Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0002874 (aplastic anemia)
 5,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antithymocyte globulin (ATG) is an effective treatment in patients with severe aplastic anemia (SAA). Its mechanism of action remains unclear, although it has been assumed to be immunosuppressive. However, ATG has also been shown by several laboratories to be immunostimulatory. Recently, interleukin-1 (IL-1) production has been found to be decreased in lipopolysaccharide-stimulated peripheral blood monocytes obtained from SAA patients. We have investigated the ability of ATG to function as an immunostimulatory agent via the production of IL-1 and IL-6 by normal human monocytes in vitro. Supernatants from ATG-stimulated monocytes were assayed for biologically active and immunoreactive IL-1 and IL-6. We have found that ATG, via its F(ab')2 fragment is a powerful inducer of IL-1 and IL-6 production. Furthermore, ATG induction of both cytokines from normal monocytes required de novo synthesis, as determined by 35S-methionine incorporation. Because these two cytokines synergize with other cytokines at both the stem cell and progenitor levels, these stimulatory properties of ATG may be relevant to the treatment of SAA. This would favor the hypothesis of a bimodal mechanism for ATG as an inducer of hematopoietic growth factors and as an immunosuppressive agent.
 ...
PMID:Release of interleukin-1 and interleukin-6 from human monocytes by antithymocyte globulin: requirement for de novo synthesis. 142 74

We have reviewed the records of all patients referred to our departments with aplastic anaemia during the 11 years from 1979 to 1989. Of the 22 patients identified, 19 fulfilled the standard criteria for severe aplastic anaemia. There were 11 females and 11 males. Their mean age was 35 (range 2-85 years). Five cases followed exposure to drugs known to cause aplastic anaemia and one had a recent history of viral hepatitis. A variety of treatments were used. Four patients received an allogeneic bone marrow transplant (BMT) from matched sibling donors and two of these were alive and well 65 and 120 months post BMT. Antithymocyte globulin (ATG) treatment has been followed by lasting complete remission in two of the six patients treated and a partial response was seen in one other patient. Cyclosporin therapy was associated with unmaintained complete remission in one of the three patients given this drug after ATG had failed. The remaining 13 patients received only supportive care with or without androgens and six (46%) had early recovery of bone marrow function with lasting complete remission. These patients illustrate some of the therapeutic options available for aplastic anaemia.
 ...
PMID:Aplastic anaemia in Christchurch Hospital 1979-89. 194 72

A total of 15 patients 1 to 16 years of age were treated for aplastic anemia (13 of a severe degree) and followed-up for a mean of 24 months (range 2 to 64 months). Six patients had an HLA-matched sibling and underwent allogeneic bone marrow transplantation. Nine patients who lacked a suitable donor were given immunosuppressive therapy. Antithymocyte globulin was the initial treatment for eight of these nine patients. Two patients who failed to respond to antithymocyte globulin were then treated with cyclosporine A. Pretreatment age, hematologic measurements, duration of follow-up, and interval prior to therapy were similar between the two groups. All of the patients receiving bone marrow transplants had a complete response and now have normal blood cell counts. Six of nine patients (67%) responded to antithymocyte globulin and are now transfusion free, although three have mild thrombocytopenia. Both patients given cyclosporine A had a good response and are also transfusion free. Patients who underwent marrow transplantation had a significantly shorter period of transfusion dependence for RBCs (9 v 4 weeks, P less than .005) and platelets (5 v 21 weeks, P less than .05). The patients given immunosuppressive therapy have significantly lesser platelet counts in follow-up but have similar values for both hemoglobin and absolute granulocyte counts. Although HLA-matched bone marrow transplantation leads to a faster and more complete recovery for children with aplastic anemia, immunosuppressive therapy can provide a good outcome for children with this disorder.
 ...
PMID:Immunosuppressive therapy versus bone marrow transplantation for children with aplastic anemia. 264 21

Antithymocyte globulin (ATG) and antilymphocyte globulin (ALG) are effective therapies in aplastic anemia; their mechanism of action is undefined. We assayed multiple properties of ATG and ALG to address the biological and immunological bases for differences between ATG and ALG and lot variation. In addition, we studied a lot reported to be inactive in an American clinical trial; however in retrospect, this lot appeared to be active in patients treated in Europe. Immunoprecipitation of thymocyte and lymphocyte membrane proteins with ATG and ALG showed between 14 and 18 major bands on SDS-PAGE, but the patterns for ATG and ALG were not identical. The ability of ATG and ALG to block binding of labeled monoclonal antibodies was assessed using flow cytometry and a radioimmunoassay. In general, there was more lot variation among ALGs than ATGs; however, all ALG lots were more potent blockers of binding of anti-HLA-DR and anti-Leu 1 antibodies than was ATG. Both ALG and ATG effectively blocked binding of anti-Leu 2a, anti-Leu 3a, anti-Leu 4, anti-Leu 5b, and anti-IL 2 receptor abs; neither blocked binding of anti-Leu 7. All preparations were capable of inducing T-cell blastogenesis, although there was considerable lot variation. All lots lysed 60% to 75% T cells in a rabbit complement-mediated cytotoxicity assay, with most having a plateau of activity at 5 to 10 ug/mL. Two lots of ALG, including the lot reported to be clinically inactive, showed less toxicity at suboptimal concentrations and did not plateau even at 80 ug/mL. In total, these results indicate important differences between ATG and ALG in general, more lot variation among ALGs than ATGs and only differences in cytotoxicity between an "inactive" lot of ALG and most, but not all, other active ATG and ALG preparations.
 ...
PMID:Biological and immunological characterization of ATG and ALG. 309 Nov 15

Antithymocyte globulin (ATG), a horse antihuman thymus antiserum highly effective in the majority of patients with aplastic anemia, was studied for its in vitro effects on hematopoietic progenitor cells. Marrow cells isolated by an immunoadherence technique with the HPCA-1 (human progenitor cell antigen) monoclonal antibody after removal of contaminating T cells and macrophages formed erythroid colonies in methyl cellulose media in the presence of ATG at concentrations of 25-50 micrograms/ml. ATG also stimulated continuous production of hemoglobin-containing erythroid colonies beyond 35 days of culture when it was added to the culture weekly. ATG also had an indirect effect on myeloid (granulocytic and macrophagic) colony growth in vitro. At a concentration of 10 micrograms/ml, ATG stimulated late but not early myeloid progenitor cells to form mature colonies. This effect required the participation of lymphocytes containing the Leu-11 antigen and macrophages or supernatant fluids made from these two types of cells that had been preincubated with ATG for 3 hr and then cultured for 5 additional days. The supernatant fluids produced in such a manner showed characteristics similar to granulocyte colony-stimulating factor and had an activity peak that eluted at a volume corresponding to a 20,000 Da molecular mass protein by high-resolution liquid chromatography.
 ...
PMID:Antithymocyte globulin stimulates human hematopoietic progenitor cells. 311 77

Three patients who received antithymocyte globulin therapy for severe aplastic anemia due to gold therapy are described. In 2 patients the hemoglobin, white blood cell count and neutrophils were normal and platelet counts exceeded 100 X 10(9)/1 more than 2 years after treatment. The 3rd patient did not respond to antithymocyte globulin or to cyclosporine therapy; subsequent allogeneic bone marrow transplantation resulted in satisfactory engraftment at 12 months. In all 3 patients the arthritis was improved after the episode of marrow aplasia and its treatment. Including these 3 patients, 12 reported patients with severe aplastic anemia due to gold have now been treated with antithymocyte globulin; 8 have shown significant improvement. These results are better than those reported for any other treatment. Antithymocyte globulin may be optimal initial treatment for this serious disorder.
 ...
PMID:Immunosuppression as initial treatment for gold induced aplastic anemia. 312 73

Antithymocyte globulin (ATG) is an established form of therapy for severe aplastic anemia (SAA). However, in patients who do not respond to this treatment and who are not candidates for bone marrow transplantation few successful therapeutic alternatives exist. We report two such patients who have shown a therapeutic response to Cyclosporin A (CSA) (Sandimmune, Sandoz). Case 1, a 15 year old male, and Case 2, a 34 year old female, were diagnosed as having SAA in September 1984 and May 1984 respectively. Treatment with high dose Methylprednisolone (MPN) and ATG in Case 1 and MPN, ATG and Oxymetholone in Case 2 for ten days was ineffective in both cases. Case 1 developed anaphylaxis with both repeat ATG and ALG (antilymphoblast globulin), and Case 2 failed to respond to repeat ATG. Both required frequent packed cells and platelet transfusions. At five and six months respectively following completion of ATG therapy, CSA was started at 10 mg/kg/day in divided doses orally. Renal and liver functions and CSA blood levels were followed. Within six weeks both patients exhibited a hematologic response and were no longer transfusion dependent. On maintenance therapy of 4 mg/kg/day (Case 1) and four months after discontinuing CSA (Case 2) the hematologic values are as follows: hemoglobin 160 and 130 g/L, absolute granulocyte count 3100 and 1640 X 10(9)/L, and platelets 132 and 84 X 10(9)/L respectively. Side effects included hypertrichosis, gingival hyperplasia and mild reversible nephrotoxicity. CSA appears to represent an effective form of therapy for patients with SAA refractory to ATG.
 ...
PMID:Cyclosporin A for the treatment of aplastic anemia refractory to antithymocyte globulin. 363 Oct 63

Antithymocyte globulin (ATG) therapy is an important treatment alternative for patients with acquired aplastic anemia. The mechanism by which it exerts its effects on hematopoiesis is unknown. In this report, we describe the ability of horse ATG to induce growth and differentiation of normal bone marrow. A single cell suspension of normal human bone marrow was cultured in methylcellulose medium and examined for the growth and maturation after incubation with ATG (10 micrograms/ml). After 3-4 days of culture, spherical colonies containing mature myeloid elements were found in cultures containing ATG but not in cultures containing medium or preimmunization horse IgG. The addition of 10% colony-stimulating factor increased growth by 40%. The number of spherical colonies is not dependent on the presence of macrophages or T lymphocytes. This property of ATG may be relevant to the mechanism behind the hematologic recovery in some patients with acquired aplastic anemia. We also describe the ability of ATG to induce terminal differentiation in the HL60 leukemic cell line. ATG binds to HL60 cells and at concentrations between 10 and 100 micrograms/ml, 50% of the cells become mature granulocytes, acquire the ability to reduce nitroblue tetrazolium, and lose their proliferative capacity in the clonogenic assay. These new observations of ATG-induced differentiation of normal marrow myeloid elements and terminal differentiation of the HL60 cell line point to different avenues for future search of differentiation-inducing agents.
 ...
PMID:Differentiation of normal marrow and HL60 cells induced by antithymocyte globulin. 387 92

Antithymocyte globulin (ATG) is frequently effective therapy for aplastic anemia. Its mechanism of action is often assumed to be upon a lymphocyte inhibitor of hematopoiesis. However, specificity for T lymphocytes would not be anticipated from consideration of the method of preparing ATG. In fact, using flow microfluorometry and fluorescence immunohistochemistry, we have found that ATG binds to virtually all circulating lymphocytes, granulocytes, and platelets, as well as to bone marrow cells. Extensive absorption of ATG with either granulocytes or lymphocytes does not eliminate reactivity with the opposite cells, indicating that ATG recognizes some distinct antigens on each cell type. Treatment of cells with ATG blocks the binding of monoclonal antibodies directed against either lymphocyte differentiation or histocompatibility antigens. ATG also binds to visceral tissues, including thymus and testis cell membranes and the nuclear and cytoplasmic components of tonsil, kidney, liver, breast, lung, and intestine. In vitro cytotoxicity of ATG was demonstrated for both T and non- T lymphocytes and platelets. Despite its name, ATG is not specific for a particular cell type, and it would be premature to conclude that its effect is mediated through a specific lymphocyte population.
 ...
PMID:Antithymocyte globulin reacts with many normal human cell types. 635 3

Antithymocyte globulin (ATG) therapy is an established form of treatment for aplastic anaemia and has also been used as prophylaxis against graft rejection of bone marrow and renal allografts. Administration of ATG preparations has been associated with many mild clinical reactions, as have other forms of immunomodulatory therapy. However, serious adverse effects appear to be rare. We report a case of rapidly progressive fibrosing alveolitis and thyrotoxicosis in relation to ATG therapy, highlighting its potential toxicity and emphasising that its administration should be undertaken by experienced physicians in specialised centres.
 ...
PMID:Rapid progression of fibrosing alveolitis and thyrotoxicosis after antithymocyte globulin therapy for aplastic anemia. 763 18


1 2 3 4 Next >>