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Biomedical subjects

A V Hoffbrand

Publications and source records attributed to A V Hoffbrand.

At least 19 recordsLinked to original sources
PubMed1992

Bone marrow transplant recipients have defective MHC-unrestricted cytotoxic responses against cytomegalovirus in comparison with Epstein-Barr virus: the importance of target cell expression of lymphocyte function-associated antigen 1 (LFA1).

Cytomegalovirus (CMV) remains the most common single infective cause of death following allogeneic bone marrow transplantation (BMT) from major histocompatibility complex (MHC)-identical siblings, whereas Epstein-Barr virus (EBV)-related disease is infrequent. We show here that MHC-unrestricted cytotoxic effector cells in the peripheral blood of BMT recipients are highly effective at killing EBV-infected target cells, but are inactive against CMV-infected target cells. Differential cytotoxicity is associated with disparate target structure expression. Although both EBV- and CMV-infected target cells express viral antigens, it is only those infected with EBV that express the adhesion molecule lymphocyte function-associated antigen 1 (LFA1; CD11a/18). Thus, EBV-infected target cells are able to interact with the principal LFA1 ligand, intercellular adhesion molecule 1 (ICAM1; CD54), which is expressed on posttransplant peripheral blood mononuclear (PBM) effector cells. CMV-infected target cells cannot utilize this ligand. Posttransplant cytotoxicity against EBV-infected target cells is abolished by target and effector cell blockade with monoclonal antibodies (MoAbs) to LFA1 and ICAM1, respectively, demonstrating the functional relevance of this additional ligand interaction. These results provide an illustration both of the importance and of the limitations of MHC-unrestricted cytotoxicity in vivo and may explain the frequency of CMV disease and the relative rarity of EBV-related disease following allogeneic transplantation from MHC-matched siblings. The increased immunosuppression used following MHC-mismatched/matched unrelated-donor BMT may cause this MHC-unrestricted defense mechanism to fail and may contribute to the greatly increased incidence of EBV lymphoproliferative syndrome in these patients.

Adolescent↗
PubMed1992

Stomatococcus mucilaginosus: an emerging pathogen in neutropenic patients.

Stomatococcus mucilaginosus was isolated from eight neutropenic patients during nine febrile episodes over a 13-month period. Five of these isolates were from definite infections, including one case of fatal meningitis. This slime-producing, catalase-variable, gram-positive coccus is a component of the normal oral flora of humans. Its biochemical profile may result in misidentification; however, unlike most micrococci, it characteristically fails to grow on media containing 5% NaCl. All but one of our isolates were sensitive to benzylpenicillin, and all were sensitive to vancomycin. S. mucilaginosus may prove to be an important pathogen in severely immunocompromised patients.

Adult↗
PubMed1992

Serum non-transferrin-bound iron in beta-thalassaemia major patients treated with desferrioxamine and L1.

Non-transferrin-bound iron (NTBI) in plasma is toxic due to its ability to participate in free radical formation with resultant peroxidation and damage to cell membranes and other biomolecules. NTBI concentration was determined in serum in 12 normal volunteers and in 52 patients with beta-thalassaemia major by a modification of the method described by Singh et al (1990). There was no detectable NTBI in normal individuals. In the patients NTBI values ranged from -1.5 to 9.0 mumol/l (mean +/- SD: 3.6 +/- 2.3). The patients' serum ferritin concentrations ranged from 207 to 11,400 micrograms/l (2674 +/- 2538), total serum iron from 20 to 61 mumol/l (39.5 +/- 9.6) and transferrin saturation from 44 to 110% (84.5 +/- 13.8). The NTBI correlated significantly with serum ferritin (r = 0.467, P < 0.001), total serum iron (r = 0.608, P < 0.001) and transferrin saturation (r = 0.481, P < 0.005). When patients were grouped according to their compliance with desferrioxamine (DFX) therapy, the good compliers had significantly lower NTBI concentrations compared to the poor compliers (poor: 5.4 +/- 1.8 mumol/l v good: 2.7 +/- 1.7 mumol/l, P < 0.001). There was also a significant difference between the level of NTBI and whether or not the patients had complications of iron overload (5.2 +/- 1.7 mumol/l v 2.9 +/- 1.6 mumol/l, P < 0.001). During this study 10 patients were entered into a trial of the oral iron chelator 1,2- dimethyl-3-hydroxypyrid-4-one (L1). Their NTBI values were observed during the first 6 months of the trial and showed a significant fall (paired t-test: P = 0.007). These results suggest that the level of NTBI may prove helpful in assessing the efficiency of chelation in patients with transfusion dependent anaemia and help to predict organ damage.

Adolescent↗
PubMed1992

Effects of anti-TNF monoclonal antibody infusion in patients with hairy cell leukaemia.

Tumour necrosis factor (TNF) can act as an autocrine growth factor for hairy cell leukaemia (HCL) cells. The TNF produced by the malignant clone may also inhibit normal haematopoiesis thereby contributing to the cytopenias observed in patients with the disease. We have studied the effects of infusing a murine monoclonal anti-TNF antibody in three patients with HCL. In two patients receiving 0.5 mg of antibody/kg on alternate days for 12 d, the drug was well tolerated. The third patient received 2 mg/kg on alternate days and developed symptoms of serum sickness by day 9. In two patients with severe B-lymphocytopenia, circulating CD19 and CD20 positive, B-cells were restored to normal, the majority of which were negative for the HCL-associated marker CD11c. B-lymphocyte recovery was associated with a rise in serum immunoreactive IL-6 and with an early rise in immunoreactive TNF. These short courses of anti-TNF MAb treatment had modest effect on the tumour burden, producing a reduction in splenomegaly in one patient. Exploration of the effects of more prolonged administration of higher dose anti-TNF antibody will only be feasible when less immunogenic MAbs are available.

Animals↗
PubMed1992

Increase in 2',5'-oligoadenylate synthetase caused by deoxycoformycin in hairy cell leukaemia.

2',5'-oligoadenylate synthetase (2-5OAS) has been studied in peripheral blood mononuclear cells from nine patients with hairy cell leukaemia (HCL) receiving therapy with the adenosine deaminase inhibitor deoxycoformycin (dCF) or alpha interferon (alpha-IFN). 2-5OAS mRNA was assayed by dot-blot hybridization. Increase of 2-5OAS mRNA level was seen in six patients with HCL treated with dCF and in one patient treated with alpha-IFN who responded to therapy. A patient with a variant form of HCL treated with dCF and the second patient treated with alpha-IFN did not show an increase of 2-5OAS mRNA and neither responded to therapy. The 15 other patients with T or B-chronic lymphoblastic leukaemia (CLL), T-acute lymphoblastic leukaemia (ALL), adult T-cell leukaemia lymphoma (ATLL), non-Hodgkins lymphoma (NHL), Sezary and T or B-prolymphocytic leukaemia (PLL) treated with dCF did not show an increase in 2-5OAS, though four patients, all with T-cell tumours, responded clinically. 2-5OAS activity is known to be stimulated by alpha-IFN and recent work suggests that this rise in 2-5OAS may result in increased cleavage of mRNA for tumour necrosis factor (TNF) and other cytokines on which autocrine growth and proliferation of the tumour cells are dependent. By analogy, we suggest that one mechanism of action of dCF in hairy cell leukaemia may be to break down an autocrine growth loop for TNF or other cytokines. An alternative explanation for these observations is that cytokines released from hairy cells in the bone marrow killed by dCF induce a rise in 2-5OAS in circulating leucocytes.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Clinical experience of clozapine-induced neutropenia in the UK. Laboratory investigation using liquid culture systems and immunofluorocytometry.

An incidence of drug-induced neutropenia of 2.5% has been found in the first 1000 patients to be treated with clozapine in the UK. The majority of affected patients experienced mild neutropenia (n = 22) with only 3 patients developing agranulocytosis. Data collected from these 25 patients suggest that the mechanism of neutropenia may be multifactorial. Laboratory investigation using liquid culture systems and immunofluorocytometry has identified clozapine and its major metabolite N-desmethyl clozapine as exhibiting toxic effects against myeloid maturation and myeloid mitotic compartments, respectively. Increased susceptibility to the toxic effects of clozapine was shown in 1 patient who had previously developed clozapine-associated neutropenia. No clinical or laboratory evidence of drug-induced antineutrophil or antimyeloid precursor antibodies was found.

Bone Marrow↗
PubMed1992

Effects of interferon-alpha (IFN) on the expression of interleukin 1-beta (IL-1), interleukin 6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF) in acute myeloid leukemia (AML) blasts.

Interferon-alpha (IFN) induces the enzyme 2-5 oligoadenylate synthetase (2-5 AS) in cells from patients with hairy cell leukemia and B-cell chronic lymphocytic leukemia and this is associated with a breakdown of certain species of cytokine messenger (m)RNA via the activation of a latent ribonuclease. We have studied the expression of the cytokines interleukin 1-beta (IL-1), interleukin 6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumour necrosis factor alpha (TNF) as well as of the ribonuclease activator 2-5 AS in the presence and absence of IFN in acute myeloid leukaemia (AML) blast cells from 26 patients. Before monocyte and T-cell depletion there was no expression of IL-1, IL-6 or GM-CSF, and only three of 13 patients studied expressed TNF mRNA. After cell depletion one or more cytokine was expressed in 31-62% of the 26 patients. Expression of one or more mRNA for IL-1, IL-6, GM-CSF and TNF after 18 h incubation was detected in 16 of 26 patients (63%) and this was particularly so in French-American-British (FAB) subtypes M4 and M5. Eight of nine patients with IL-6 mRNA expression and seven of 10 with IL-1 mRNA expression were in the FAB subtypes M4 and M5. Twenty-two of 26 patients showed induction of 2-5 AS mRNA in response to IFN in vitro. Exposure to IFN resulted in reduction of IL-1 mRNA in nine of 12 cases, of IL-6 mRNA in eight of nine, and GM-CSF mRNA in five of seven cases. TNF mRNA was unaffected by IFN despite 2-5 AS induction in 12 of 13 patients expressing this cytokine. In the presence of exogenous IFN, cells from six of seven patients studied showed inhibition of 3H-thymidine incorporation into DNA. DNA synthesis could also be abrogated in six of seven patients with anti-IL-1 monoclonal antibodies (MoAb) and in two of seven with anti-IL-6 MoAb. This inhibitory effect could be reversed in all patients when anti-IL-1 or anti-IL-6 was given in combination with their corresponding cytokine. These data suggest that IFN may exert a therapeutic effect in a proportion of AML patients by blocking IL-1 and IL-6 mediated growth, consequent on activation of the ribonuclease activator 2-5 AS.

2',5'-Oligoadenylate Synthetase↗
PubMed1979

Parenteral acyclovir therapy for herpesvirus infections in man.

Acyclovir is a new antiviral agent which is highly active against herpesviruses in vitro and in laboratory animals. Twenty-three cancer patients with cutaneous and/or systemic herpes zoster or herpes simplex infections were treated with parenteral acyclovir. All had received previous specific treatment for their malignant disease and ten had undergone bone-marrow transplantation. The drug seemed to arrest the progress of the infections and was most effective when given early. Although two patients showed transient increases in blood-urea, possibly the result of acyclovir, the drug was remarkably non-toxic in the doses used.

Adolescent↗
PubMed1979

Defective DNA synthesis in megaloblastic anaemia. Studies employing velocity sedimentation in alkaline sucrose gradients.

1. Autoradiographic experiments revealed that the average size of the replicating unit (replicon) in human phytohaemagglutunin-stimulated lymphocytes is 45 (+/- 1.3) micron. 2. A 5 min pulse of [3H]thymidine labelled DNA chains of approximately 40 S (15 micron) in control lymphocytes as revealed by velocity sedimentation in alkaline sucrose density gradients. Upon chasing in the absence of [3H]-thymidine the labelled DNA increased in size. By 6 h the bulk of the label co-sedimented with full-sized chromosomal DNA. 3. In untreated lymphocytes from patients with megaloblastic anaemia due to vitamin B-12 or folate deficiency or lymphocytes treated with methotrexate (10(-5) M) or hydroxyurea (5 . 10(-4) M) the increase in size of pulse-labelled DNA was slower than in control cells. 4. The block in maturation of pulse-labelled DNA to bulk DNA was not permanent. At 24 h of chase 75-80% of the pulse-label in both control and megaloblastic lymphocytes co-sedimented with bulk DNA. 5. We conclude that the lesions seen in DNA synthesis in megaloblastic anaemia due to folate or vitamin B-12 deficiencies occur through impaired biosynthesis of nucleotide precursors of DNA. Possible explanations of why the defects in DNA synthesis cause altered morphology of proliferating cells in megaloblastic anaemia are suggested.

Anemia, Macrocytic↗
PubMed1979

Improvement in iron status and liver function in patients with transfusional iron overload with long-term subcutaneous desferrioxamine.

Subcutaneous desferrioxamine (2--4 g over 12 h) was administered 6 nights each week to 34 patients with transfusional iron overloads who continued to receive regular blood-transfusions. All 34 patients showed a fall in serum-ferritin after 5 to 12 months. In some patients serum-ferritin fell almost to normal. Liver function improved in all the patients, serum-aspartate-transaminase levels fell in all 17 patients tested, and liver-iron fell in 5 of 6 patients tested. These studies show that body-iron stores can be substantially reduced, to normal or near normal levels, by long-term subcutaneous desferrioxamine in patients with transfusional iron overload despite the need for continued blood-transfusion. They also show that removal of iron is accompanied by improved organ function.

Adolescent↗
PubMed1979

Relation of "lymphoid" phenotype and response to chemotherapy incorporating vincristine-prednisolone in the acute phase of Ph1 positive leukemia.

Forty-four patients with Ph positive leukemia (36 developing blast crisis after chronic phase and eight presenting in acute leukemia) were classified into subgroups on the basis of reactivity of blasts with an anti-serum made against non-T,non-B acute lymphoid leukemia (ALL+), levels of terminal transferase enzyme (TdT+) and morphology. Positivity with anti-ALL serum was the most sensitive and reliable marker, and TdT was an important aid. The presence of "lymphoid" blasts in blast crisis of CML was related to the response to chemotherapy incorporating Vincristine and Prednisolone (VP). Patients with ALL+ blasts frequently (14 of 15 cases) responded to therapy while 21 of 25 patients who had no ALL+ blasts failed to respond. The clinical course of the ALL+ patients was variable: eight patients remitted with return to the appearances of the chronic phase; four patients demonstrated elimination of the Ph1 positive clone with hypoplasia and this was followed by normal (Ph1 negative) marrow regeneration in two. Subsequent relapse was of either the ALL+ "lymphoid" or the ALL-myeloid type. A regimen incorporating VP should be the treatment of choice in "lymphoid" blast crisis of CML.

Antigens, Neoplasm↗
PubMed1979

Terminal deoxynucleotidyl transferase activity in lymphoma.

Terminal deoxynucleotidyl transferase (TdT) was estimated in the tissues of 42 patients with lymphoma, whose cells were also typed by the use of surface markers. Four of the 8 patients with T-cell lymphoma were TdT+ including patients whose lymph nodes showed an undifferentiated or poorly differentiated appearance. The TdT- T-cell lymphomas included cases with diffuse histiocytic Sezary cell, diffuse, poorly differentiated and angio-immunoblastic histology. The tissues of 31 patients with B-cell lymphoma were invariably TdT-, whether the histology was poorly differentiated, well differentiated, nodular, diffuse, histiocytic or Burkitt type, and including cases with about equal proportions of T and B cells, and those whose cells showed non-capping and capping surface immunoglobulin. Hodgkin's tissue was also invariably TdT-. We conclude that estimation of TdT in tissues of patients with malignant lymphoma may be a useful test in diagnosing the T-cell lymphoma, particularly in patients with tumours of undifferentiated or poorly differentiated histology.

Adult↗
PubMed1979

Haem synthesis in sideroblastic anaemia.

Measurement of delta-aminolaevulinic acid (ALA) synthetase has been performed in bone marrow of 24 normal subjects and 20 patients with sideroblastic anaemia (five congenital, two pyridoxine-responsive, 12 primary acquired and one secondary form due to isoniazid therapy). ALA-synthetase activity without added pyridoxal-phosphate in vitro was decreased in four of the congenital cases, and in all 12 primary acquired cases. In two of these 16 cases with low ALA-synthetase activity and in a case with sideroblastic change secondary to isoniazid therapy, the enzyme activity was corrected to normal by pyridoxal-phosphate in vitro. ALA-synthetase activity was normal in both cases of pyridoxine-responsive anaemia while they were receiving pyridoxine therapy but in one of these cases, studied at repeated intervals after withdrawal of pyridoxine therapy, the bone marrow ALA-synthetase activity fell to very low levels unless pyridoxal-phosphate was added in vitro. In this case the Km of the enzyme for pyridoxal-phosphate was substantially greater than that of a control sample. Haem synthetase activity was reduced in the bone marrow of two of six cases of primary acquired sideroblastic anaemia and in one congenital case tested but was normal in the pyridoxine-responsive patient studied on pyridoxine therapy. Nevertheless, this patient showed reduced incorporation of 14C-labelled delta-aminolaevulinic acid into bone marrow haem. It is concluded that both congenital and primary acquired sideroblastic anaemia are a heterogenous group of disorders, with different defects in haem synthesis, reduced activity of delta-aminolaevulinic acid synthetase being common but not invariable in both types. Pyridoxine-responsive (congenital) sideroblastic anaemia may be due to the presence of an abnormal ALA-synthetase apoenzyme which requires excessive amounts of the coenzyme, pyridoxal-phosphate, to achieve normal activity; other abnormalities of haem synthesis may also be present.

5-Aminolevulinate Synthetase↗
PubMed1979

Stimulation of human haemopoietic cells by colony stimulating factors: sensitivity of leukaemia cells.

The sensitivity of populations of human granulocyte precursors to factors with colony stimulating activity (CSA) was assessed in agar culture in vitro. The mean threshold of stimulation was estimated by analysis of dose-response curves of clone growth against concentration of CSA. This method of assessment has the advantage that CSA production by cells contaminating the population under test does not affect results. Marrow cells from patients with acute myeloid leukaemia were less sensitive to CSA than marrow cells from normal individuals. Sensitivities of cells from chronic granulocytic leukaemia and from chronic myelomonocytic leukaemia were within the normal range, but this group also tended to require more CSA than controls. In addition, sensitivities of granulocyte precursors from patients with acute myeloid leukemia were closely related to the culture pattern, and thus to the remission probability. The significance of this relationship is discussed.

Adolescent↗
PubMed1979

Response of neutropenia and anaemia to immunosuppressive therapy: report and bone marrow culture studies.

Soft agar culture of bone marrow cells was used to investigate abnormalities of granulopoiesis in a patient with acquired anaemia and neutropenia which responded to immunosuppressive therapy. Results showed that the patient's peripheral blood leucocytes inhibited granulopoiesis in vitro. Variation in the response of different target marrows suggested that inhibition was not due to direct action on granulocyte-monocyte committed stem cells but was directed against or mediated through the cells in target marrow samples which produce granulopoietic stimulators. Cell separation showed that the inhibitory activity was associated with the patient's mononuclear cells rather than neutrophils. A tentative explanation of the mechanism of production of the anaemia is also offered.

Agranulocytosis↗
PubMed1979

Platelet function in beta-thalassaemia major.

Abnormal platelet aggregation was found in eight (44%) of 18 patients with beta-thalassaemia major and transfusional iron overload. The aggregation defect bore no correlation with the degree of hepatic fibrosis, liver function tests, whether or not splenectomy had been performed, the degree of iron overload, haematocrit, platelet count, serum vitamin E level, or leucocyte ascorbate concentration. Only three of the 18 patients showed prolonged bleeding times as well as abnormal platelet aggregation, and only one of these suffered clinically significant haemorrhage. The results show that a proportion of patients with beta-thalassaemia major have abnormal platelet function. It is possible, however, that the in vitro abnormality might be due partly to artefacts induced by manipulations required to remove the abnormal thalassaemic red cells, and this may explain the much lower incidence of significant haemorrhage.

Adolescent↗