Immune suppression of hematopoiesis

Autoimmune hepatitis type 1 and primary biliary cirrhosis have distinct bone marrow cytokine production

We have recently reported differences in the hematopoiesis between autoimmune hepatitis type 1 (AIH-1) and primary biliary cirrhosis (PBC). In view of the notion that cytokines are regulators of hematopoiesis, we investigated in our tertiary center the cytokine production in the bone marrow (BM) of the same consecutive cohort of patients (13 AIH-1, 13 PBC, 10 healthy and 7 patients with cirrhosis due to chronic hepatitis B). Interferon-gamma (IFN-gamma), interleukin-4 (IL-4), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) were determined in the supernatants of long-term BM cultures by ELISAs. IL-4, TNF-alpha and TGF-beta were found significantly increased in the BM of PBC patients compared to AIH-1 and both control groups. AIH-1 patients had significantly higher BM IL-10 compared to PBC patients and higher IL-10, IL-4 and TNF-alpha compared to controls. BM IFN-gamma was significantly higher in PBC and AIH-1 patients compared to controls. In AIH-1 patients, IL-10 was positively correlated with CD34+, CD34+/CD38- and CD34+/CD38+ cell proportions. In conclusion, the BM cytokine microenvironment of PBC and AIH-1 patients differs significantly compared to that of healthy individuals and cirrhotic patients of non-autoimmune etiology. Differences were also found between patients with PBC and AH-1. The implication of BM in the pathogenesis of autoimmune liver diseases is possible and needs further investigation.

Bone Marrow Clonogenic Capability, Cytokine Production, and Thymic Output in Patients with Common Variable Immunodeficiency

In patients with primary Ab deficiencies, hematological and immunological abnormalities are frequently observed. A regenerative failure of hemopoietic stem/progenitor cells has been hypothesized. We evaluated in the bone marrow (BM) of 11 patients with common variable immunodeficiency, the phenotype of BM progenitors and their in vitro growth by colony-forming cell (CFC) and long-term culture (LTC) assays. A significant decrease in erythroid and mixed CFC and, to a greater extent, in primitive LTC-CFC progenitors was observed in patients compared with healthy controls. The frequency of BM pre-B and pro-B cells correlated directly with the absolute number of CD19+ lymphocytes. BM cells cultured in vitro produced spontaneously lower amounts of IL-2 and elevated levels of TNF-alpha compared with controls, indicating a skewing toward a proapoptotic cytokine pattern. In addition, stromal cells generated after BM LTC secreted less IL-7 and displayed by immunohistochemistry an altered phenotype. These findings were associated with a significant decrease in naive Th cells coexpressing CD31 in the peripheral blood. These results indicate an impaired growth and differentiation capacity of progenitor cells in patients with common variable immunodeficiency.

Impaired bone marrow hematopoietic progenitor cell function in rheumatoid arthritis patients candidated to autologous hematopoietic stem cell transplantation

We have evaluated bone marrow morphology, percentage of bone marrow CD34(+) cells, proliferative activity of bone marrow precursors, clonogenic assay (BFU-E and CFU-GM) in short-term bone marrow cultures, and bone marrow cell apoptosis, together with serum TNF-alpha and IL-6, in 16 chronic, refractory RA patients, as well as in five healthy controls. Of 16 RA patients (68.7%), 11 showed a reduced bone marrow cellularity, while it was normal in all the controls. In RA patients, the median percentage of CD34(+) bone marrow cells, the median percentage of proliferating bone marrow myeloid precursors, and the median number of both BFU-E and CFU-GM colonies were significantly lower than observed in the controls. As far as TNF-alpha and IL-6 titers is concerned, the latter did not significantly differ from controls' values, while TNF-alpha titers were significantly lower in healthy controls. Finally, the median apoptotic index of early bone marrow myeloid cells of RA patients was significantly higher compared with controls. These observations may identify the biological risk factors for impaired mobilization and/or engraftment when RA patients are candidates for autologous hematopoietic stem cell grafting.

Hemopoietic progenitor cells and bone marrow stromal cells in patients with autoimmune hepatitis type 1 and primary biliary cirrhosis

BACKGROUND/AIMS

Autologous hematopoietic stem cell transplantation has been used in severe cases of autoimmunity. We investigated whether hemopoietic progenitor cells and/or bone marrow (BM) microenvironment are affected in autoimmune hepatitis type-1 (AIH-1) and primary biliary cirrhosis (PBC).

METHODS

We studied 13 AIH-1 patients, 13 PBC patients, 12 cirrhotic controls (CC) and ten healthy controls (HC). Flow cytometry, expansion cultures, long-term BM cultures and clonogenic progenitor cell assays were used. Stromal cell function was assessed in long-term BM cultures recharged with normal CD34+ cells.

RESULTS

AIH-1 had increased CD34+, CD34+/CD38+ and CD34+/CD38- cells compared to all groups (P<0.001). PBC had lower progenitor cells compared to controls (P<0.005). No differences were found between CC and HC. Committed progenitor cells in non-adherent cell fraction were increased in AIH-1 (P<0.05) but decreased in PBC compared to controls (P<0.05). Granulocyte-macrophage colony forming units (CFU) and erythroid-burst CFU were increased in AIH-1 compared to all groups (P<0.001). PBC had these CFUs decreased compared to controls (P<0.005). Stromal cells failed to support normal hemopoiesis in PBC.

CONCLUSIONS

We demonstrated for the first time that AIH-1 had increased hemopoietic progenitor cells and normal stromal function. In PBC, progenitor cells and BM microenvironment were defective. Further studies will determine the significance of these novel findings.

Aplastic anemia complicating systemic lupus erythematosus: successful management with cyclosporine

Anemia is common with connective tissue disorders, but pancytopenia is rare. We report a 22-year-old female who presented with menorrhagia, seizures, anemia, leukocytosis, thrombocytopenia, pericardial effusion, positive ANA, and evidence of vasculitis on CT head scan and was diagnosed with systemic lupus erythematosus (SLE). After 7 months of remission, she was readmitted with menorrhagia and pancytopenia. Investigations revealed aplastic anemia. She survived on transfusion support for 6 weeks, during which period she received methylprednisolone and cyclophosphamide pulses, and phenytoin was omitted but to no avail. Cyclosporine (300 mg/day) was started and the aplastic anemia responded. After 4 months of therapy, the cyclosporine was gradually tapered over the next 2 months. The patient has been on 10 mg/day of prednisolone for the last 6 months. Aplastic anemia is rare in SLE and the response to immunosuppressants is variable, but here is a success story.

A new model of busulphan-induced chronic bone marrow aplasia in the female BALB/c mouse

Aplastic anaemia (AA) is characterized by hypocellular marrow, pancytopenia, and risk of severe anaemia, haemorrhage and infection. AA is often idiopathic, but frequently occurs after exposure to drugs/chemicals. However, the pathogenesis of AA is not clearly understood, and there are no convenient animal models of drug-induced AA. We have evaluated regimens of busulphan (BU) administration in the mouse to produce a model of chronic bone marrow aplasia showing features of human AA. Mice were given 8 doses of BU at 0, 5.25 and 10.50 mg/kg over 23 days; marrow and blood samples were examined at 1, 19, 49, 91 and 112 days after dosing. At day 1 post dosing, in mice treated at 10.50 mg/kg, nucleated marrow cells, CFU-GM and Erythroid-CFU were reduced. Similarly, peripheral blood erythrocytes, leucocytes, platelets and reticulocytes were reduced. At day 19 and 49 post dosing, there was a trend for parameters to return towards normal. However, at day 91 and 112 post dosing, values remained significantly depressed, with a stabilized chronic bone marrow aplasia. At day 91 and 112 post dosing, marrow cell counts, CFU-GM and Erythroid-CFU were decreased; marrow nucleated cell apoptosis and c-kit+ cell apoptosis were increased; peripheral blood erythrocyte, leucocyte, and platelet counts were reduced. We conclude that this is a model of chronic bone marrow aplasia which has many interesting features of AA. The model is convenient to use and has potential in several areas, particularly for investigations on mechanisms of AA pathogenesis in man.

Bone marrow stem cells and stromal cells in autoimmune cytopenias

High-dose immunosuppression followed by autologous haemopoietic stem cell transplantation (ASCT) is a promising practice for the treatment of severe, resistant autoimmune disorders. Patients with refractory autoimmune cytopenias (AIC), primary or secondary to systemic autoimmune diseases (AID) including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), have been proposed as potential candidates for such a therapeutic procedure. An abnormal immune milieu, however, may affect the number and functional characteristics of stem cells and/or stromal cells in the bone marrow (BM) and might impact on harvesting and engraftment potential of stem cells or on BM reconstitution following engraftment in patients with AIC undergoing ASCT. Using flow cytometry and in vitro culture assays we have shown that patients with primary AIC display increased number of BM CD34+ cells in response to abnormally high production of granulocyte-colony stimulating factor (G-CSF) by BM stroma. In contrast, patients with AIC secondary to systemic AID display increased apoptosis of BM progenitor cells resulting in low CD34+ cell numbers and abnormal haemopoiesis supporting capacity of BM stroma due to the aberrant, local or systemic, inhibitory cytokine production or to intricate interactions between haemopoietic and immune cells present within the BM microenvironment. In this review we summarize the available knowledge on BM stem cell reserve and function and stromal cell function in patients with primary and secondary AIC with special reference to SLE and RA. The underlying mechanisms possibly involved in the pathogenesis of the observed abnormalities are also discussed.

Bone marrow progenitor cell reserve and function and stromal cell function are defective in rheumatoid arthritis: evidence for a tumor necrosis factor alpha-mediated effect

Based on previous reports for impaired hematopoiesis in rheumatoid arthritis (RA), and in view of the current interest in exploring the role of autologous stem cell transplantation (ASCT) as an alternative treatment in patients with resistant disease, we have evaluated bone marrow (BM) progenitor cell reserve and function and stromal cell function in 26 patients with active RA. BM progenitor cells were assessed using flow cytometry and clonogenic assays in short-term and long-term BM cultures (LTBMCs). BM stroma function was assessed by evaluating the capacity of preformed irradiated LTBMC stromal layers to support the growth of normal CD34(+) cells. We found that RA patients exhibited low number and increased apoptosis of CD34(+) cells, defective clonogenic potential of BM mononuclear and purified CD34(+) cells, and low progenitor cell recovery in LTBMCs, compared with healthy controls (n = 37). Patient LTBMC stromal layers failed to support normal hematopoiesis and produced abnormally high amounts of tumor necrosis factor alpha (TNF alpha). TNF alpha levels in LTBMC supernatants inversely correlated with the proportion of CD34(+) cells and the number of colony-forming cells, and positively with the percentage of apoptotic CD34(+) cells. Significant restoration of the disturbed hematopoiesis was obtained following anti-TNF alpha treatment in 12 patients studied. We concluded that BM progenitor cell reserve and function and BM stromal cell function are defective in RA probably due, at least in part, to a TNF alpha-mediated effect. The role of these abnormalities on stem cell harvesting and engraftment in RA patients undergoing ASCT remains to be clarified.

Assessment of bone marrow stem cell reserve and function and stromal cell function in patients with autoimmune cytopenias

To investigate whether bone marrow (BM) stem cell compartment and/or BM microenvironment are affected by the immune insult in autoimmune cytopenias (AICs), BM stem cell reserve and function and BM stromal function were studied in 15 AIC patients. Stem cells were evaluated by means of flow cytometry, clonogenic progenitor cell assays, long-term BM cultures (LTBMCs), and limiting dilution assay for quantification of long-term–culture initiating cells (LTC-ICs). Stromal cell function was assessed with the use of preformed irradiated LTBMCs from patients and normal controls, recharged with normal CD34+ cells. AIC patients exhibited a high number of CD34+, CD34+/CD38+, and CD34+/CD38− cells; high frequency of granulocyte-macrophage colony forming units in the BM mononuclear cell fraction; high colony recovery in LTBMCs; and normal LTC-IC frequency. Patient BM stromal layers displayed normal hematopoietic-supporting capacity and increased production of granulocyte-colony stimulating factor. Data from this study support the concept that AIC patients with severe, resistant disease might be appropriate candidates for autologous stem cell transplantation.

Assessment of bone marrow stem cell reserve and function and stromal cell function in patients with autoimmune cytopenias

To investigate whether bone marrow (BM) stem cell compartment and/or BM microenvironment are affected by the immune insult in autoimmune cytopenias (AICs), BM stem cell reserve and function and BM stromal function were studied in 15 AIC patients. Stem cells were evaluated by means of flow cytometry, clonogenic progenitor cell assays, long-term BM cultures (LTBMCs), and limiting dilution assay for quantification of long-term–culture initiating cells (LTC-ICs). Stromal cell function was assessed with the use of preformed irradiated LTBMCs from patients and normal controls, recharged with normal CD34+ cells. AIC patients exhibited a high number of CD34+, CD34+/CD38+, and CD34+/CD38− cells; high frequency of granulocyte-macrophage colony forming units in the BM mononuclear cell fraction; high colony recovery in LTBMCs; and normal LTC-IC frequency. Patient BM stromal layers displayed normal hematopoietic-supporting capacity and increased production of granulocyte-colony stimulating factor. Data from this study support the concept that AIC patients with severe, resistant disease might be appropriate candidates for autologous stem cell transplantation.

Bronchocentric granulomatosis associated with pure red cell aplasia and lymphadenopathy

Bronchocentric granulomatosis developed in a patient with previously diagnosed pure red cell aplasia and lymphadenopathy. There was an excellent response to corticosteroid treatment. An immunological pathogenesis common to bronchocentric granulomatosis and pure red cell aplasia is suggested.

Treatment of aplastic anaemia with antilymphocyte globulin and high-dose methylprednisolone

Twenty-three consecutive adults with bone marrow aplasia who, apart from one individual, lacked a sibling suitable for allogeneic transplantation, received five daily infusions of 50 mg/kg of antilymphocyte globulin (ALG) concurrently with high-dose (500 mg) methylprednisolone (HDMP), followed by oral prednisone at a dose of 30 mg until day 30. One patient died early so that response could not be determined, but data are available and included in the toxicity as well as survival analysis. Haematological response occurred in 13 of the remaining 22 (59%). This followed a single course of treatment in 12, with complete response achieved in five of this group and a second course required in one. At a median follow-up of 20 months (range 5-60), there have been five relapses and 13 patients are alive, including 12 responders who have Karnofsky ratings between 90% and 100%. Of the other nine individuals, only two are alive, with 1 at 12 months still requiring active support and the second, after failing further courses of treatment, at 41 months having a partial response to lymphocytapheresis and plasma exchange. Failure to respond was a significant adverse predictor for survival (P = 0.022). This study involved two distinct batches of ALG, with response occurring in 1/7 (14%) patients treated with the first lot, but in 12/15 (80%) of those individuals who were treated with the second (P = 0.007). Only a pretreatment mean cell volume (MCV) greater than 100 fL predicted for response (P = 0.0088). Confirmation is hereby provided for the efficacy of ALG used in combination with HDMP for treatment of aplastic anaemia, with further support for the observation that not all batches of this product are comparable in bringing about haematologic response in these individuals.

Multiple responses of aplastic anemia to low-dose cyclosporine therapy despite development of a myelodysplastic syndrome

A 55-year-old white woman presented in July 1984 with severe aplastic anemia refractory to anti-thymocyte globulin, corticosteroids, and danazol. In December 1984, oral cyclosporine therapy was begun, and a partial remission was achieved with persistent thrombocytopenia and transfusion independence. The cyclosporine dosage was tapered and then stopped in May 1986 when the platelet count was 35,000/L. In October 1986 the platelet count was only 16,000/L, and the bone marrow showed evidence of a myelodysplastic syndrome; cytogenetic analysis revealed deletion of the long arm of chromosome 13 (previous cytogenetic findings had been normal). After cyclosporine therapy was resumed, platelet count promptly increased to 36,000/L. A subsequent attempt to taper the cyclosporine dosage resulted in a decreased platelet count. The platelet count responded to cyclosporine again and was maintained at 54,000/L and higher with cyclosporine therapy at only 25 mg/day. This information suggests that, despite the development of a myelodysplastic syndrome, immune mechanisms were still operative in the pathogenesis of our patient's thrombocytopenia. Immune modulation may have an important role in preventing progression of myelodysplastic syndromes to more severe forms or to acute leukemia.

A report of a case with pure red cell aplasia induced by sodium valproate

A 5-year-old girl developed pure red cell aplasia (PRCA) during sodium valproate (VPA) administration. Only four cases of VPA induced PRCA have been reported in the literature. Furthermore no precise report concerning the underlying mechanisms is available. Using a system for the clonal growth of autologous bone marrow committed erythroid stem cells (CFU-E, BFU-E) VPA itself was not inhibitory for colony formation at a physiological concentration. Patient's serum and peripheral mononuclear cells collected at admission showed no inhibitory effects on erythroid progenitor cell growth. Rapid recovery from PRCA was observed after discontinuation of VPA, without immunosuppressive therapy. Our observation suggests that VPA may induce PRCA through the inhibitory effect beyond the differentiation stage of BFU-E and CFU-E in some cases.

Structure and regulation of the erythroid system at the level of progenitor cells

Considerable ground has been covered since the first clonal assays for hemopoietic cells were described. The possibility of studying populations of progenitor cells and the regulatory factors that influence them has already thrown considerable light on our understanding of the structure and physiology of the normal erythroid system and its alterations in disease. The relative importance of humoral and short-range factors and of possible cell-to-cell interactions in the regulation of proliferation and differentiation in the erythroid cell lineage is now being studied actively in several laboratories. The possibility of analyzing possible regulatory networks involving such highly reactive cells as lymphocytes and monocytes-macrophages in defined in vitro conditions now exists. As these studies are being extended to the diseased state, concepts related to alterations in regulatory mechanisms in syndromes with abnormal cell proliferation can be tested. Clinical applications in the treatment of patients with hematological disease are being contemplated. The usefulness of Epo for the treatment of the anemia of renal disease has been demonstrated already.

Aplastic anemia associated with in vitro inhibition of erythropoiesis by bone marrow-adherent cells

A patient with aplastic anemia that evolved following pure red cell aplasia is described. Cultures of the patient's marrow cells revealed greatly reduced numbers of primitive (BFU-E) and relatively mature (CFU-E) erythroid progenitors, but normal numbers of multipotential (CFU-GEMM) precursors. The BFU-E/CFU-GEMM and CFU-E/BFU-E ratios in the patient's marrow cell cultures were also reduced. T cell- or antibody-mediated inhibition of in vitro erythropoiesis could not be demonstrated in this patient. However, the patient's marrow-adherent cells suppressed the growth of autologous and allogeneic BFU-E and CFU-E, without influencing the growth of CFU-GEMM. Medium conditioned by the patient's adherent cells failed to inhibit the growth of normal erythroid precursors. Our findings suggest a role for marrow-adherent cells in the pathogenesis of aplastic anemia in this patient.

Aplastic anaemia complicating adenovirus infection in DiGeorge syndrome

An 18-month-old child with partial DiGeorge syndrome developed aplastic anaemia during an acute adenovirus infection. Assessment of the child's immune system revealed T-cell subset abnormalities consistent with DiGeorge syndrome. A possible link between the underlying immune deficiency and the observed complication is suggested.

Immunoarchitecture of the bone marrow in neutropenia: increased HNK-1 + cells define a subset of neutropenic patients

An immunoperoxidase technique was used to examine the distribution of lymphocyte subsets in bone marrow biopsies of 15 patients with neutropenia and seven non-neutropenic controls. The bone marrow of most patients and controls had similar distributions of immune effector cells characterized by a diffuse array of predominantly cytotoxic/suppressor T-cells and occasional nodular aggregates of helper T-cells. Cells displaying the natural killer cell marker HNK-1 were sparse in controls and most neutropenic patients. However, marked increases in marrow HNK-1 + cells were identified in four of the 15 patients. Three of these patients had diffuse HNK-1 + infiltrates associated with increased Leu 4+ (OKT-3+) T-cells while one had a nodular HNK-1+ infiltrate associated with small B-cell follicles. Each of these patients had clinical features similar to those described in the large granular lymphocyte (LGL) lymphocytosis (leukemia) syndrome, but only one of four demonstrated persistently increased numbers of LGLs in the peripheral blood. Thus, this study extends the association of neutropenia and increased numbers of cells with a T/NK phenotype to include patients whose bone marrow is the only demonstrable site of involvement. Since morphologic examination of the bone marrow could not identify the bone marrows with increased HNK-1+ cells, immunologic techniques are required to detect these cases.

Simultaneous transient erythroblastopenia and agranulocytosis: IgG-mediated inhibition of erythrogranulopoiesis

We report a case of simultaneous transient erythroblastopenia and agranulocytosis recovering spontaneously. In vitro study using autologous bone marrow cells after recovery demonstrated IgG-mediated inhibition of both erythropoiesis and granulopoiesis but not megakaryopoiesis. The inhibitory activity disappeared shortly after remission. These findings suggest that IgG-mediated inhibition of hematopoiesis may be pathogenetic for transient bone marrow failure of the patient.

Efficacy of danazol in pure red cell aplasia

Twenty-one unselected patients with refractory chronic anemias of various etiologies were treated with danazol, a synthetic attenuated androgen. All had previously failed treatment with hematinics, androgens, corticosteroids, high-dose intravenous immunoglobulin, antithymocyte globulin, cytotoxic immunosuppressive agents, and/or plasmapheresis. Three patients with pure red cell aplasia and one with aplastic anemia responded. No responses were observed in 11 patients with myelodysplastic syndromes, two patients with myelofibrosis, and two with paroxysmal nocturnal hemoglobinuria. Remission in pure red cell aplasia was maintained with danazol alone in one patient and required combined low-dose prednisone in two. Objective responses occurred in 2 to 3 weeks and therapy generally was well tolerated. To date, one patient with pure red cell aplasia remains in complete remission at 9 months on low-dose danazol alone. We conclude that danazol alone or combined with prednisone may induce and maintain remission in severe refractory pure red cell aplasia and possibly other chronic cytopenias characterized by immunologic marrow suppression. Further trials of danazol in treating these disorders are indicated.

Indoprofen-induced aplastic anemia in active connective tissue disease detected by drug-specific lymphocyte transformation

In connective tissue diseases, the differentiation of disease-related hematological aberrations from drug-induced cytotoxic or allergic blood-cell dyscrasias is often difficult. In this paper we report on the positive identification of an indoprofen-induced severe pancytopenia in a multi-drug-treated patient with active systemic lupus erythematosus by use of a drug-specific lymphocyte transformation test.

Long-term remission of pure red cell aplasia after plasma exchange and lymphocytapheresis

A 57-year-old man with idiopathic pure red cell aplasia went into remission after plasma exchange. He relapsed after 5 months and then failed to respond to treatment with intensive plasma exchange and immunosuppressive agents. Because of a high proportion of T-suppressor cells in the peripheral blood he was treated with lymphocytapheresis in addition to the previous treatment. The patient achieved a long-term haematological remission which has now persisted for more than 3 yr.

Neutropenia and thrombocytopenia: antibodies directed against circulating neutrophils and bone marrow myeloid progenitor cells (CFU-C)

The pathophysiology of a neutropenic disorder was evaluated in a 60-year-old man using myeloid progenitor cell (CFU-C), colony stimulating activity (CSA), and antineutrophil antibody assays. An immunoglobulin, present in the patient's serum at presentation, was directed against peripheral blood neutrophils, and autologous and allogeneic bone marrow CFU-C. A course of prednisone resulted in resolution of the neutropenia and a disappearance of the cytotoxic antibody. This study suggests that the patient's neutropenic disorder resulted from antibody-mediated destruction of circulating neutrophils and a suboptimal bone marrow granulopoietic response.

Release of granulocyte-macrophage colony-inhibiting activity by normal human postthymic precursor cells

Seven normal human peripheral blood cell fractions (buffy coat, mononuclear cells, non-T, T, Fc-IgM receptor-depleted T-lymphocyte, Fc-IgG receptor-depleted T-lymphocyte, and autologous rosette-forming T-cell-depleted T-lymphocyte subpopulations) treated with phytohemagglutinin (PHA) were examined for the production of granulocyte-macrophage colony-stimulating activity (CSA). It was found that medium conditioned by a T-lymphocyte subpopulation depleted of autologous rosette-forming T-cells (Tar cells, a postthymic precursor subpopulation that inhibits Ig synthesis) stimulated colony-forming units of granulocyte and macrophages (CFU-GM) to a greater extent than did the other conditioned media (CM) analyzed. Based on this finding, CM from an enriched Tar subpopulation was prepared and thus showed that PHA-treated Tar cells release a factor capable of inhibiting CFU-GM growth. The inhibitory activity of this factor persisted-after heat inactivation, suggesting that cause of the colony-inhibiting activity (CIA) is other than interferon. Further studies revealed that Tar-derived inhibitory factor acts either directly upon CFU-GM or via monocytes/macrophages (M phi/Ma), enhancing CIA, and not the level of CSA production by M phi/Ma. The overall data are interpreted as demonstrating the presence of CIA in a specific T-lymphocyte subpopulation that may represent a new relationship between lymphocytic and myelocytic systems in the human.

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.

Hematologic abnormalities in the acquired immune deficiency syndrome

Blood and marrow specimens were evaluated from 12 patients with the acquired immune deficiency syndrome (AIDS). Ten patients were anemic, eight leukopenic, and three thrombocytopenic. Pancytopenia was present in two patients and subsequently developed in two others. Reticulocyte counts were not increased in the anemic patients. The most common peripheral blood abnormalities were a left shift in the granulocyte series, lymphopenia, atypical lymphocytes, and vacuolated monocytes. Marrow cellularity was increased in five patients and reduced in three. Marrow reticulin was increased in 10 patients; in three of these, marrow could not be obtained by aspiration. Plasma cells were increased in number in every marrow aspirate, and there was a left shift in the myeloid series in most. Aggregates of atypical lymphocytes or a diffuse increase in marrow lymphocytes occurred in seven patients. An increase in histiocytes was observed in seven marrow aspirates; in five of these, the histiocytes were phagocytizing red cells, white cells, and platelets. Necrosis was present in four marrow specimens. These hematologic abnormalities reflect, in part, the presence of systemic infection, inflammation, and the inanition associated with them. However, the high incidence of myelofibrosis, alterations in marrow cellularity, pancytopenia, and hematophagic histiocytosis indicates that the bone marrow is a target organ in AIDS.

Lymphocyte subsets in patients with aplastic anemia

Lymphocyte subsets were enumerated in a group of 31 patients with aplastic anemia. Abnormal numbers of immunoregulatory T-cells were found in some patients: 26% of them showed a reversed helper/suppressor ratio. Seven of 18 patients showed significantly decreased proliferation in response to PWM; this hyporesponsiveness was present in 75% of patients with a reversed helper/suppressor ratio and in 10% of those with a normal helper/suppressor ratio (R = 0.66, P = 0.008). Eight of 18 patients showed suppressor activity over PWM-induced allogeneic cell proliferation. This suppressive activity did not correlate with T-cell phenotype. Of the patients with a low number of T-cells, 73% had responded to treatment, whereas of those patients with a normal number of T-cells, 26% had responded (P = 0.016). The results are consistent with abnormal immune response in selected patients with aplastic anemia, and suggest a possible influence of T-cells on disease process.

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.

Response of agranulocytosis to prolonged antithymocyte globulin therapy

A girl with a history of autoimmune disease developed life-threatening agranulocytosis. A bone marrow biopsy demonstrated selective granulocytic hypoplasia. No antineutrophil antibodies were found. In vitro bone marrow culture of granulocytic progenitor cells suggested T cell-mediated inhibition of colony formation, which was reduced by in vitro treatment of marrow cells with either hydrocortisone or an antibody directed against T-lymphocytes and complement. The patient responded to treatment with antithymocyte globulin after administration of corticosteroids and other immunosuppressants failed to increase her neutrophil count significantly. Attempts to stop ATG treatment resulted in precipitous drops in her neutrophil counts, which reversed with readministration of ATG. She then received weekly ATG infusions for over 24 months until she was able to maintain a normal neutrophil count. A trial of ATG therapy may be indicated in severe neutropenia when in vitro culture results indicate a possible autoimmune basis.

Transient erythroblastopenia of childhood: varied pathogenesis

The mechanism of anemia in four patients with transient red cell aplasia of childhood ("erythroblastopenia") was studied at the time of diagnosis by assessing the colony growth of marrow erythroid progenitors in methylcellulose tissue cultures. Marrow from Patient 1 yielded high normal numbers of BFU-E colonies that were completely abolished on addition of autologous serum or IgG. Patient 2 had normal BFU-E growth that markedly declined when autologous serum or IgM was added to the cultures, but growth remained unchanged with added autologous IgG or peripheral blood mononuclear cells (PBMC). Marrow from Patient 3 yielded low CFU-E and BFU-E numbers with standard plating techniques, but colonies strikingly increased when marrow fractions from an albumin density gradient were cultured. PBMC from Patient 3 suppressed control marrow CFU-E and BFU-E, but serum had no effect. Patient 4 had normal CFU-E and BFU-E that increased with autologous serum and remained unchanged with autologous PBMC. We conclude that the red cell aplasia in Patients 1, 2, and 3 was due to suppressed erythropoiesis via IgG, IgM, and cell-mediated inhibition, respectively. In contrast, in Patient 4 no immune mechanism was demonstrated. Whereas transient red cell aplasia has a uniform clinical presentation, there are at least four pathogenetic mechanisms that can be detected 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.

Anemia associated with rheumatoid disease. Inverse correlation between erythropoiesis and both IgM and rheumatoid factor levels

Cell culture techniques were used to evaluate the number of erythroid colonies formed by circulating progenitor cells from 24 patients with rheumatoid disease and controls. A highly significant inverse correlation was demonstrated between erythroid colony counts and serum IgM and rheumatoid factor concentrations in the rheumatoid patients. The potential role of these factors in the pathogenesis of the anemia of rheumatoid disease is discussed.