Aplastic anemia (first of two parts): pathogenesis, diagnosis, treatment, and prognosis

Regulation of hematopoiesis by T lymphocytes and natural killer cells

T lymphocytes and natural killer (NK) cells exert both stimulatory and suppressive effects that regulate growth and differentiation of hematopoietic cells. Activated T and NK cells have been demonstrated in different pathological states of bone marrow failure and are proposed to play a role in the pathogenesis of the disease. T and NK cells have also been shown to be responsible for bone marrow graft rejection in both allogeneic and syngeneic donor/recipient combinations. Lymphocytes can regulate hematopoietic cell growth by direct cellular contact or by releasing soluble factors, such as colony-stimulating factors, immune interferon, lymphotoxin, and tumor necrosis factor, active on hematopoietic precursor cells.

Acquired aplastic anaemia: a PNH-like disease?

Bone marrow from 20 patients with aplastic anaemia at different stages of disease and from three patients with paroxysmal nocturnal haemoglobinuria (PNH) was incubated in isosmolar sucrose with 5% autologous serum prior to culture in methylcellulose. If fresh serum was used, colony formation by granulocyte-macrophage colony forming cells (GM-CFC) and immature erythroid precursors (BFU-E) was reduced to approximately 50% in all patients tested, at any stage of disease, including complete autologous bone marrow recovery. Heat inactivation and complement inactivation with EDTA completely abrogated this inhibitory serum effect. Selective inactivation of the classical, antibody dependent complement pathway with Mg2+ EGTA reduced the inhibitory effect by 50%. Complement sensitivity of haemopoietic precursors is a known feature of PNH. Since the majority of our patients did not have PNH as judged by a negative sucrose-test on mature erythrocytes, we conclude that, in aplastic anaemia, haemopoietic cells express a PNH-like defect at a primitive level.

Treatment of acquired amegakaryocytic thrombocytopenic purpura with cyclophosphamide

A patient with severe amegakaryocytic thrombocytopenic purpura was treated with cyclophosphamide and had an excellent response after four weeks. His condition remained in complete remission for at least five months. Acquired amegakaryocytic thrombocytopenic purpura is a rare disorder with several possible causes. An intrinsic defect at the level of the megakaryocyte colony-forming units, or a circulating autoantibody directed against these colony-forming units has been suggested. This patient's response to cyclophosphamide supports the hypothesis of an immune mechanism in some of these cases, and it is recommended that immunosuppressive therapy be further evaluated.

Hemopoietic marrow function in chronic neutropenia of blacks: cure of aplastic anemia by allogeneic marrow transplantation from a neutropenic sibling donor

A black patient with severe aplastic anemia is described who underwent successful bone marrow transplantation from a sibling with chronic neutropenia. During an evaluation to identify a suitable donor, it was found that the majority of family members tested had neutropenia, with no familial history of significant infections or related hospitalizations. In vitro hemopoietic culture studies of marrow from the patient's HLA-MLC-matched siblings showed normal numbers of pluripotential and committed hemopoietic progenitors; in vitro hemopoietic colony formation from the patient was markedly subnormal, consistent with the clinical picture of severe aplastic anemia. Following appropriate conditioning therapy, marrow transplanted from one of these neutropenic sibs produced full hematopoietic reconstitution. Posttransplant marrow culture studies of the patient showed restoration of a normal pattern of in vitro hemopoiesis. The in vitro culture studies and clinical experience in this patient support the concept that chronic neutropenia of blacks is not primarily a marrow progenitor cell disorder but, more likely, a manifestation of a genetically determined alteration in granulocyte kinetics.

The effect of T cells from patients with infectious mononucleosis on CFU-CGM proliferation: a preliminary report

The neutropenia occurring during infection is a poorly understood phenomenon. Immunologically-stimulated T lymphocytes, acting upon normal bone marrow stem cells, have been etiologically implicated in several disorders. Fifteen patients, ages 17 to 25 years, and diagnosed with infectious mononucleosis by positive heterophile titers, were studied. Peripheral blood T lymphocytes were separated using sheep red blood cell rosetting. They were then cocultured with normal bone marrow cells, in a concentration of 2 X 10(4) cells/ml, in methylcellulose containing 10% colony-stimulating activity. Normal BM was obtained from patients with nonmalignant hematologic disorders, or leukemia in remission. Bone marrow cells were cultured at a concentration of 1 X 10(5) or 5 X 10(5) cells/ml, alone (control) or with T lymphocytes. Plates were incubated at 37 degrees C with 5% CO2. Colonies were scored at 14 days. Inhibition of normal, bone marrow growth was observed at both concentrations, after addition of T lymphocytes to the culture system. Such suppression was significant (p less than 0.05) for the lower concentration of normal bone marrow cells only. Variable and partial abrogation of effect was seen after overnight incubation of T lymphocytes, possibly due to loss of suppressor activity. There were insufficient numbers of tests with supernatant to allow computation of statistical significance. Correlation between T-cell ratios and suppressive effect has not been determined, although it is suspected that the responsible cells are within the T-suppressor fraction.

The release of interleukin-2 (IL-2) and colony stimulating activity (CSA) in aplastic anemia patients: opposite behaviour with improvement of bone marrow function

Peripheral blood cells from patients with aplastic anemia were tested for their ability to release interleukin-2 (IL-2) and colony stimulating activity (CSA) before treatment. IL-2 release--as measured in the mouse thymocyte assay--was abnormally high in 18/34, and abnormally low in 10/34 patients. "Low" release was due to simultaneous release of thymocyte inhibitors. In 18 patients who achieved self-sustaining hemopoiesis after high dose immunosuppressive therapy, excess IL-2 release decreased to low levels (p less than 0.001), and the release of inhibitors disappeared. In contrast, the release of CSA by patient cells--which did not correlate with peripheral blood monocyte counts--either remained high or increased to excessively high values in 24/24 patients tested before and after successful immunosuppressive treatment. Patients with stable hemopoietic grafts after bone marrow transplantation for aplastic anemia, did not release excess CSA. It is concluded that IL-2 and CSA play opposite roles in aplastic anemia. High IL-2 release seems associated with disease activity, whereas high CSA-release appears to reflect a repair mechanism.

Immunological abnormalities in a child with constitutional aplastic anemia

This case report describes a child with severe constitutional hypoplastic anemia and Seckel's syndrome. Immunological analysis on mononuclear peripheral blood cells revealed an abnormally low ratio of T-helper to T-suppressor/cytotoxic cells and a highly increased number of HLA-DR-positive T suppressor/cytotoxic cells. Interferon-gamma and interleukin-2 production by mitogen-stimulated peripheral blood mononuclear cells was slightly reduced, and no spontaneous production of these lymphokines was seen. The immunological abnormalities demonstrated in this case of constitutional aplastic anemia may indicate common features with acquired aplastic anemia.

Drug-induced aplastic anaemia and agranulocytosis. Incidence and mechanisms

Aplastic anaemia and agranulocytosis are uncommon but serious adverse effects of drug therapy. They result from an adverse interaction between the drug and the haemopoietic pathway in certain susceptible individuals. The nature of this idiosyncratic interaction differs for different drugs and possibly for different individuals. In some instances an immune mechanism might be implicated, in others the patient's cells might carry a genetic susceptibility to the drug, while yet other patients might metabolise the drug abnormally. The idiosyncratic nature of these effects has made their investigation difficult, but experimental studies have allowed some progress in our understanding. In a practical sense, however, responsibility for preventing these problems will remain with clinicians, who should be alert to the risks and revise their prescribing habits accordingly.

Hypocellular bone marrow with increased blasts

Twenty patients with hypocellular bone marrow and increased blasts (HBMIB) were reviewed. The median age was 60 years with a male:female ratio of 17:3. History of alcohol abuse was noted in 30%, potential exposure to toxic chemicals in 20%, second malignancies in 20%, and aplastic anemia in 25%. Pancytopenia with marrow hypocellularity and increased marrow blast cells were characteristic hematopathologic features. Marrow hypocellularity was moderate to severe (less than or equal to 25%) in over half of the cases and mild to moderate (greater than 25, less than or equal to 35%) in the remainder. Blast cells were the predominant cellular elements in the marrow displaying scanty to moderate amounts of cytoplasm, round to oval nuclei, and one or more nucleoli. Special stains were performed in 19 cases. Blast cells morphologically displayed myeloid features, but Sudan black B and/or peroxidase positivity was noted in only ten patients. The overall mortality was high, especially in patients undergoing chemotherapy. At 1 year follow-up, 11 patients had received chemotherapy and eight of these eleven were dead compared to three of nine patients dead in those not receiving chemotherapy. Only two patients developed "overt" leukemia evidenced by hypercellular marrow and over 30% blast cells in the peripheral blood. HBMIB is a distinct clinicopathologic entity characterized by severe marrow failure and a low response rate to chemotherapy.

Myelopoiesis and marrow adherent cells in estradiol-treated mice

Myelopoiesis and marrow adherent cells were evaluated in C57Bl/6J mice at two and four weeks after treatment with 0.1 mg 17 beta-estradiol cyclopentylpropionate. Estradiol-treated mice were lymphopenic and eosinopenic at two and four weeks; in addition, neutropenia occurred at four weeks. Numbers of lymphoid, granulocytic, and erythroid cells were decreased in the marrow at two and four weeks. The numbers of granulocyte-macrophage and fibroblast colony-forming units in the humeral marrow were also decreased at two and four weeks. However, the hematopoietic ability of marrow adherent cells was unchanged in estradiol-treated mice. Thymic cortical atrophy, metaphyseal osteosclerosis, and neutrophilic infiltration of the uterus occurred in estradiol-treated mice.

Differentiation of normal marrow and HL60 cells induced by antithymocyte globulin

Antithymocyte globulin (ATG) therapy is an important treatment alternative for patients with acquired aplastic anemia. The mechanism by which it exerts its effects on hematopoiesis is unknown. In this report, we describe the ability of horse ATG to induce growth and differentiation of normal bone marrow. A single cell suspension of normal human bone marrow was cultured in methylcellulose medium and examined for the growth and maturation after incubation with ATG (10 micrograms/ml). After 3-4 days of culture, spherical colonies containing mature myeloid elements were found in cultures containing ATG but not in cultures containing medium or preimmunization horse IgG. The addition of 10% colony-stimulating factor increased growth by 40%. The number of spherical colonies is not dependent on the presence of macrophages or T lymphocytes. This property of ATG may be relevant to the mechanism behind the hematologic recovery in some patients with acquired aplastic anemia. We also describe the ability of ATG to induce terminal differentiation in the HL60 leukemic cell line. ATG binds to HL60 cells and at concentrations between 10 and 100 micrograms/ml, 50% of the cells become mature granulocytes, acquire the ability to reduce nitroblue tetrazolium, and lose their proliferative capacity in the clonogenic assay. These new observations of ATG-induced differentiation of normal marrow myeloid elements and terminal differentiation of the HL60 cell line point to different avenues for future search of differentiation-inducing agents.

Predictive factors for response to anti-thymocyte globulin in acquired aplastic anemia

Lymphocyte phenotype, bone marrow cellularity, in vitro marrow growth potential, and treatment responses were examined in 22 patients with acquired aplastic anemia who were given anti-thymocyte globulin. Eleven of 22 patients (50 percent) had a significant hematologic response within three months of therapy, confirming the effectiveness of this therapy. Pretreatment fetal hemoglobin concentration, age, sex, severity of pancytopenia, degree of maximal lymphopenia, and total hemolytic complement consumption did not affect response. Patients with severe disease who were treated within 16 weeks after diagnosis had a higher response rate (55 percent) than those treated after 16 weeks (20 percent). In patients with severe disease, a higher pretherapy bone marrow cellularity (p less than 0.001) and presence of granulocyte-macrophage colony growth correlated with response. The actuarial survival of patients with response in the group with severe disease was 100 percent at 12 months as compared with 33 percent in patients without response. Following anti-thymocyte globulin therapy, a reduced number of blood lymphocyte T subpopulations was seen in all patients. At three months after therapy, the patients with response who had severe disease had increased T8-positive cells (+56 percent versus -4 percent for patients without response) and la-positive cells (+32 percent versus -62 percent).

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.

Thrombopoiesis and thrombokinetics--an approach to the evaluation of thrombocytopenia

Thrombocytopenia is a common clinical disorder with a diverse group of etiologies. Traditionally, the approach to identifying the mechanism of thrombocytopenia has been empirical, primarily due to a lack of clear understanding of normal thrombopoiesis and its control. Additionally, readily available clinical measurements that reflect patterns of altered thrombopoiesis are unavailable. Recent experimental and clinical observations permit us to approach this disorder from a kinetic point of view to classify thrombocytopenia by four mechanistic categories: peripheral destruction and consumption, hypoproliferative thrombocytopenia, ineffective thrombopoiesis, and distributional causes. The application of the measurement of mean platelet size, in conjunction with a bone marrow examination, allows the clinician to more readily identify the cause of a low platelet count in a less empirical manner.

Idiopathic Aplastic Anemia in a Dog

A case of idiopathic aplastic anemia in a dog was characterized by pancytopenia and bone marrow aplasia. Erythroid colony-forming units (CFU-E) were not detected in bone marrow culture. Addition of the dog's serum to CFU-E culture from control dogs failed to suppress colony formation, suggesting that humorally-mediated suppression at the CFU-E level was not a cause of the aplastic anemia.

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.

Bone marrow transplantation

Bone marrow transplantation is increasingly used to treat a broad spectrum of human diseases including aplastic anemia, leukemia, solid tumors, immune and genetic disorders. In certain circumstances the role of transplantation is reasonably well established, such as aplastic anemia and resistant leukemia. In other circumstances there is controversey as to the role of transplantation such as leukemia in remission. An increasing number of genetic disorders including severe combined immunodeficiency, Wiskott-Aldrich syndrome, osteopetrosis, and Thalassemia have been cured by transplantation. Despite substantial progress, with transplantation that remain to be solved including graft-vs.-host disease, interstitial pneumonia, immune deficiency, and the lack of suitable donors for most potential recipients. These problems and potential approaches are discussed in detail Future direction of research include the application of transplantation to other diseases as well as the use of this approach either as a prelude to solid-organ grafts or as a vehicle for the introduction of new genetic information.

Current considerations of the etiology of aplastic anemia

Aplastic anemia is a disorder characterized by marrow aplasia and pancytopenia. The pathogenetic mechanisms that lead to bone marrow aplasia have been intensively studied. Data obtained from these studies suggest that aplastic anemia is a heterogeneous disorder with regards to pathogenesis. Bone marrow aplasia may result from a number of abnormalities including qualitative or quantitative abnormalities of hematopoietic stem cells, abnormal interaction between bone marrow accessory cells (lymphocytes and macrophages) and hematopoietic stem cells, cytotoxic humoral inhibitors of hematopoiesis, and abnormalities of the bone marrow microenvironment. A number of new therapeutic options have improved the survival of patients with aplastic anemia. Allogeneic bone marrow transplantation has actually resulted in the cure of patients. Unfortunately, only a minority of patients have a suitable bone marrow donor and alternate modes of therapy have been sought. Encouraging results have been reported from several centers concerning the use of antilymphocyte serum in patients with aplastic anemia. Certainty of the ultimate long-term benefit of this type of immunosuppressive therapy is not possible until careful, randomized, prospective studies of its use are completed.

Comparison between bone marrow transplantation and antithymocyte globulin in treatment of young patients with severe aplastic anemia

Fifty-seven patients younger than 25 years with severe aplastic anemia underwent either bone marrow transplantation or antithymocyte globulin therapy (ATG) to ascertain which approach should be used in young patients. Thirty-five patients who had an HLA-identical sibling donor underwent bone marrow transplantation after conditioning with cyclophosphamide and low-dose total-body radiation. Twenty-two patients who did not have an HLA-identical donor received ATG. The 2-year actuarial survival of patients after transplant is 72% (95%, CI 64% to 80%), versus 45% (95%, CI 29% to 61%) in those given ATG therapy (P = 0.18). In those patients surviving 6 months after treatment, return of peripheral blood counts to normal values was more common in patients who received marrow transplant compared with those given ATG therapy (P less than 0.001). Furthermore, 24 of 26 transplant survivors had Karnofsky performance scores greater than 90%, compared with only five of 13 ATG survivors. These data suggest that bone marrow transplantation is the preferred therapy for severe aplastic anemia in young patients who have an HLA-identical sibling donor. ATG should be reversed for those young patients with severe aplastic anemia who do not have a histocompatible marrow donor.

Marrow transplantation in hepatitis-associated aplastic anemia

Seventeen patients who developed aplastic anemia in association with viral hepatitis were transplanted with sibling marrow. Of the 16 HLA-identical recipients, 14 were conditioned with cyclophosphamide, 200 mg/kg, and two received 10 Gy total body irradiation. One HLA-nonidentical recipient received 123 mg/kg cyclophosphamide and 10 Gy total body irradiation. Of the 14 patients conditioned with cyclophosphamide alone, one died on day 49 after graft rejection, and 13 had sustained engraftment. Six of the 13 developed acute graft-versus-host disease (GVHD), which led to death from opportunistic infections 84, 97, and 130 days after transplantation in three patients. Four of the 13 developed chronic GVHD, two without preceding acute GVHD. Currently, ten of the 14 cyclophosphamide-conditioned patients are alive 0.9-12.4 (median 5.9) years from transplantation. The two HLA-identical recipients conditioned for grafting with total body irradiation died after failure of engraftment, and one also developed concomitant hepatic venocclusive disease. The mismatched recipient conditioned with radiation and cyclophosphamide died of severe GVHD 18 days posttransplant. We conclude that survival, graft rejection, and incidence of acute and chronic GVHD after marrow transplantation for hepatitis-associated aplastic anemia are similar to those of patients transplanted for aplastic anemia of other etiologies. Previous hepatic damage from viral hepatitis and liver function abnormalities existing at the time of grafting do not appear to increase the risk of posttransplant morbidity and mortality from hepatocellular damage or venocclusive disease in cyclophosphamide-conditioned patients.

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.

Aplastic anemia complicating systemic lupus erythematosus: response to androgens in two patients

We describe two female patients with systemic lupus erythematosus (SLE) who developed severe aplastic anemia. Although each patient had received multiple medications including diphenylhydantoin, the relationship to these drugs to the development of marrow aplasia was unclear. After administration of an oral androgen (oxymethalone) and corticosteroids, there was complete hematologic recovery. Both patients relapsed when oxymethalone was withdrawn, and both recovered when androgen therapy was reinstituted, with or without high-dose prednisone. In both patients, there was complete reversal of pancytopenia despite the presence of initially severe marrow aplasia (less than 10% cellularity). However, in both cases, prolonged androgen therapy (2 months) was required before hematologic improvement occurred. Androgens are known to stimulate hematopoiesis in man, and they appear to influence immune function in a mouse model of SLE. Thus androgens may be particularly useful in the treatment of SLE-associated aplastic anemia.

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.

Bone marrow cell dose and kinetics of recovery following allogeneic marrow transplantation in man

In 50 patients transplanted for acute or chronic leukemia we studied the correlation between the number of infused bone marrow cells/kg recipient body weight and the time needed for engraftment. Engraftment was arbitrarily defined as the first day of 1 X 10(9) leukocytes/l and of 20 X 10(9) reticulocytes/l after the posttransplantation nadir. There is a negative non-linear correlation between the duration of leukopenia following marrow transplantation and the amount of transfused nucleated cells (p = 0.01). Since the incidence of infectious or hemorrhagic complications depends directly on the duration of aplasia it is justifiable to give a maximal cell dose.

Improved survival following bone marrow transplantation for aplastic anaemia

We transplanted 46 patients with severe aplastic anaemia with a new pretransplant immunosuppressive regimen consisting of cyclophosphamide (200 mg/kg) and low-dose total body irradiation (3 Gy). This regimen (CY-TBI-2) was designed to decrease the high risk of graft rejection associated with the use of cyclophosphamide alone, without increasing the incidence of graft-versus-host disease (GHVD) or interstitial pneumonia (IPn). Two-year actuarial disease-free survival of patients conditioned with CY-TBI-2 was 62% (95% CI: 47-77%). Only one patient rejected her graft and the incidence and severity of GVHD and IPn were not increased compared to previous studies. Patients less than 25 years of age had excellent 2-year survival of 82% (95% CI: 69-95%). These data indicate that CY-TBI-2 is an effective means of preventing graft-rejection and achieving long-term disease-free survival in multiply transfused patients with severe aplastic anaemia.

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.

Allogeneic bone marrow transplantation

Allogeneic bone marrow transplantation now has an established place in the treatment of severe aplastic anemia and acute leukemia. Major problems to be overcome in transplantation in patients with aplastic anemia are marrow graft rejection and graft vs. host disease. Results are better in younger patients and in patients who have not been previously transfused. Newer approaches to the control of graft vs. host disease, for example total lymphoid irradiation and the immunosuppressive agent, cyclosporin A, hold promise for future progress. In patients with acute leukemia, the major clinical problems are early infections, recurrent leukemia, graft vs. host disease, and interstitial pneumonia. Both ultra-isolation and prophylactic granulocyte transfusions are able to decrease the incidence of early infections. Attempts to intensify the conditioning regimen have failed to decrease the incidence of recurrent leukemia, but transplantation earlier in the course of disease, particularly in patients with acute, nonlymphoblastic leukemia in first remission, have decreased the incidence of recurrent leukemia. Both acute and chronic forms of graft vs. host disease have been recognized. Acute graft vs. host disease continues to be a significant clinical problem, in spite of the use of Cyclosporin A. Chronic graft vs. host disease is being recognized earlier and treated successfully with immunosuppressive agents. Interstitial pneumonia, primarily secondary to cytomegalovirus, remains the major cause of death post-transplantation. In spite of these problems, however, patients with acute non-lymphoblastic leukemia in first remission have a 60% likelihood of remaining alive, free of disease following allogeneic marrow transplantation from an HLA identical sibling. Patients with acute leukemia who have relapsed who undergo allogeneic marrow transplantation have a longer survival than patients treated with conventional chemotherapy and even patients in relapse have a significant likelihood of cure following high-dose chemoradiotherapy and allogeneic marrow transplantation.