemia.

Methylprednisolone therapy in aplastic anaemia: correlation of in vitro tests and lymphocyte subsets with clinical response

20 patients with aplastic anaemia were treated with methylprednisolone 1 g/d for 3 d followed by prednisolone 60 mg on alternate days. At 3 months after therapy, 7 of 20 patients (35%) showed recovery, 2 had died and 11 were non-responders. Only newly diagnosed patients were responders. Results of in vitro tests were correlated with clinical response. The first test was designed to determine whether removing various subpopulation of cells would increase the numbers of progenitor cells. In the second test blood cells were collected at 1 month after starting treatment and assayed for progenitor cells. Data from both tests did not correlate with the response to therapy. Lymphocyte subsets were measured in the blood before and at 1 month after treatment. The absolute numbers of OKT3+, OKT4+ and OKT8+ cells were significantly decreased compared to the normal population. The number of HNK1+ cells was also decreased but no significant difference was observed. Responders had a higher number of HNK1+ cells compared to non-responders. No significant differences of OKT3+, OKT4+ and OKT8+ cells among responders and non-responders were observed. Therefore a high number of HNK1+ cells prior to therapy may identify patients responding to the treatment.

Do bone marrow fat cells or their precursors have a pathogenic role in idiopathic aplastic anaemia?

Idiopathic aplastic anaemia (AA), aplastic anaemia of unknown aetiology, is usually defined as marrow failure with fatty replacement of hemopoietic tissue and peripheral pancytopenia. The pathophysiology is largely unknown, though many mechanisms have been hypothesized. These include the absence of or defects in hemopoietic stem cells (HSC), abnormalities of the bone marrow (BM) microenvironment, immune system disorders and abnormalities of the regulatory factors that control hemopoiesis. The characteristic feature of AA is the replacement of hematopoietically active marrow by fat cells; however, the fat cells themselves have received little attention to date, and this apparent fatty marrow infiltration has been considered a secondary phenomenon. That the marrow fat cells in AA may be abnormal and may have a pathogenic role has never been considered. This communication, postulates that AA may result from an abnormal and excessive proliferation of marrow fat cells and the displacement of the hematopoietic tissue of the marrow; and that the resultant marrow failure could be a secondary phenomenon.

Effect of androgens on the response to antithymocyte globulin in patients with aplastic anaemia

30 patients with aplastic anaemia (18/30 with severe aplastic anaemia) were prospectively randomized to be treated with 100 mg/kg ATG with or without the oral androgen Methenolone (3 mg/kg). 15 of 30 patients responded. Among the 15 patients receiving ATG plus androgen, 11 patients (73%) responded, including 8 complete and 3 partial responses. 4 of the 15 patients (31%) receiving ATG only responded, including 2 complete and 2 partial responses. The difference in response rate was statistically significant (p = 0.01). The survival rate in the total population of 30 patients was 64%. The survival rate in the group receiving ATG plus androgen was 87%; in the group receiving ATG only it was 43%. The difference in survival rates between both groups did not reach statistical significance (p = 0.15). Toxicity of ATG and androgens was considerable but manageable. These data support the result of the recent European reevaluation of a large pool of patients by the EBMT (39), that androgens in addition to ATG increase survival in patients with aplastic anaemia. They are, however, in contradiction to a controlled American study showing no benefit of a combined treatment with androgens as compared to ATG only. Further controlled studies on a larger number of patients are indicated to determine the therapeutic efficacy of androgens in addition to immunosuppression in aplastic anaemia.

Immunostimulatory effects of different antilymphocyte globulin preparations: a possible clue to their clinical effect

Antilymphocyte globulin (ALG) and antithymocyte globulin (ATG) have an established role in the treatment of severe aplastic anaemia. The response rate ranges from 40% to 80%. Its mode of action is believed to be complement dependent lysis of immunocompetent cells which inhibit haemopoietic maturation. This might not be the sole mechanism. We have tested four different preparations of ALG/ATG for their mitogenic effect on normal peripheral blood cells and on enriched T-cells in vitro by 3H-thymidine incorporation. We found marked differences between the four preparations. One was strongly mitogenic and able to induce profound release of haemopoietic growth factors. This mitogenic effect could be detected in the serum of patients during ALG treatment. Clinical response rates of this preparation are about 80%. Three other preparations were of lower or no stimulatory effect. Clinical response rates with these preparations vary between 40% and 60%. From our results, we postulate that the beneficial effect of ALG could be partially due to its ability to stimulate release of haemopoietic growth factors. The mitogenicity of different ALG/ATG preparations should be tested as an in vitro parameter of clinical efficacy.

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

Twenty-two patients with adult onset aplastic anaemia were analysed before and after therapy with anti-thymocyte globulin (ATG). Lymphocyte phenotype, lymphokine levels or production, and haematopoietic progenitor cell number were measured 3 months after therapy; clinical response was determined 1 year post-therapy. By flow cytometry there was a significant reduction in both the proportion and absolute number of peripheral blood lymphocytes expressing activation antigen Tac (IL-2 receptor) and in the proportion of HLA-DR+ lymphocytes. For T cells bearing HLA-DR, there were proportional decreases in both activated helper and suppressor cells. There was no statistically significant difference pre-ATG to post-ATG in the absolute numbers of total, helper and suppressor lymphocytes. In all 10 haematologic responders the number of Tac bearing lymphocytes after ATG therapy was in the normal range, but half of 12 non-responding patients continued to have abnormally elevated numbers of Tac+ T cells. The proportion of Tac+ cells were not related to transfusion history. Gamma-interferon levels in serum by radioimmunoassay were elevated in almost half the aplastic patients; post-ATG, gamma-interferon was detectable in only three patients. Haematologic response to ATG therapy was associated with increased numbers of haematopoietic progenitors post-treatment, but pre-treatment values were not predictive of a response. These results are consistent with a pathogenic role for activated T-cells and their lymphokine products and suggest that the target of ATG therapy may be a Tac+ lymphocyte.

Progressive preleukemia presenting amegakaryocytic thrombocytopenic purpura: association of the 5q- syndrome with a decreased megakaryocytic colony formation and a defective production of Meg-CSF

The authors present a patient with the typical clinical picture of an acquired amegakaryocytic thrombocytopenic purpura. After 16 months of observation, the patient developed acute myelomonocytic leukemia. During the preleukemic phase and after progression to overt leukemia, serial in-vitro analyses of megakaryocytic, granulocytic, erythrocytic and T-lymphocytic colony growth were carried out in a microagar culture system. At presentation, a marked diminution of CFU-M was observed, whereas CFU-E, BFU-E, CFU-C and CFU-TL were in the normal range. The CFU-M number remained at its low level during the whole observation period. The CFU-C number declined steadily during the preleukemic period, while BFU-E, CFU-E and CFU-TL remained constant until January 1985 when the patient developed AML. After progression to overt leukemia, a distinct reduction became evident in all colony-forming cells. Cytogenetic studies performed during the preleukemic phase indicated the presence of a 5q- chromosome. The authors submit evidence here that the patient was not only characterized by defective megakaryocytic colony formation but also by a deficiency of functional megakaryocyte colony-stimulating activity. No humoral or cellular inhibitors of CFU-M colony formation were found. It is concluded that in preleukemia with a 5q- chromosome the megakaryocytic cell lineage may be involved in the process that precedes overt leukemia at an earlier time than cells of granulocytic and erythrocytic lineages. In addition, it is shown here that megakaryocytopoiesis during the preleukemic period can be characterized by two different defects: first, an intrinsic megakaryocytic stem cell defect and, second, a deficiency of functional megakaryocytic colony-stimulating activity.

Treatment of aplastic anemia with cyclosporin A, methylprednisolone, and antithymocyte globulin

Twenty-three patients with aplastic anemia (18/23 with severe aplastic anemia) were treated with an immunosuppressive regimen consisting of cyclosporin A (CsA) and methylprednisolone (MP) (n = 7) or CsA, MP, and antithymocyte globulin (ATG; n = 16). Nineteen patients are alive with a follow-up of 4 to 25 months; three patients died of infections and one of a gastrointestinal hemorrhage. Within 3 months, improvement of hematopoiesis was seen in 14 patients (61%). First signs of a response after 23 to 88 days were followed by complete remission in eight patients, partial remission in three patients, and minimal improvement in three patients. Two of the patients with only minimal improvement were treated with a second course of immunosuppression and reached a complete remission and partial remission. Interestingly, remission proved to be dependent on the continued administration of CsA in four of five patients with partial or complete remission who could be evaluated up to now. Thus, CsA must have been effective in the induction and/or maintenance of remission in three patients. This observation is a very strong argument for the role of T cells in the pathogenesis of at least some cases of aplastic anemia and warrants further evaluation of the role of CsA in the treatment of aplastic anemia.

Serum sickness and haematopoietic recovery with antithymocyte globulin in bone marrow failure patients

We have evaluated 33 patients with various bone marrow dyscrasias treated with horse antithymocyte globulin (ATG) (Upjohn) to determine the relationship of haematopoietic response to the occurrence of serum sickness. Patients received ATG intravenously over 10 or 28 d at a dose of 15 mg/kg/d. Total or partial haematological responses were noted in 12 of 33 patients. Twenty-eight patients developed clinical signs of serum sickness 6-14 d after the first infusion of ATG, while five patients did not. Twenty-five of these patients were evaluated by immunochemical assays for circulating immune complexes (C1q-binding assay) and 21 patients for serum complement (C3, C4 and CH50 assay) levels. There was a direct correlation between increases in immune complex levels, decreases in serum complement levels, and the development of the clinical signs and symptoms and serum sickness. Twenty-one of 28 patients who developed serum sickness failed to show haematological improvement. However, haematopoietic recovery occurred in all five patients who did not manifest serum sickness (P less than 0.05) and in four patients who failed to develop immune complexes. These findings indicate that the development of serum sickness is not required for a haematopoietic response with ATG and may indeed impair recovery.

T cell-mediated inhibition of haematopoiesis in aplastic anaemia: serial assay of inhibitory activities of T cells to autologous CFU-E during immunosuppressive therapy

T cell-mediated inhibition of autologous erythroid colony formation was found in two patients with aplastic anaemia. Each patient was treated separately with ALG and methylprednisolone. Peripheral blood T cells were cryopreserved serially during the course of the disease. The inhibitory activity of T cells was assayed after remission using autologous bone marrow. The inhibitory activity of T cells was lost following the treatment and preceded haematopoietic recovery.

Lack of correlation between in vitro corticosteroid effect on hemopoietic colony formation and response to corticosteroid therapy in aplastic anemia

We performed hemopoietic colony culture assays in 15 patients with aplastic anemia (AA) in order to test the effect of hydrocortisone (HC) on late erythroid colony (CFU-e) formation of the patients' marrow and to correlate the in vitro culture results with the clinical response to corticosteroid therapy. HC enhanced CFU-e growth in four patients. All four patients failed to respond to corticosteroid, but three improved with with androgens. The addition of HC did not increase CFU-e colony formation in 11 patients. However, two of them responded to corticosteroid therapy. Among the nine patients showing no HC effect in vitro, two subsequently improved with androgens and one each with anti-thymocyte globulin and anti-lymphocyte globulin. The results suggest that the in vitro corticosteroid effect may not necessarily correlate with responsiveness to corticosteroid therapy.

Inhibitory effect of PWM-stimulated OKT4+ subsets on erythro-, granulo- and megakaryocytopoiesis in vitro

Normal human peripheral blood T cells and T-cell subsets defined by monoclonal antibodies of the OKT series were pretreated with pokeweed mitogen (PWM). Their effects on the haematopoietic precursors, erythroid (BFU-E, CFU-E), granulocyte-macrophage (CFU-GM) and megakaryocyte (CFU-M) colony forming cells were evaluated by coculture. While unstimulated T cells and T-cell subsets enhanced growth of autologous blood BFU-E, PWM-stimulated T and OKT4+ cells suppressed it, also inhibiting proliferation of both autologous and allogeneic bone marrow BFU-E, CFU-E, CFU-GM and CFU-M. PWM-stimulated OKT8+ cells had little effect on the growth of any of the precursors at the cell concentration at which growth was completely inhibited by PWM-stimulated OKT4+ cells. Irradiation of T or OKT4+ cells with 3000 rad before PWM stimulation completely abrogated the inhibition. These observations might be related to the mechanism of pancytopenia in some cases of immune-mediated aplastic anaemia.

Stimulatory serum factors in aplastic anaemia. II. Prognostic significance for patients treated with high dose immunosuppression

Serum from patients with aplastic anaemia contains two distinct stimulatory activities on haemopoiesis in culture. The first is a highly unstable enhancing activity, which mainly stimulates colony formation from BFU-E and macrophage precursors, and only acts when added directly to target bone marrow cultures. It is destroyed by Sephadex G-150 chromatography, and thus differs from colony stimulating activity (CSA) and burst promoting activity (BPA). Its mode of action is unknown. It was elevated in 70/97 patients with severe aplastic anaemia (SAA). 71 of these 97 patients were treated with high dose immunosuppression. 55/71 who achieved self-sustaining haemopoiesis had higher serum stimulating activity on BFU-E than 16/71 who never achieved remission (P = 0.0004). It was predictive of response as an all or none phenomenon, independent of the time required for recovery. It was, however, unsatisfactory as a single prognostic test. Bone marrow reconstitution also occurred in 4/71 patients whose serum inhibited BFU-E in direct culture. The second stimulator acts via enhancement of CSA- and BPA-release by accessory cells and is therefore termed 'releaser' activity. It was elevated in 27 of 51 aplastic anaemia patients and did not correlate with direct stimulatory activity. High 'releaser' activity was not predictive of response in 42 patients treated with high dose immunosuppression. However, the ability of patient cells to respond to autologous 'releaser' activity was a positive risk factor. Patients whose cells released an excess of CSA in the presence of autologous serum had a significantly higher chance of autologous recovery within 3 months than patients who produced little or no CSA in the presence of normal or excess releaser activity (P less than 0.0001). A scoring system which includes these two good risk factors is proposed for estimation of a patient's probability to recover autologous bone marrow reconstitution.

Cyclosporin A in the treatment of severe acute aplastic anaemia

Twelve consecutive adults with severe acute aplastic anaemia, not having a bone marrow transplantation option, were prospectively randomized to receive either cyclosporin A alone or an equivalent amount of this immunosuppressive agent in combination with antilymphocyte serum. The minimum follow-up is 36 months, with half the patients developing nephrotoxicity, which was easily reversible in all but one. No response could be attributed to either regimen. Cyclosporin A does not appear to have a place as primary form of treatment for adults with severe acute aplastic anaemia, either on its own or in combination with antilymphocyte serum.

Interferon-induced aplasia: evidence for T-cell-mediated suppression of hematopoiesis and recovery after treatment with horse antihuman thymocyte globulin

A severe and persistent pancytopenia occurred in a 42-year-old woman with a non-Hodgkin's lymphoma following a 10-day course of intramuscular human leukocyte alpha interferon (IFN, 9.0 IU/day). Within 2 weeks of IFN, marrow nucleated myeloid and erythroid precursor cells and megakaryocytes were nearly absent and marrow progenitor cells (CFU-E, BFU-E, CFU-GM) were undetectable. Analysis of marrow lymphocytes revealed that nearly 50% of the cells were E-rosette+, T gamma+, OKT8+ (suppressor/cytotoxic) T-and/or Leu 7+ natural killer (NK) lymphocytes and 50% were IgM Kappa, B1+, B-lymphocytes. In vitro erythroid culture studies were consistent with T-cell-mediated suppression of erythropoiesis. After 2 months without improvement on corticosteroid/androgen therapy, a 10-day course of intravenous antithymocyte globulin (ATG) was administered. This was followed by a prompt reticulocytosis and a rise in blood neutrophils. After ATG therapy, there was a sixfold reduction in marrow suppressor cells, loss of in vitro suppressor effects on erythroid progenitor cells, and complete reversal of blood and marrow OKT4/OKT8 (helper/suppressor) ratios. These studies suggest that interferon may suppress hematopoiesis in some patients by activating marrow suppressor T- and/or NK cells. Treatment aimed at reduction of marrow suppressor cells may aid in hematologic recovery without eliminating the infiltrating lymphoma.

Pathogenesis of graft-versus-host reactions (GVHR) and GVH-like diseases

The graft-versus-host reaction (GVHR) in both mice and humans can lead to the development of a broad spectrum of clinical and pathological symptoms. These symptoms are strikingly similar to those of a number of diseases of proven or presumed immunological origin, such as systemic lupus erythematosus (SLE), other collagen vascular diseases, lymphoproliferative disease, and aplastic anemia. The purpose of our investigation was to describe the immunological and pathological events that take place in the course of graft-versus-host disease (GVHD) and to gain insight into the cellular mechanisms underlying these events. To this end, a model was employed in which nonirradiated F1 mice were used as recipients of parental lymphoid cells. By pathological manifestations, 2 basic forms of GVHD can be distinguished in such non-irradiated F1 recipients: One is acute GVHD which is often lethal. It is characterized by a variety of suppressive (hypoplastic) pathological symptoms, including a severe hypoplasia of the lymphohemopoietic system accompanied by aplastic anemia and hypogammaglobulinemia. The other basic form is characterized by stimulatory symptoms, such as persistent lymphoid hyperplasia, formation of autoantibodies, and development of pathological symptoms reminiscent of SLE and other collagen vascular diseases. The suppressive pathological graft-versus-host (GVH) symptoms are caused by T suppressor/killer (TS/K) cells of the donor which react towards allogeneic class-I-structures of the F1 recipient's major histocompatibility complex (MHC). The stimulatory pathological GVH symptoms, by contrast, are caused by donor T helper (TH) cells which react toward the recipient's allogeneic class-II-MHC structures. The possible implications of these observations for the pathogenesis of a number of GVH-like diseases in humans are discussed. The hypothesis is advanced that some of these GVH-like conditions, which arise either e causa ignota or after exposure to certain viruses or drugs, are caused by T lymphocytes reacting against self-MHC structures on lymphohemopoietic cells that were rendered "foreign". By analogy to GVHD, it is conceivable that the development of either stimulatory or suppressive GVH-like symptoms in individuals exposed to a given virus or sensitizing drug depends not on the etiologic agent per se, but on whether the predominant response is made by the individual's TH or TS@K cells. This, in turn, might depend on whether the agent becomes immunogenic in combination with class-II or class-I alloantigens.

Subsets of patients with aplastic anemia identified by flow microfluorometry

We used flow microfluorometry to analyze peripheral-blood mononuclear cells from 50 patients with aplastic anemia, to determine whether patients who would recover after immunosuppressive therapy could be distinguished before treatment from those who would not recover. Cells were labeled with murine monoclonal antibodies that are relatively specific for B cells, T cells, T-cell subsets, and monocytes. The data suggested that the number of lymphocytes and the ratios of various subclasses of T cells were not useful in identifying patients who were likely to recover. The complete absence of monocytes was found to identify patients who would not recover, but the presence of monocytes was also sometimes associated with lack of recovery. An unexpected finding was the significant (P less than 0.0001) association between clinical recovery and the presence of a population of small cells (4 to 8 micron) that were phenotypically associated with the erythroid lineage. If this association is confirmed, flow microfluorometry may be useful in selecting the optimal treatment for individual patients with aplastic anemia.

In vitro tests in severe aplastic anaemia (SAA): a prospective study in 46 patients treated with immunosuppression

Forty-six patients with severe aplastic anaemia (SAA) were studied for CFU-c growth on admission and 1 month post-treatment with immunosuppression (IS). Twenty-three patients became transfusion independent after IS, and were considered responders, and 23 did not. CFU-c growth from unfractionated bone marrow cells was comparable in both groups on admission and 1 month post-treatment. CFU-c growth from E rosette depleted BM cells (E-BM) was also comparable on admission. However, 1 month post-treatment, responders showed a significantly higher CFU-c growth (P = 0.02) from E-BM cells compared to non-responders. At the same time 7/8 responders studied showed T cell mediated suppression of autologous CFU-c growth. T cell depletion experiments do not give predictive information on the outcome of IS therapy on admission. They may, however, be helpful to identify responders early post-treatment.

Gold-induced bone marrow aplasia: successful treatment with antithymocyte globulin

A patient receiving gold treatment for rheumatoid arthritis developed sudden severe pancytopenia secondary to bone marrow aplasia. She required extensive hematological support but was unsuitable for bone marrow transplantation. Although early use of large doses of a chelating agent did not change the hematological parameters, subsequent use of antithymocyte globulin has been associated with substantial hematological improvement.

Cyclosporin A (CyA) does not enhance CFU-c growth in patients with severe aplastic anaemia

8 patients with severe aplastic anaemia (SAA) in remission following immunosuppressive therapy were studied for CFU-c growth from unfractionated or E-rosette depleted (E-) bone marrow (BM) cells. Cyclosporin A (CyA) was added to unfractionated BM cells at a concentration of 1000 ng/ml. The mean number of CFU-c/10(5) BM cells plated was 6 +/- 6 from unfractionated BM cells, 28 +/- 20 from E-BM cells, and 8 +/- 7 from unfractionated BM cells supplemented with CyA. All patients had significant increase of CFU-c growth after E rosette depletion (overall P = 0.002). On the contrary, only 1 patient showed an increase of CFU-c growth after addition of CyA, and overall there was no difference between untreated and CyA treated BM cells (P = 0.7). These results suggest that addition of CyA to BM cells in vitro is not an effective means of enhancing CFU-c growth in SAA patients.

Pure red cell aplasia and thymoma associated with high levels of the suppressor/cytotoxic T lymphocyte subset

A 64 year old man admitted to hospital with increasing effort dyspnoea and lethargy was found to have a thymoma and pure red cell aplasia. Lymphocytes accounted for 20-30% of marrow cells, and numbers of T8 suppressor/cytotoxic cells in peripheral blood were greatly increased. He remained anaemic after removal of the thymoma despite blood transfusions, and immunosuppression with prednisolone 60 mg and cyclophosphamide 50 mg daily was started. The dose of prednisolone was reduced to 15 mg owing to steroid myopathy and the risk of opportunistic infection. He went into remission, and the dose was further decreased to 10 mg daily.

High dose intravenous glucocorticoid in the treatment of childhood acquired aplastic anaemia

31 children with acute acquired aplastic anaemia were treated with very high doses of i.v. bolus methylprednisolone. In 3 of them, paroxysmal nocturnal haemoglobinuria was diagnosed. Therefore the responses of 28 patients have been evaluated. Normoblastaemia and reticulocytes were observed on about the 6th d and leucocyte and granulocyte response around the 11th d of treatment. The first haemoglobin (greater than or equal to 0.5 g/dl) and haematocrit elevations were documented on about the 16th d and the initial platelet response (average greater than or equal to 34 X 10(9)/l) took more than a month. At least 64% of the patients responded to this treatment including 2 cases in whom aplasia was observed following hepatitis. Although 10 episodes of recurrences occurred in 8 patients (with the exception of 3 patients' in whom 5 recurrences were observed), response to the same regimen was obtained. With 1 exception the side-effects of this treatment could be managed by decreasing the dose. With this treatment, acquired aplastic anaemia should no longer be considered a fatal disease, at least in children.

Reduced helper (OKT4+): suppressor (OKT8+) T ratios in aplastic anaemia: relation to immunosuppressive therapy

T cell subset composition of peripheral blood and bone marrow from 22 patients with aplastic anaemia (AA) was studied by monoclonal antibodies (OKT3, OKT4 and OKT8). In the peripheral blood, OKT3 (pan-T), OKT4 (helper/inducer-T) and OKT8 (suppressor-T) cells varied widely in number. The ratios of OKT4:OKT8 exhibited the same tendency. However, a subgroup of AA with a reduced ratio of lower than 1.0 was present both in cases with or without prior prednisolone therapy. Of the eight patients treated with immunosuppressants, four with reduced ratios responded, whereas the other four with normal or higher ratios did not. The ratios of two of four responders gradually reached the normal level. These results suggest that the reduced OKT4:OKT8 ratio may be related to the cell-mediated immunosuppressive mechanism postulated as a cause of stem cell inhibition in a subgroup of AA, and indicate prospectively the effectiveness of immunosuppressive therapy.

Bone marrow transplantation from identical twins in the treatment of aplastic anaemia: implication for the pathogenesis of the disease

Treatment of aplastic anaemia by bone marrow transplantation from a syngeneic (identical twin) donor has provided insights into the pathophysiology of the disease. We report from patients with severe anaemia who were treated by syngeneic bone marrow transplantation. None of the patients had sustained recovery of peripheral blood counts. All four received second transplants from the same twin donor after immunosuppressive conditioning treatment. Each had prompt recovery of haematopoiesis. A review of the literature indicates that failure of syngeneic bone marrow transplantation in patients with aplastic anaemia is not uncommon. These data indicate that aplastic anaemia may be caused by a mechanism other than an absence or intrinsic abnormality of haematopoietic stem cells in many patients.

CFU-C inhibitors in aplastic anaemia

Peripheral blood lymphocytes from 15 patients with marrow aplasia were tested for their ability to inhibit the proliferation of normal granulopoietic precursor cells (CFU-C) in agar culture, relative to the inhibitory effect of normal lymphocytes studied in parallel. Eight of the 15 patients with marrow aplasia had lymphocytes which were significantly less inhibitory to normal CFU-C than controls whereas 3 patients had lymphocytes which were significantly more inhibitory. Two further patients who had recovered from marrow aplasia were also studied. The effect of patient's plasma and normal plasma on normal CFU-C proliferation was also studied and in 1 case a potent inhibitor of granulopoiesis was demonstrated. In 9 cases CFU-C could be cultured from patient's marrow, and parallel studies examining the effects of lymphocytes or plasma on patient's CFU-C were performed in these. All 9 patients had low numbers of marrow CFU-C. In none of the 9 marrow samples tested was inhibition by patient lymphocytes significantly greater than normal controls. The results highlight the heterogeneity inherent in the study of aplastic states and serve to underline the importance of controls. In only a minority of cases (20%) was lymphocyte suppression of normal granulopoiesis by lymphocytes from patients with aplastic anaemia significantly greater than normal lymphocyte suppression.

T-lymphocyte--mediated granulopoietic failure. In vitro identification of prednisone-responsive patients

To identify patients with T-lymphocyte--mediated granulopoietic failure, we compared clonal growth of unfractionated bone-marrow cells with that of autologous marrow cells from which T lymphocytes had been removed, in a group of 234 patients. We also attempted to identify prednisone-responsive patients by culturing both unfractionated and T-depleted cells with and without glucocorticoids in vitro. Ninety-three patients were treated with prednisone for two to four weeks. Neutropenia resolved in 24 of 25 patients whose colony growth was enhanced by glucocorticoids in vitro, but in none of 68 whose cultures showed no response (P = 10(-10). Hemopoietic inhibitory T cells were found in 21 of the 24 prednisone-responsive patients. When these 21 patients were restudied during steroid treatment, the hemopoietic inhibitory cells were undetectable in steroid-responsive patients but were present in steroid-resistant patients. T lymphocytes can mediate granulopoietic failure in a variety of conditions, and in vitro studies identify most of the patients with these conditions. Hemopoietic inhibitory T cells are often steroid-sensitive, and in vitro study accurately predicts responses to steroid therapy.

Aplastic anemia during ethosuximide medication. Treatment with bolus-methylprednisolone

A girl, born in 1975, developed severe aplastic anemia in November 1982 while on ethosuximide monotherapy for petit mal epilepsy, about 3 months after starting the ethosuximide medication. She was treated with bolus-methylprednisolone as described by Bacigalupo et al. (13), transfusions and antibiotics. During the third week on this regimen slight improvements in granulocyte and reticulocyte counts were demonstrated, and after approximately 6 weeks she was in stable condition without further need of transfusions. Blood status should be checked regularly during ethosuximide therapy, particularly during the first 6 months.

Treatment of aplastic anaemia with antilymphocyte globulin (ALG)

Thirty-one patients with aplastic anaemia were treated with antilymphocyte globulin (ALG) followed by anabolic steroids. All patients were reviewed at least 1 year after receiving treatment. Twenty-one patients were considered to have a severe form of aplasia. ALG from three sources was used during the trial. Sixteen patients were alive at the time of analysis, eight who had had severe aplastic anaemia (38%) and five of these no longer require blood support. No difference in response was found according to type of ALG used. Patients with a long history of aplasia before treatment fared worse than those with a short history. These results were better than those obtained with anabolic steroids alone in historical controls. It is concluded that ALG treatment is worth giving to patients with aplastic anaemia but that the optimum way of giving this immunosuppression may be different from that used in this presentation.

Quantitative and qualitative analysis of stem cells of patients with aplastic anaemia

3 different methods, (1) assays of CFU-Cs and CFU-Es, (2) responsiveness of CFU-Cs and CFU-Es to low doses of CSF and ESF, respectively and (3) effects of ALG on CFU-C colony formation in vitro, were used to evaluate the quantitative and qualitative defects of stem cells in 28 patients with aplastic anaemia. Some patients with aplastic anaemia who had attained complete remission several years previously, exhibited severely depressed in vitro CFU-C colony formation. This suggests that the defect persists for a long time after clinical complete remission. Residual marrow CFU-Cs and CFU-Es did not have defective responses to the humoral stimulating factors, CSF and ESF. No patient showed a rise of colony number after treatment with ALG in vitro.

Dexamethasone enhances 'CSA' release and depresses 'BPA' release

Dexamethasone 10(-7) M enhanced the release of granulocyte-macrophage colony stimulating activity (GM-CSA) by peripheral blood cells from 15 normals. In 16 patients with hypoplastic marrow failure this effect was more prominent, the release of GM-CSA being increased up to 10-fold by dexamethasone. Dose-response curves of patient cell supernatants indicate that dexamethasone acts by abrogation of an inhibitor on CSA-production. Dexamethasone decreased the release of burst promoting activity (BPA) in all normals and most patients. We conclude that the interaction of glucocorticoid hormones with lymphocyte function results in positive and negative effects on haemopoiesis in vitro. Preliminary experiments in one patient suggest that the steroid effect in vivo correlates with GM-CSA enhancement in vitro.

Antithymocyte globulin treatment in patients with aplastic anemia: a prospective randomized trial

We evaluated the efficacy of antithymocyte globulin for the treatment of moderate to severe aplastic anemia in a randomized controlled study. Eleven of 21 patients initially randomized to receive antithymocyte globulin (given intravenously on eight consecutive days) had sustained improvement in hematopoiesis within three months of treatment; none of 21 control patients who received supportive care alone improved (P = 0.0005). Six of 12 control patients who subsequently received antithymocyte globulin improved. Responders had gradual improvement in hematopoiesis, but none recovered completely normal peripheral-blood counts. The severity of bone-marrow failure, age, cause of aplastic anemia, and transfusion history had no apparent bearing on treatment outcome. The interval from diagnosis to antithymocyte globulin treatment correlated inversely with the chance of a treatment response, although this correlation was not statistically significant. These data indicate that antithymocyte globulin is effective in improving hematopoiesis in some patients with aplastic anemia.

Generation of CFU-C suppressor T cells in vitro. V. A multistep process

Different cell fractions obtained from five patients with immune severe aplastic anaemia (SAA) in complete autologous haematologic reconstitution were tested for CFT-c suppression. Bone marrow mononuclear cells (BMMC), but not peripheral blood mononuclear cells (PBMC), showed definite CFU-c inhibitory activity. On the contrary, both peripheral blood and marrow E rosetting cells (E+) suppressed CFU-c growth. The suppressor activity of PBE+ cells could not be rescued by adding back PBE- cells and/or PB adherent cells (AC). In addition, unfractionated PBMC exposed to sheep red blood cells (SRBC) suppressed CFU-c growth. PBMC from normal donors exposed to SRBC had no suppressor activity. This study suggests that CFU-c suppressor T cells in the peripheral blood of SAA patients are in different activation state as compared to BM cells from the same patients, and also differ from normal PB cells. The identification of T cells with different requirements for in vitro activation in order to exhibit a suppressor activity, suggests that generation of suppressor cells is a multistep process, and this may have practical implications for in vitro assays designed to test for immune suppression of haematopoiesis.

Bone-marrow transplantation for severe aplastic anaemia using histocompatible unrelated volunteer donors

Two patients with severe aplastic anaemia received bone-marrow transplants from unrelated donors selected for HLA compatibility. Graft-versus-host disease occurred in both patients but responded to treatment. Both patients had stormy courses after grafting, but subsequently their conditions improved, and one was not receiving any treatment at follow-up after day 330 while the other had mild chronic graft-versus-host disease at day 150. These results show that unrelated, histocompatible volunteers may successfully donate marrow for the treatment of severe aplastic anaemia, though many problems remain to be solved.

GM-CFC growth in chronic granulocytic leukaemia is not affected by a soluble inhibitor released by aplastic anaemia T-cells or mitogen-primed normal T-lymphocytes

Peripheral blood (PB) and bone marrow (BM) cells were obtained from 12 patients with chronic granulocytic leukaemia (CGL) and cultured in agar for granulocyte macrophage colony formation (GM-CFC). In addition PB and BM CGL cells were co-cultured with T-lymphocytes from patients with immune severe aplastic anaemia (SAA), or with T-cells from healthy donors primed with pokeweed mitogen (PWM). The supernatants of SAA and PWM primed T-cells were also added to CGL cells grown in agar. Normal marrow cells obtained from eight healthy donors were used to set up control cultures and co-cultures. The results of this study indicate that, firstly, T-cells derived from SAA patients and their supernatants suppress GM-CFC growth of normal marrow cells but not of PB nor BM CGL cells, and, secondly, normal T-cells primed with PWM and their supernatants suppress normal marrow GM-CFC but not colony formation of BM nor PB CGL cells. These results provide further evidence that mediators which are effective in regulating normal myeloid progenitor cells fail to inhibit the in vitro growth of GM-CFC from CGL patients.