Monocyte-mediated antibody-dependent cellular cytotoxicity: a clinical test of monocyte function.
(1/995)
The lack of a simple, rapid, and quantitative test of the functional activity of the monocyte has hampered studies of the contribution of this cell type to host defense and human disease. This report describes an assay of antibody-dependent cellular cytotoxicity, which depends exclusively upon the monocyte as the effector cell and therefore provides a convenient test of monocyte function. In this system, mononuclear leukocytes (MNL) obtained by Ficoll-Hypaque separation of whole blood are cytotoxic for 51Cr-labeled human erythrocyte targets coated with anti-blood group antibody. Removal of phagocytic monocytes from the MNL by iron ingestion, followed by exposure to a magnetic field, completely abolishes all cytotoxic activity from the remaining MNL population. Similarly, in severely mono-cytopenic patients with aplastic anemia, cytotoxic effector activity is absent. In normals and less severely monocytopenic aplastic anemia patients, cytotoxicity correlates significantly (p less than 0.001) with monocyte number. Application of this monocyte-mediated antibody-dependent cellular cytotoxicity assay to the study of patients with the Wiskott-Aldrich syndrome has revealed defective monocyte cytotoxic activity in spite of normal monocyte numbers, suggesting that this test may be useful for the assessment of monocyte function in a variety of clinical situations. (+info)
Thymic selection by a single MHC/peptide ligand: autoreactive T cells are low-affinity cells.
(2/995)
In H2-M- mice, the presence of a single peptide, CLIP, bound to MHC class II molecules generates a diverse repertoire of CD4+ cells. In these mice, typical self-peptides are not bound to class II molecules, with the result that a very high proportion of H2-M- CD4+ cells are responsive to the various peptides displayed on normal MHC-compatible APC. We show here, however, that such "self" reactivity is controlled by low-affinity CD4+ cells. These cells give spectacularly high proliferative responses but are virtually unreactive in certain other assays, e.g., skin graft rejection; responses to MHC alloantigens, by contrast, are intense in all assays. Possible explanations for why thymic selection directed to a single peptide curtails self specificity without affecting alloreactivity are discussed. (+info)
Rapid autologous marrow recovery and eradication of infectious mononucleosis despite severe immunosuppression following second transplantation for aplastic anemia.
(3/995)
A patient with aplastic anemia failed to respond to immunosuppressive therapy and first marrow transplantation (BMT). Recovery of autologous hematopoiesis was rapid following a second stem cell transplant with a non-myeloablative preparatory regimen. The autologous immune response to infectious mononucleosis (IM) 4 weeks post-transplant was normal despite recent and ongoing severe immunosuppression. (+info)
Fungal prophylaxis by reduction of fungal colonization by oral administration of bovine anti-Candida antibodies in bone marrow transplant recipients.
(4/995)
Candida overgrowth and invasion constitute a serious threat with a high mortality in BMT recipients. Currently available topical antifungal prophylaxis is largely ineffective, and as resistance to existing, absorbable drugs for systemic use is rapidly developing, new forms of therapy are needed. We investigated the effect of oral treatment of BMT recipients with a bovine immunoglobulin product derived from animals immunized against several Candida species. The natural Candida colonization was first followed in 19 patients to establish the colonization pattern. Half of the patients were found to be colonized prior to transplantation and altogether 72% were colonized at some point during follow-up. Those with a high pre-transplant concentration of Candida in saliva (>100 CFU/ml) remained colonized throughout the BMT treatment period. The therapeutic effect was monitored in two other patient groups. The first group consisted of nine patients, where, due to a low number of primary colonized patients, response in colonized patients was suggestive of a therapeutic effect. In the second group, 10 patients with a high level of colonization (>100 CFU/ml) were given 10 g daily of the product in three divided doses. The results suggest a treatment-related reduction in Candida colonization in a majority (7/10) of patients and one patient became completely negative. As no adverse effects were noted, our findings encourage additional studies in immunocompromised, transplant patients. (+info)
Correction of bone marrow failure in dyskeratosis congenita by bone marrow transplantation.
(5/995)
Dyskeratosis congenita is recognized by its dermal lesions and constitutional aplastic anemia in some cases. We report successful allogeneic bone marrow transplantation in two siblings with this disease from their sister, and their long term follow-up. We used reduced doses of cyclophosphamide and busulfan for conditioning instead of total body irradiation. Also, we report late adverse effects of transplantation which are not distinguishable from the natural course of disease. (+info)
Prospective randomized multicenter study comparing cyclosporin alone versus the combination of antithymocyte globulin and cyclosporin for treatment of patients with nonsevere aplastic anemia: a report from the European Blood and Marrow Transplant (EBMT) Severe Aplastic Anaemia Working Party.
(6/995)
We report the results of the first prospective randomized multicenter study of immunosuppressive treatment in patients with previously untreated nonsevere aplastic anemia (AA) as defined by a neutrophil count of at least 0.5 x 10(9)/L and transfusion dependence. Patients were randomized to receive cyclosporin (CSA) alone or the combination of horse antithymocyte globulin ([ATG] Lymphoglobuline; Merieux, Lyon, France) and CSA. The endpoint of the study was the hematologic response at 6 months. One hundred fifteen patients were randomized and assessable with a median follow-up period of 36 months; 61 received CSA and 54 ATG and CSA. In the CSA group, the percentage of complete and partial responders was 23% and 23%, respectively, for an overall response rate of 46%. A significantly higher overall response rate of 74% was found in the ATG and CSA group, with 57% complete and 17% partial responders (P =. 02). Compared with CSA alone, the combination of ATG and CSA resulted in a significantly higher median hemoglobin level and platelet count at 6 months. Fewer patients required a second course of treatment before 6 months due to a nonresponse. In the CSA group, 15 of 61 (25%) patients required a course of ATG before 6 months because of disease progression, compared with only 3 of 54 (6%) in the ATG and CSA group. The survival probabilities for the two groups were comparable, 93% (CSA group) and 91% (ATG and CSA group), but at 180 days, the prevalence of patients surviving free of transfusions, which excluded patients requiring second treatment because of nonresponse, death, disease progression, or relapse, was 67% in the CSA group and 90% in the ATG and CSA group (P =.001). We conclude that the combination of ATG and CSA is superior to CSA alone in terms of the hematologic response, the quality of response, and early mortality, and a second course of immunosuppression is less frequently required. (+info)
Bone marrow transplantation for severe aplastic anemia: the Barcelona Hospital Clinic experience.
(7/995)
BACKGROUND AND OBJECTIVE: The outcome of patients with severe aplastic anemia (SAA) has improved considerably over the last decades. Bone marrow transplantation (BMT) is the treatment of choice in young patients who have an HLA-identical sibling donor. This study analyzes the outcome and factors related to survival in patients with SAA receiving BMT in our institution. DESIGN AND METHODS: Between March 1978 and December 1996, 49 consecutive patients received an HLA-identical sibling marrow transplant for SAA. Median age was 21 years (range, 4 to 47) and 15 (31%) were women. Median interval from diagnosis to transplant was 2.6 months (range, 0.5 to 159). Between 1978 and 1982 all patients were conditioned with cyclophosphamide (CY) alone and received methotrexate (MTX) until day 102 as graft-versus-host disease (GvHD) prophylaxis. From 1983 most patients received CY and thoraco-abdominal irradiation (TAI) as the conditioning regimen and cyclosporin A (CSA) as GvHD prophylaxis. RESULTS: Survival probability at 10 years was 55 +/- 7% with a median follow-up for the surviving patients of 8.5 years. The incidences of graft failure, grade II to IV acute GvHD, and chronic GvHD were 21%, 39.5% and 31%, respectively. In multivariate analysis three factors adversely influenced survival: a) age > or = 30 years (p = 0.05); b) > or = 10 transfusion units pre-BMT (p = 0.008); and c) use of long course MTX for GvHD prophylaxis (p = 0.01). One case of squamous-cell carcinoma occurred in a TAI-treated patient 13 years post-transplantation. INTERPRETATION AND CONCLUSIONS: BMT is effective in young patients with SAA who have an HLA-identical sibling donor, particularly if minimally transfused pre-transplant. The introduction of TAI and CSA to our preparative regimen has led to a remarkably increased survival. (+info)
Fusarium infections in patients with severe aplastic anemia: review and implications for management.
(8/995)
BACKGROUND AND OBJECTIVE: The prognosis of severe fungal infections, such as fusarium infections, in patients with aplastic anemia is directly related to the recovery of bone marrow functions. In this study, in vitro anti-Fusarium activity of granulocytes was investigated, the case of disseminated infection in a child with very severe aplastic anemia is reported, and implications for management of such infective complications are discussed. DESIGN AND METHODS: The in vitro efficiency of PMNL from three untreated, normal blood donors and from two G-CSF-treated WBC donors in contrasting the growth of the Fusarium sp strain isolated from the patient we present was measured by a 3H-glucose uptake inhibition assay and confirmed by microscopic examination. RESULTS: Basic growth inhibitory activity of unstimulated PMNL on Fusarium cells was significantly enhanced in the presence of GM-CSF in all three blood donors tested. In one of the two G-CSF-treated donors, in vitro efficiency of PMNL in contrasting the growth of the fungus increased notably after G-CSF treatment. We report the case of a 3-year-old girl with very severe aplastic anemia unresponsive to conventional immunosuppressant therapy who developed a disseminated fusarium infection. The child initially responded to liposomal amphotericin B and granulocyte transfusions from G-CSF stimulated donors. Subsequently she was given a cord blood stem cell transplantation but died of disseminated infection. INTERPRETATION AND CONCLUSIONS: Including the present case, there are only ten reports of invasive infections caused by the genus Fusarium in aplastic anemia patients and only two of the patients survived. In vitro data seem to suggest that in vivo treatment with rh-G-CSF could have a stimulatory effect on the anti-Fusarium activity of neutrophils. Despite the efficacy of granulocyte transfusions by G-CSF-stimulated donors in the temporary control of fusarium infection, treatment of the underlying hematologic disease is required to cure the infection in patients with severe aplastic anemia. Granulocyte transfusions by G-CSF-stimulated donors while awaiting bone marrow recovery following the blood stem cell transplant should be considered. (+info)