Haematopoietic suppressing activity of gamma-interferon in serum and bone marrow of aplastic anaemia patients

To determine the mechanism by which haematopoiesis is suppressed in aplastic anaemia, the effect of the sera from 6 patients on the granulopoietic precursors (colony-forming units in culture; CFU-C) was studied in vitro. Addition of the sera from 2 patients significantly suppressed CFU-C. The suppressive effect of the sera on CFU-C was inhibited by the addition of 1.5 NU/ml of anti-gamma-IFN antibody. In another patient, anti-gamma-IFN antibody increased autologous CFU-C although the serum of the patient did not suppress CFU-C. Serum gamma-IFN levels of all patients were under 2 IU/ml. The above findings suggest that humoral factors inhibit haematopoiesis in some patients with aplastic anaemia, and that gamma-IFN plays a role as an inhibitor even at a low concentration.

Effects of thrombocytopoiesis-stimulating factor on terminal cytoplasmic maturation of human megakaryocytes

Aplastic anemia serum (AAS) contains humoral factors that alter both proliferation and maturation of human megakaryocytes (MK). The ability of AAS to augment MK colony formation (colony-forming unit, CFU-MK) was neutralized by an antiserum against MK colony-stimulating factor (MK-CSF), a glycoprotein isolated from AAS. The adsorbed AAS still retained the ability to accelerate cytoplasmic maturation of recognizable MK. Similar experiments were done with thrombocytopoiesis-stimulating factor (TSF) and an anti-TSF antiserum to further define the activity in AAS responsible for accelerating cytoplasmic maturation. Bone marrow fractions enriched for recognizable human MK, but devoid of CFU-MK, were obtained by centrifugal elutriation and placed in short-term liquid cultures. MK progressed through identifiable maturation stages (1-4) more quickly in the presence of either TSF or AAS. TSF slightly enhanced the cloning efficiencies of CFU-MK, but did not alter the number of MK in individual colonies derived from non-adherent, low-density, T-cell-depleted bone marrow. In contrast, granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 3 (IL-3), and crude AAS substantially augmented both MK colony formation and cells per colony. TSF also doubled the percent 35S incorporation into platelets of immunothrombocythemic mice, but stimulation was completely abolished by anti-TSF. Anti-TSF antiserum was then used to analyze the promotion of MK colony formation by cytokines. Cloning efficiencies of CFU-MK were reduced to baseline values when TSF was pretreated with anti-TSF; however, the MK colony-stimulating activity (MK-CSA) of GM-CSF, IL-3, or AAS was not altered by adsorption with anti-TSF. In contrast, the cytoplasmic maturation of recognizable MK was slower, and fewer mature stage-4 cells were present at days 1-3 in AAS adsorbed with anti-TSF than MK cultured in AAS treated with normal rabbit serum or untreated AAS. Therefore, TSF appears to be a major factor in AAS that accelerates terminal maturation of human MK. TSF primarily affects megakaryocytopoiesis by promoting MK maturation rather than enhancing CFU-MK proliferation.

Aplastic anemia in Taiwan and its etiological factors

Ninety patients with a strict diagnosis of aplastic anemia were observed during a 4-year period. The incidence of aplastic anemia is estimated to be much higher here than in western countries. A disproportionately large number of young males were noted among our patients. Two cases were congenital. One case presented a past history of paroxysmal nocturnal hemoglobinuria. The etiology of 8 cases (8.9%) could be attributed to drugs and/or chemicals. In the remaining 79 cases (87.8%), the causes of the disease were unknown. The carrier rate of the hepatitis B surface antigen in the patients with aplastic anemia was similar to that of the general population, and chronic hepatitis B infection was not considered a major etiological factor. Coexistence of abnormal liver functions at the initial presentation was noted in 21.9% of the patients. Exposure to unknown drugs by self-medication was possibly one of the major causes of the high incidence of aplastic anemia and the associated abnormal liver functions in our patients.

[Abnormalities in the regulation of erythropoiesis by bone marrow fibroblasts in aplastic anemia]

The influence of bone marrow fibroblasts in healthy subjects and patients with aplastic anemia on normal erythroid colony formation was studied using the methylcellulose method. These fibroblasts were treated with methylprednisolone as well. Bone marrow fibroblasts of healthy subjects and patients with aplastic anemia, and the supernatant of their conditioned medium significantly inhibited normal erythroid colony formation. A significantly marked inhibition of normal erythroid colony formation was observed of bone marrow fibroblasts (or the conditioned medium) of the aplastic anemia, when compared with that of the bone marrow of healthy subject fibroblasts (or the conditioned medium). By treating both groups of the bone marrow fibroblasts with methylprednisolone the inhibition was slightly improved. From the above experimental results, it was suggested that the bone marrow fibroblasts and the conditioned medium inhibited normal erythroid colony formation through humoral factors secreted by the fibroblasts, and through contact between the fibroblasts and erythroid colony formation cells.

Lung function in allogeneic bone marrow transplantation recipients

In order to investigate the incidence of pulmonary function complications following bone marrow transplantation (BMT), 17 patients with leukaemia and 8 with aplastic anaemia were sequentially assessed over a one year period. Before BMT, all the patients were free of respiratory symptoms and had both normal chest X-ray and routine lung function tests. However, 5 patients disclosed airway hyperreactivity. Aplastic anaemia patients had significantly lower haemoglobin-adjusted diffusing capacity for carbon monoxide (DLCO) than those with leukaemia, a finding significantly related to the lower haemoglobin values shown in the former individuals. Following BMT there were transient mild to moderate reductions in DLCO and static lung volumes; moreover, patients with leukaemia had lower DLCO than those with aplastic anaemia. Fourteen of the 25 patients had ventilatory defects, including 10 individuals with bronchial hyperresponsiveness. Post-BMT lung function changes were transiently accompanied by mild to moderate symptoms of respiratory disease in most of the patients.

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.

Renal lesions and clinical findings in thalassemia major and other chronic anemias with hemosiderosis

Renal lesions found in 21 autopsied patients with hemosiderosis, 18 with beta-thalassemia, two with Blackfan-Diamond anemia, and one with aplastic anemia included: cellular glomeruli with increased mesangial matrix; hemosiderin deposit in visceral and parietal glomerular epithelial cells; greater hemosiderin deposit in terminal straight portions of proximal convoluted tubules and distal convoluted tubules than in connecting segments, or collecting tubules, connective tissue ferrugination; lipofuscin in tubular epithelium and vascular smooth muscle; infrequently, intimal or medial arterial thickening, and, in one patient with thalassemia, an infarct resulting from arterial thrombus. The progression of these lesions over the course of disease, and possible effects on the various lesions of high transfusion regimen, oral pancreatin, vitamin E supplementation, or treatment with intramuscular, subcutaneous, or intravenous desferrioxamine were evaluated. The results of urine and renal function studies of 4 of the autopsied patients (3 thalassemia, 1 Blackfan-Diamond anemia), and 14 patients with thalassemia and 4 with Blackfan-Diamond anemia who were not autopsied, are presented. Rarely significant until preterminal stages, the renal functional changes reflect distal more than proximal tubule dysfunction.

Stimulation of myelopoiesis in patients with aplastic anemia by recombinant human granulocyte-macrophage colony-stimulating factor

Aplastic anemia is a syndrome in which pancytopenia occurs in the presence of hypocellularity of the bone marrow. To assess the biologic activities of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) in aplastic anemia, we gave GM-CSF (60 to 500 micrograms per square meter of body-surface area) to 10 patients with moderate or severe disease, by continuous intravenous infusion daily for two weeks, and repeated the treatment after a two-week rest period. The treatment increased the white-cell count (1.6- to 10-fold) in all patients, primarily because of an increase in the numbers of neutrophils (1.5 to 20-fold), eosinophils (12- to greater than 70-fold), and monocytes (2- to 32-fold). Rates of hydrogen peroxide production in purified granulocyte fractions increased during GM-CSF treatment. Increases in bone marrow cellularity, myeloid precursor cells, and myeloid:erythroid cell ratios accompanied the white-cell response. Despite the in vivo response of the white-cells, the concentration of colony-forming cells remained the same. Measurable concentrations of interleukin-2 (2 to 15 units per milliliter) were found in the serum of 8 patients, and high levels of erythropoietin (81 to 1200 IU per liter) were found in 10 patients. The predominant side effects were constitutional symptoms. These results indicate that recombinant human GM-CSF is effective in stimulating myelopoiesis in patients with severe aplastic anemia and may benefit some patients in whom the disorder is refractory to standard forms of therapy.

Ovarian function following marrow transplantation for aplastic anemia or leukemia

One hundred eighty-seven women between 13 and 49 years of age had ovarian function evaluated from 1 to 15 years (median, 4) after marrow transplant for aplastic anemia or leukemia. Among 43 women transplanted for aplastic anemia following 200 mg/kg cyclophosphamide (CY), all 27 less than 26 years of age, but only five of 16 greater than 26 years of age recovered normal ovarian function. Nine of the 43 have had 12 pregnancies, resulting in eight live births, and two elective and two spontaneous abortions. All eight children are normal. Nine of 144 women transplanted for leukemia following 120 mg/kg CY and 9.20 to 15.75 Gy total body irradiation (TBI) recovered ovarian function. Two of these nine have had three pregnancies, resulting in two spontaneous and one elective abortion. The probability of having ovarian failure was 0.35 by 7 years for patients receiving CY alone and was 1.00 at 1 year for patients receiving CY plus TBI (P less than .0001). By 7 years after transplant the probabilities of having normal ovarian function were 0.92 after CY alone and 0.24 after CY plus TBI (P less than .0001). Multivariate analysis showed that TBI was the only factor significantly influencing ovarian failure and that both TBI and greater patient age at transplant were significantly associated with a decreased probability of recovering normal ovarian function. These data demonstrate that after high-dose CY, recovery of ovarian function occurs in younger women and in a minority of older women, but after CY and TBI, recovery occurs in only a few younger women and none of the older women.

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.

Human T cell leukemia virus-I-associated T-suppressor cell inhibition of erythropoiesis in a patient with pure red cell aplasia and chronic T gamma-lymphoproliferative disease

Human retroviruses have recently been linked with T cell lymphoproliferative disorders and with the acquired immune deficiency syndrome. We investigated the mechanisms for acquired pure red cell aplasia and cutaneous anergy in a patient with the chronic T gamma-lymphoproliferative disease (T gamma-LPD) syndrome. Patient marrow erythroid progenitors (BFU-E) were 17 +/- 9% of control and were selectively increased to 88-102% of control after marrow T cell depletion. Patient Leu 2+ suppressor T cells spontaneously produced high titers of human gamma-interferon and resulted in a concentration-dependent selective inhibition (74-91%) of BFU-E when co-cultured with autologous or allogeneic marrow. Conditioned media (CM) derived from patient Leu 2+ T cells similarly inhibited growth of autologous or allogeneic marrow BFU-E. The inhibitory factor derived from patient CM was acid-labile (pH 2) and sensitive to trypsin; prior treatment of patient T cells with anti-HLA-DR monoclonal antibody plus complement abrogated the suppressive effect of T cell-derived CM. Patient peripheral blood mononuclear cells (PBMC) were unable to support growth of cultured interleukin 2 (IL 2)-dependent T cells, but responded to exogenous IL 2 in vitro with a 16-21-fold augmentation, relative to control, in mitogen-induced proliferation. Antibodies to HTLV-I core proteins p19 and p24 but not to HTLV-III proteins were detected in patient serum by Western blotting; patient cultured PBMC stained (7-11%) with antibodies to p19 and p24. Patient cultured PBMC demonstrated integrated HTLV-I genomic sequences by the Southern technique and expressed both specific HTLV-I genomic sequences by RNA dot blot plus reverse transcriptase activity. Utilizing a cloned DNA probe for the beta chain of the T cell receptor gene, patient PMBC demonstrated gene rearrangements providing presumptive evidence for clonality. The presence in serum of HTLV-I p19 and p24 antibodies, the expression of p19 and p24 core antigens on patient mononuclear cells, the evidence of HTLV-I proviral integration sequences and the expression of HTLV-I genomic sequences in patient cells, indicates infection with HTLV-I and raises the possibility of an etiologic link between human retrovirus infection and some instances of large granular lymphocytic leukemia (T gamma-LPD).

A mild uncompensated alkalosis in anemia

Blood, pH and bicarbonate were examined in 40 normal subjects and in 53 patients with anemia. Included were 28 patients with thalassemia, 18 with aplastic anemia and seven with iron deficiency anemia. Mean increases in pH of 0-0.04 and decreases in HCO3 of 2.3-3.5 mEq/L were observed. Changes were not significantly affected by the degree of erythropoiesis or by the severity of the anemia and were essentially the same in the three groups of patients studied. Typical changes of a mild, uncompensated alkalosis were also produced on four occasions in one transfused thalassemic patient.

Survival after antilymphocyte globulin therapy for aplastic anemia depends on disease severity

Sixty-four patients with aplastic anemia were treated with antilymphocyte globulin (ALG Merieux) between 1980 and 1985. The actuarial survival for all patients was 53% at 6 years, with 79% survival for nonsevere aplastic anemia (NSAA) and 36% for severe aplastic anemia (SAA). The neutrophil and platelet counts before treatment with ALG were highly predictive of survival, whereas sex, age, and etiology were not. Duration of disease prior to ALG treatment was inversely related to survival, although this was not statistically significant. Survival was closely associated with response to ALG, especially for patients with SAA. The response to one course of ALG was 33%. Eighteen patients who did not respond to an initial course of ALG received a second course; of these, four (22%) responded. The overall response to one or two courses of ALG was 40%. The mean RBC volume (MCV) measured after ALG treatment was a useful early indicator of response. Both the minimum lymphocyte count during ALG therapy and the mean lymphocyte count after therapy, however, were not significantly different between responders and nonresponders. The disappointing survival of patients with SAA in this study may reflect the poor clinical condition of severely affected patients referred to us and/or the presence of longstanding aplasia. The importance of studying a large series of patients with long-term follow-up to assess ALG in the treatment of aplastic anemia is shown by this investigation.

Gamma-interferon in aplastic anemia: inability to detect significant levels in sera or demonstrate hematopoietic suppressing activity

A radioimmunoassay (RIA) was used to quantitate biologically active gamma interferon (INF-gamma) in sera and in supernatants of cultured mononuclear cells obtained from 50 patients with aplastic anemia. Only five of the 50 serum samples had INF-gamma levels above background (greater than 0 less than 0.5 units per mL). Detectable levels of spontaneous INF-gamma (0.3 to 868 U/mL) were found in 18 of the 50 mononuclear cell supernatants tested. The addition of patient sera or INF-gamma positive supernatants to cultures of normal hematopoietic colonies did not result in reduced colony growth. Flow cytofluorimetric analysis of mononuclear cells failed to establish a correlation between the presence of INF-gamma in supernatants and the number of activated T cells or natural killer (NK) cells in the mononuclear cell population. However, a significant correlation did exist between the presence of monocytes and the production of INF-gamma. Contrary to previous reports, our data suggest that patients with aplastic anemia do not have high circulating levels of INF-gamma. Unstimulated mononuclear cells from some patients will produce significant levels of INF-gamma, but this does not result in decreased in vitro hematopoiesis.

Erythroid marrow function in anemic patients

Erythropoietic activity is known to be closely associated with marrow iron uptake. A modification of the standard measure of plasma iron turnover has been developed in which erythron transferrin uptake (ETU) rather than iron uptake has been calculated. The ETU has the advantage of providing a parameter of erythroid marrow activity independent of change produced by plasma iron and transferrin saturation. Measurements in 80 patients with anemia were compared to the normal value of 60 +/- 12 mumol/L whole blood/d. The mean ETU for ten patients with severe aplastic anemia and for six patients with pure red-cell aplasia were 12 +/- 8 and 12 +/- 11 mumol/L whole blood/d, respectively. In ten transfusion-dependent patients with renal failure under dialysis therapy, the mean value was 35 +/- 11, while ten other dialyzed patients who were transfusion independent had a mean ETU of 73 +/- 21 mumol/L whole blood/d. Sixteen patients with hemolytic anemia had an average ETU of 400 +/- 130, while 28 patients with ineffective erythropoiesis had a mean value of 474 +/- 147 mumol/L whole blood/d. While patients with hypoproliferative anemia showed no relation between the severity of anemia and ETU, those with hyperproliferative erythroid marrow showed increasing values as the anemia became more severe. Sequential measurements in patients with aplastic anemia under treatment and in thalassemic patients under transfusion therapy showed the value of this measurement in monitoring the effects of treatment on erythroid marrow activity. It is concluded that the measurement of ETU provides a more direct ferrokinetic evaluation of erythroid activity in anemic states.

Lung function changes after allogenic bone marrow transplantation

The lung function of 21 patients with leukaemia (11 with acute myeloid leukaemia, six with acute lymphatic leukaemia, four with chronic myeloid leukaemia) and of five with severe aplastic anaemia was tested before and after allogenic bone marrow transplantation. Vital capacity (VC) was lowered in patients with leukaemia before transplantation. VC and FEV1 fell significantly after transplantation. Residual volume (RV) and RV as a percentage of total lung capacity (RV % TLC) were already increased and rose significantly after transplantation. Patients with severe aplastic anaemia had noticeably increased RV and RV % TLC, values that did not change after transplantation. In contrast to the patients with aplastic anaemia, the patients with leukaemia had significantly reduced VC, RV, RV % TLC, and FEV1 before and after transplantation. The specific airway resistance (sRaw) was raised significantly before and after transplantation in the leukaemic patients. In addition, transfer coefficient (Kco) fell significantly more after transplantation in the patients with leukaemia than in those with severe aplastic anaemia. In three patients with histologically established obstructive bronchiolitis in conjunction with chronic graft versus host disease after transplantation, VC, FEV1 and FEV1 % VC fell, while RV, RV % TLC, and sRaw rose; Kco was far below normal. On the basis of these findings it is concluded that in patients with leukaemia obstructive disorders of ventilation develop or, if they are already present, worsen. In patients with severe aplastic anaemia lung function was not impaired in the early phase after transplantation. These differences are probably due to the more intensive immunosuppressive and cytotoxic preparatory regimen before transplantation in the leukaemic patients. Obstructive bronchiolitis, a complication of graft versus host disease, first manifests itself in a typical rise in specific airway resistance and must be treated early.

Participation of bone marrow stromal cells in hemopoietic recovery of rats irradiated and then parabiosed with a non-irradiated litter mate. I. Light microscopic observations

All rats were exposed to whole-body irradiation (1,000 rads by X-rays) to induce aplastic marrows. Control rats received no further treatment. Experimental rats were conjugated three days after irradiation with a non-irradiated healthy litter mate by aortic anastomosis. Control rats died within seven days due to irradiation injury. In these animals, bone marrow reticulum cells were easily distinguished from other stromal cells, such as macrophages or sinusoidal endothelial cells. Three to seven days after irradiation, reticulum cells accumulated lipid droplets in the cytoplasm and showed increases in size and number, resulting in fatty aplastic marrows. On the other hand, parabiosed rats showed hemopoietic recovery and lower levels of lipid droplets in reticulum cells at five to eight days after parabiosis. Progressive fibrosis followed after irradiation but a regression followed after parabiosis. This suggested that fibroblastoid reticulum cells aided in producing collagen fibers. It was also suggested that bone marrow stromal cells, namely, perisinusoidal and intersinusoidal reticulum cells, fat-storage cells, and fibroblastoid cells, shared a common cellular origin. The deserted alterations in reticulum cells after irradiation and the hemopoietic recovery after parabiosis might be due to hemopoietic cells stimulating reticulum cells to induce and sustain the hemopoiesis.

Defective erythroid progenitor differentiation system in congenital hypoplastic (Diamond-Blackfan) anemia

To explore the etiology of congenital hypoplastic or Diamond-Blackfan anemia (DBA) we investigated in vitro erythropoiesis in nine patients. Of the nine, seven were clinically responsive to prednisone. Four were infants evaluated at the time of diagnosis. Six were never or were only minimally transfused. Those for whom prednisone had been prescribed had discontinued the drug a minimum of five months prior to study. The bone marrows of these nine patients were compared with those of hematologically normal individuals and with those of four patients with transient erythroblastopenia of childhood (TEC) whose erythroid aplasia was as severe as that of the patients with DBA. Using the plasma clot semisolid culture technique to enumerate erythroid progenitors and to evaluate the growth characteristics of the colonies to which they give rise, we concluded that at the onset of DBA: (a) erythroid progenitor frequency does not correlate with the degree of anemia and erythroblastopenia; (b) erythroid progenitor differentiation may in some cases be abnormally insensitive to crude preparations of erythropoietin; and (c) progenitor erythropoietin insensitivity in vitro does not necessarily indicate prednisone insensitivity in vivo. Thus, DBA does not appear to be solely the result of deficient formation of erythroid progenitors but is, in addition, a disorder that is due to defective progenitor differentiation in vivo.

The coronary circulation in human septic shock

Reversible myocardial depression, manifested by ventricular dilatation and decreased ejection fraction, is common in human septic shock. A proposed mechanism, based on animal studies, is myocardial ischemia resulting from inadequate coronary blood flow. Coronary flow observations have not been reported for human septic shock. To determine whether myocardial depression in human septic shock is associated with reduced coronary flow, thermodilution coronary sinus catheters were placed in seven patients with septic shock for measurements of coronary flow and myocardial metabolism. Four of the seven patients developed myocardial depression. These patients had coronary flow similar to or higher than that of control subjects and similar to that of the other three patients, who did not develop myocardial depression. None of the patients had net myocardial lactate production. In general, compared with values in control subjects, the oxygen content difference (arterial minus coronary sinus) was narrowed, and the fractional extraction of arterial oxygen was diminished. This pattern of disordered coronary autoregulation is analogous to the pattern of arteriovenous shunting in other organs in patients with septic shock. The preservation of coronary flow, the net myocardial lactate extraction, and the increased availability of oxygen to the myocardium argue against global ischemia as the cause of myocardial depression in human septic shock.

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.

Burst-promoting activity in anemia and polycythemia

Burst-promoting activity (BPA) in the sera of patients with various types of anemia and polycythemia was compared with that of normal subjects by an in vitro method using mouse bone marrow cells. The control culture contained normal human AB serum instead of sample materials. Results were expressed as a percentage of burst numbers in control cultures. Serum erythropoietin (Epo) levels were determined by a radioimmunoassay. Serum BPA in patients with aplastic anemia (155.4 +/- 56.7%, mean +/- SD) was significantly higher than that in normal subjects (112.1 +/- 29.1%, Wilcoxon's rank sum test, P less than 0.05). However, serum BPA in patients with uremic anemia (122.2 +/- 26.5%), polycythemia vera (101.9 +/- 19.5%) and stress polycythemia (115.5 +/- 25.6%) was not significantly different from normal subjects. There was a correlation between serum BPA and Epo titers in patients with aplastic anemia and paroxysmal nocturnal hemoglobinuria (r = 0.81, t test, P less than 0.001).

In vitro CFU-E and BFU-E responses to androgen in bone marrow from children with primary hypoproliferative anaemia: a possible therapeutic assay

The effects of natural and synthetic androgens on erythroid colony formation in children's bone marrow cultures were studied using a methylcellulose microculture assay. In an attempt to predict the clinical response to androgens in two children with Fanconi anaemia (FA) and two children with Diamond-Blackfan syndrome (DB), we tested the hormonal stimulation of testosterone, nortestosterone and etiocholanolone on CFU-E, BFU-E and uroporphyrinogen I synthase activity (UROS). We observed that colony formation and UROS activity were reduced when compared to values obtained with normal children's bone marrow cultures. The addition of steroids to the cultures significantly enhanced the numbers of CFU-E and BFU-E derived colonies and their UROS activity in marrow from patients with FA and one patient with DB. The strong depletion of marrow progenitor cells in the unresponsive marrow from child 4 with DB could explain the absence of hormonal response. Whereas the responsiveness to steroids varied according to the individual, the in vitro testing of erythroid differentiation in the presence of androgens theoretically may lead to an effective prediction of response to therapy in children with hypoplastic anaemia.

Myelopoiesis and erythropoiesis of bone marrow cells cultured in vitro in patients recovered from aplastic anaemia

Methylcellulose culture assay was used to detect committed haemopoietic stem cells, CFU-C and CFU-E, in aplastic anaemia patients with autologous haemopoietic reconstitution. Severe diminution of CFU-C was found in all the patients studied and the absence of a dose-response to colony stimulating factor (CSF) was demonstrated. A reduced number of CFU-E and lower erythropoietin (Ep) sensitivity of those progenitors was detected as well. Autologous serum added to the bone marrow cultures of these patients enhanced the growth of CFU-C but inhibited CFU-E growth. According to the results presented, some residual damage at the stem cell level is suggested.

Primary refractory anemia: clinical and laboratory study of erythropoiesis in 16 patients

Erythropoiesis was studied in vitro in 16 selected patients with primary refractory anemia without excess of blasts who have been followed for an average of 4.8 years. The number of erythroid colonies and bursts grown in vitro from the patients' marrows did not correlate with any parameter of their disease or their prognosis. The response of marrow erythroid precursor cells to erythropoietin was found to be normal. In no case was a serum or IgG inhibitor of erythropoiesis detected either by quantitation of heme synthesized by marrow cells or by the erythroblast cytotoxicity assay. A clinically significant response of the anemia to corticosteroids was noted in three out of 14 patients. Ten patients died during the followup period, eight of them as a consequence of their hematologic disorder. Bone marrow aplasia with pancytopenia developed in six cases, increased number of marrow blasts in two cases, myelofibrosis with myeloid metaplasia in one case and a spontaneous remission in another case. Refractory anemia without excess of blasts is a heterogeneous disorder with variable natural history including evolution into marrow aplasia.

Functionally abnormal marrow stromal cells in aplastic anemia

We studied the myeloid colony-stimulating activity (CSA) of marrow stromal cells (MSC) derived from normal subjects and patients with aplastic anemia, acute leukemia, and other myeloproliferative disorders. CSA of the MSC was determined in a bilayer system. Feeder layers with varying numbers of MSC (10(4) to 2 X 10(5)) were used. Of 40 MSC tested, 39 stimulated myeloid colony formation by the normal target marrow mononuclear cells. The optimal concentration of MSC exhibiting the maximal stimulation of myeloid progenitors (CFU-GM) varied with different MSC. MSC from normal subjects and from patients with acute leukemia and myeloproliferative disorders were potent stimulators of CFU-GM differentiation. In contrast, MSC from patients with aplastic anemia had poor CSA, suggesting that the marrow microenvironment is functionally abnormal in aplastic anemia.

Recurrence of aplastic anemia following cyclophosphamide and syngeneic bone marrow transplantation: evidence for two mechanisms of graft failure

Two patients with aplastic anemia were treated with high-dose cyclophosphamide and marrow transplantation from their normal, genetically identical twin. Both patients rapidly recovered normal marrow function, but marrow failure recurred 13 and 18 months later. Because donor and host pairs were identical twins, these cases of graft failure could not have resulted from the usual cause of graft failure, ie, immunological reactivity of host cells against unshared minor histocompatibility antigens of the donor. These results imply that there are at least two mechanisms responsible for graft failure after marrow transplantation for severe aplastic anemia.

Extramedullary haemopoiesis after bone marrow transplantation

44 patients underwent bone marrow transplantation (BMT) for treatment of severe aplastic anaemia or haematological malignancies. During their post-transplant phase all patients had erythroblasts and granulocytic precursors in their peripheral blood. 15 patients died between day +6 and +346 after BMT and autopsies were performed. The sections of all 15 patients revealed extramedullary haemopoiesis in the spleen. Extramedullary haemopoiesis in the liver was found only in those patients who died early (between d +6 and d +21 after BMT). Medullary haemopoiesis, normally only occurring in the vertebral body, was also observed in the shaft of the femur. The present data show that after BMT all tissues with a haemopoietic matrix in ontogenesis can be repopulated with haemopoiesis in the early phase of reconstitution, possibly to compensate for the haemopoietic insufficiency after conditioning therapy. The expansion of haemopoiesis in the later period of up to 1 year after BMT, remains to be explained.

Interferon is a mediator of hematopoietic suppression in aplastic anemia in vitro and possibly in vivo

We have investigated interferon as a mediator of hematopoietic suppression in bone marrow failure. Interferon production by stimulated peripheral blood mononuclear cells from patients with aplastic anemia was significantly higher than that observed in controls; spontaneous interferon production by these cells was also high for more than half of aplastic anemia patients. Circulating interferon, not detectable in normal individuals, was detected in 10 of 24 patients. Interferon is a potent inhibitor of hematopoietic cell proliferation and, therefore, may be the mediator of suppression in many in vitro models employing patients' cells and sera. The possible pathogenic importance of interferon in aplastic anemia was suggested by an increase in hematopoietic colony formation in vitro after exposure of bone marrow cells to antiinterferon antisera (277 +/- 71% increase for patients compared to 1.6 +/- 1.6% for normal individuals). Interferon levels in the bone marrow sera of aplastic anemia patients were high (mean = 203 international units (IU)/ml, n = 8), even in comparison to circulating levels in the same patients. Normal bone marrow sera also contained measurable interferon but at lower levels (41 IU/ml, n = 16), indicating that interferon may be a normal bone marrow product. High concentration of bone marrow interferon, possibly due to abnormal immunologic activity or a reaction to virus infection of the bone marrow, may mediate hematopoietic suppression in aplastic anemia patients.

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.

Functional changes in marrow stromal cells in aplastic anaemia

To determine whether or not abnormalities exist in the bone marrow stroma in aplastic anaemia, we analysed the ability of marrow stromal cells to support haemopoiesis using a long-term culture system. Marrow stromal cell layers from 3 of 9 patients with this disorder failed to maintain granulocyte-macrophage colony-forming cells in vitro. The stromal dysfunction was reversible in 1 patient who recovered after androgen therapy. The results of the present study add to the available evidence for a functional defect of marrow microenvironments in some cases of aplastic anaemia.

Anaemia in old age

Because accurate diagnosis largely depends on the results of laboratory investigations, clinicians may undervalue their role in asking the right questions, in assessing the patient as a whole, and in consulting with colleagues in haematology. It is this that leads to most errors in diagnosis and treatment.

Regulation of hematopoiesis

These discussions are selected from the weekly staff conferences in the Department of Medicine, University of California, San Francisco. Taken from transcriptions, they are prepared by Drs Homer A. Boushey, Associate Professor of Medicine, and David G. Warnock, Associate Professor of Medicine, under the direction of Dr Lloyd H. Smith, Jr, Professor of Medicine and Chairman of the Department of Medicine. Requests for reprints should be sent to the Department of Medicine, University of California, San Francisco, School of Medicine, San Francisco, CA 94143.

Congenital failure of hematopoiesis in the newborn infant

Hematopoietic stem cell cultures have greatly advanced our understanding of the physiology of blood production at its early stages and have facilitated the study of various factors that regulate cell differentiation and proliferation. With this understanding, the author discusses hematopoiesis, hematopoietic stem cells and assays for their study, and hematopoietic failure. This is followed by a discussion of different forms of bone marrow failure and guidelines for a rational basis for their therapy.

Ectopic bone marrow development in experimental busulfan-induced hypoplastic anemia in mice

The intramuscular implantation of devitalized bone matrix in 42 mice with busulfan-induced bone marrow failure and in 42 control mice led to the sequential formation of ectopic cartilage, bone and bone marrow. The morphological volumetric estimation of these components in the hypoplastic mice showed a significant increase in cartilage and a decrease in hematopoietic bone marrow as compared with control mice. The cellularity in the ectopic hematopoietic bone marrow was similar to that of sternal bone marrow. The possible significance of these findings is discussed.

Testicular function following bone marrow transplantation performed during or after puberty

Testicular function was assessed in eight males who had undergone bone marrow transplantation (BMT) during or shortly after puberty. Their ages ranged between 10 years, 10 months and 17 years, 3 months (median, 13 years, 7 months) at the time of BMT, and they were followed 13 to 77 months (median, 36 months) posttransplantation. Therapy for BMT consisted of high-dose, short-term chemotherapy either alone (Group I) or in combination with single-dose irradiation, total lymphoid (Group II) or total body (Group III). Subjects in Group III had all received combination chemotherapy prior to BMT. Hormonal and clinical evidence of germ-cell dysfunction was common in that 6 patients manifested elevated plasma levels of follicle-stimulating hormone (FSH), and four subjects were found to have a subnormal testicular volume. Of the six patients with abnormal FSH values, four were followed serially, and all showed normalization over time. Leydig cell function was less impaired in that seven of the eight patients produced normal adult male levels of testosterone, including three subjects with elevated luteinizing hormone (LH) levels. All eight developed normal adult male secondary sexual characteristics. It is concluded that the therapy utilized for BMT causes damage primarily to germinal epithelium which appears amenable to recovery. This may be due, in part, to the use of single dose rather than fractionated radiation.