Pharmacology of agents used in bone marrow transplant conditioning regimens.
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Biomedical subjects
Publications and source records attributed to J M Rappeport.
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Inhibition of normal mouse hemopoietic stem cells by leukemic cells (C1498) was observed with use of in vitro agar and in vivo diffusion-chamber cultures. The C1498 cells were unresponsive to colony-stimulating activity, and, above a critical threshold, they inhibited normal granulocyte progenitors in agar culture. C1498 cells added to normal marrow in diffusion chambers progressively reduced granulocyte progenitors. The larger, more rapidly growing, C1498 cells showed the most inhibitory effect. Transmembrane culture of C1498 cells adjacent to normal marrow in double diffusion chambers for five to 14 days led to reduction of recovery of granulocyte progenitors (72 +/- 7 per cent of control) and pluripotent stem cells (45 +/- 7 per cent of control) from the normal marrow chambers. These results indicate that leukemic mouse cells inhibit normal mouse-marrow stem cells by releasing a diffusible substance, and this inhibition occurs primarily at the level of the pluripotent stem cell.
The capacity of peripheral blood mononuclear cells from bone marrow transplant recipients to proliferate and produce interferon in response to mitogens and specific antigens was tested. Proliferation in response to phytohemagglutinin or pokeweed mitogen occurred in cells from more than 90% of the recipients, and interferon was present in 60 to 70% of the supernatants from these cultures, even when tested as soon as 8 weeks after transplantation. Proliferation in response to bacterial antigens was infrequent, and interferon release was not detected. In the early post-transplantation period (less than 13 weeks), cells from only two of four cytomegalovirus (CMV) antibody-positive patients proliferated normally in response to CMV antigen and interferon release was detected only once. In the late post-transplantation period (more than 13 weeks), in only two of five instances did cells proliferating in response to CMV antigen release interferon. The response to CMV antigen of mononuclear cells from many transplant recipients differs from that of cells from normal controls.
A child with severe neutrophil dysfunction and intractable infections received bone marrow transplants from histocompatible siblings. After a first transplant preceded by cyclophosphamide (CY), antithymocyte serum (ATS) and procarbazine (PCB) preconditioning, there was no evidence for engraftment and autologous marrow function rapidly returned. Cell mediated lysis showed no evidence of patient sensitization against the marrow donor suggesting that graft rejection did not cause the transplant failure. A second transplant was performed utilizing another matched sibling donor. Total body irradiation was added to CY, ATS, and PCB for preconditioning after in vitro studies of the colony forming capacity (CFUc) of the patient's marrow cells showed normal sensitivity to radiation. Full engraftment ensued with correction of granulocyte function abnormalities. The patient eventually died of intractable pulmonary disease. Our experience with this child suggests that cyclophosphamide alone may be insufficient preparation for marrow transplantation in some patients with non-neoplastic hematologic disorders. Experimental and clinical data supporting this contention are reviewed.
[111In]Indium chloride scans of the bone marrow were performed in 22 patients with idiopathic aplastic anaemia before therapeutic intervention. In 20 patients there was a marked reduction in the uptake of indium chloride by the marrow, and in two patients the uptake of indium chloride was normal. Nineteen of the 20 patients with reduced marrow uptake of indium chloride, who underwent bone marrow transplantation, died or failed to improve. One of the two patients with normal scans improved and the other has remained stable. Four patients studied both pre and post successful bone marrow transplantation had minimal marrow uptake before transplantation and normal scans after transplantation. Failure of indium-111 choride marrow uptake correlates with poor prognosis in idiopathic aplastic anaemia.
A prospective randomized trial of therapy for severe aplastic anemia was designed to compare early bone marrow transplantation with conventional treatments. All patients with a sibling matched at the major histocompatibility region were transplanted. Transplantation was performed with 17-100 (median 33) days of original diagnosis. Conventional treatments included transfusion support with or without androgens. Twenty-four of 36 patients intered on the transplant arm are alive after 4-20 (median 9) mo with full marrow reconstitution. Only two are limited by chronic graft-versus-host disease. In contrast only 12 of 31 conventionally treated patients are alive. Six of these survivors have improved, five incompletely. The 19 nontransplant deaths have occurred within 1-11 (median 3) mo of diagnosis. Compared to nontransplant regimens, early transplantation more effectively restores normal marrow function and decreases the acute mortality of severe marrow aplasia (p = 0.006). Pending longer follow-up, early marrow transplantation appears to be the most effective available treatment for severe aplastic anemia.
"Fetal" erythrocytes are present in older children and certain adults with hematologic disorders. To determine if regenerating bone marrow produces such cells, we examined the blood of seven allogeneic bone marrow transplant recipients. Six patients were engrafted with donor cells, while on e patients recovered autologous bone marrow after rejection of a marrow transplant. All seven patients had fetal hemoglobin levels of up to 10% by 100 days after transplant. In three patients, the Ggamma to Agamma ratio in the fetal hemoglobin was "newborn", while in one it was "adult". Gamma chain synthesis in blood and bone marrow never exceeded 20% of total non-alpha globin synthesis. The fetal hemoglobin was heterogeneously distributed in the cells. High titer i antigen also appeared. All fetal characteristics declined by 200 days. Erythropoiesis during bone marrow recovery appears to be associated with an accelerated, albeit partial, recapitulation of ontogeny.
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Despite androgens and intensive supportive care, satisfactory survival in severe aplastic anemia remains at 20% or less. Histocompatible bone marrow transplantation can restore normal hematopoiesis in approximately 40% of similarly severe individuals. Delay of transplantation for 3 wk after diagnosis allows time for proper evaluation and for many spontaneous recoveries. Further delay increases risks of fatal complications and decreases chances for successful transplantation while the incidence of spontaneous remission declines. When available, early histocompatible bone marrow transplantation may be the treatment of choice for severe aplastic anemia.