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H G Prentice

Publications and source records attributed to H G Prentice.

At least 145 records · Page 8Linked to original sources
PubMed1992

IL-2 infusion abrogates humoral immune responses in humans.

Although IL-2 infusion enhances cell-mediated cytotoxicity in patients with neoplastic disease, administration is paradoxically associated with a modest fall in total serum IgG and an increased risk of infection. We now show that the adverse effects of IL-2 infusion on the humoral immune system are substantial. Although IL-2 induces the B cell growth and differentiating factors IL-4 and IL-6, infusion abrogates primary antibody responses entirely and reduces secondary antibody responses 50-fold following antigen challenge. There is no evidence of the generation of cells with suppressive activity on B cells but IL-2 increases the ratio of circulating virgin:memory cells. These results may help to explain the increased rate of bacterial infection in patients receiving IL-2. As IL-2 plays a central role in the generation of an immune response, the finding that it is also sufficiently immunosuppressive to inhibit primary- and secondary-type antibody responses suggests that exploration of the underlying mechanisms may provide insights into immune system homeostasis and may offer new approaches to therapeutic immunosuppression.

Adolescent↗
PubMed1992

Can lung function measurements be used to predict which patients will be at risk of developing interstitial pneumonitis after bone marrow transplantation?

BACKGROUND: Lung function often deteriorates after bone marrow transplantation for haematological malignancies. Whether pulmonary function measurements are useful for monitoring patients' progress after transplantation and for alerting clinicians to the development of pneumonitis is uncertain. METHODS: Serial pulmonary function measurements were made in 39 patients with a haematological malignancy, and the values from 18 recipients of T cell depleted allogeneic (n = 17) or autologous (n = 1) bone marrow transplants who developed interstitial pneumonitis were compared retrospectively with values from 21 recipients of allogeneic (n = 17) or autologous (n = 4) transplants who did not develop pneumonitis. Lung function was measured at the onset of a further 18 episodes of pneumonitis. RESULTS: Measurements made before transplantation showed no difference in forced expiratory volume in one second (FEV1), transfer factor for carbon monoxide (TLCO), or total lung capacity between the two groups, but the forced vital capacity (FVC) was slightly higher in those who developed pneumonitis (mean (SD)% predicted 104 (12)) than in those who did not (93 (17%)). Six weeks and three months after transplantation all pulmonary function measurements had fallen slightly in both groups but TLCO had fallen considerably more in those who later developed pneumonitis, being 71% (SD 11%) and 77% (7%) of pretransplant values in patients who later developed pneumonitis compared with 109% (38%) and 96% (26%) in those who did not. All lung function measurements were significantly lower at the onset of pneumonitis than three months after transplantation, even in patients with no abnormal signs and a normal chest radiograph. CONCLUSIONS: Serial measurements of gas transfer before and after bone marrow transplantation may be useful for predicting which patients will be at risk of developing pneumonitis and may help to diagnose pneumonitis in breathless patients with no abnormal signs.

Adolescent↗
PubMed1992

Second HLA-identical sibling transplants for leukemia recurrence.

We analysed data from 114 recipients of HLA-identical sibling transplants who relapsed and received a second transplant between 1978 and 1989. Twenty-nine patients had acute lymphoblastic leukemia, 46 acute myeloid leukemia and 39 chronic myelogenous leukemia. Median (range) interval between first and second transplants was 15 (1-80) months. Following the second transplant, graft failure occurred in 2%, acute graft-versus-host disease (GVHD) in 27% and chronic GVHD in 21% of patients at risk. Risks of interstitial pneumonia and hepatic veno-occlusive disease were higher after the second than the first transplant. Two-year probabilities (95% confidence interval) of treatment-related mortality, relapse and leukemia-free survival were 41% (30-53%), 65% (53-75%) and 21% (14-30%), respectively. Leukemia-free survival was 7% (2-19%) among patients relapsing less than 6 months after their first transplant, with high rates of both relapse, 77% (49-92%), and treatment-related mortality 69% (46-85%). In contrast, leukemia-free survival was 28% (19-41%) in those relapsing more than 6 months after the first transplant; in this group the probability of relapse was 59% (45-72%) and treatment-related mortality 30% (20-43%). Factors correlated with better outcome included a diagnosis of chronic myelogenous leukemia, relapse more than 6 months after the first transplant, acute leukemia in remission prior to the second transplant and good performance status.

Adolescent↗
PubMed1991

Possible mechanism of selective killing of myeloid leukemic blast cells by lymphokine-activated killer cells.

Major histocompatibility complex-unrestricted lymphokine-activated killer (LAK) cells have been proposed as therapy for a variety of hematologic malignancies. Because these cells recognize and kill their targets independently of their antigen specific CD3 receptor, it is unclear how they might discriminate between normal and malignant cells. We now propose one such mechanism for the selective killing of myeloid leukemia blasts. While both CD2+ and CD2- activated killer cells may inhibit the clonogenic growth of myeloid leukemia cells, only the CD2+ subset effectively inhibits the growth of normal myeloid (granulocyte-macrophage and granulocyte) progenitors. This difference appears to reflect differential requirements for cell adhesion molecule recognition between normal and malignant progenitor cells. Inhibition of the growth of normal granulocyte-macrophage colonies by CD2+ LAK cells is blocked by antibodies to the CD2-lymphocyte function-associated antigen 3 (LFA-3) (CD58) cell adhesion system. In contrast, these antibodies have no effect on CD2+ LAK-mediated inhibition of malignant cell clonogenic growth. Instead, antibodies to the LFA-1 (CD11a/CD18)-intercellular adhesion molecule 1 (ICAM-1) (CD54) adhesion system reduce inhibition. These differences correspond to differential expression of the CD54 cell adhesion molecule by normal and malignant myeloid progenitor cells because less than 15% of normal CD34 positive cells are CD54+ while greater than 85% of CD34+ acute myeloid leukemia blasts express the CD54 antigen. LFA-3, the ligand for CD2, is strongly expressed by erythrocytes, and these cells competitively inhibit killing of normal but not malignant clonogenic cells in an analogous way to the effects of monoclonal antibody to the CD2-LFA-3 adhesion system. The operation of this effect in vivo may be a basis for selective cytotoxicity by CD2+ LAK against clonogenic myeloid blast cells, and could be exploited further with infusion of appropriate monoclonal antibodies.

Antigens, CD↗
PubMed1991

Homeostatic action of interleukin-4 on endogenous and recombinant interleukin-2-induced activated killer cell function.

Cytokine-secreting, major histocompatibility complex-unrestricted activated killer (AK) cells are toxic to a wide range of virus-infected or malignant target cells and may be generated endogenously, eg, after bone marrow transplantation, or by infusion of cytokines such as recombinant interleukin-2 (rIL-2). Although AK cells secrete cytokines such as gamma-interferon and tumor necrosis factor, which are themselves able to recruit fresh cytokine-secreting AK cells, activation in both settings is short-lived, implying the existence of homeostatic regulatory mechanisms. We now demonstrate one mechanism by which rapid homeostasis is achieved. We show that IL-4 is produced in patients with both endogenously and exogenously generated AK cells. The cytokine was detected in serum after marrow transplantation, and IL-4 transcripts appeared in circulating lymphocytes during rIL-2 infusion. Although IL-4 inhibited the induction phase of AK cell function, it had no significant inhibitory effect on the ability of AK cells from these individuals to respond to restimulation. Nonetheless, neutralization of the IL-4 induced during cell activation doubled the half-life of AK function, once activating stimuli were removed, from 18 to 44 hours and produced a 2-log increase in AK cell secretion of tumor necrosis factor and gamma-interferon. These data suggest that IL-4 induced in vivo during lymphocyte activation abbreviates AK cell responses once the triggering stimuli have been removed. Neutralization of endogenous IL-4 in vivo by appropriate monoclonal antibodies might prolong the duration of AK function.

Bone Marrow Transplantation↗
PubMed1991

Cytomegalovirus excretion after bone marrow transplantation cannot be predicted from the pre-transplant level of IgG antibodies.

The relationship of pre-bone-marrow transplant recipient and donor cytomegalovirus (CMV) antibody level to post-transplant recipient CMV excretion was investigated. CMV excretion was found to be related to pre-transplant recipient serological status, but not to level of antibody. This therefore contrasts with herpes simplex virus (HSV), for which pre-transplant antibody level in recipients predicts post-transplant HSV excretion.

Adolescent↗
PubMed1991

Ewing's sarcoma t(11;22) in a case of acute nonlymphocytic leukemia.

Chromosome analysis of bone marrow cells from a patient with acute nonlymphocytic leukemia M2 revealed the translocation t(11;22)(q24;q12) usually associated with Ewing's sarcoma. Molecular investigations ruled out the possibility that this was a variant Philadelphia translocation with breakpoints in the major breakpoint cluster region. Although cytogenetic analysis was not available at diagnosis, this abnormality was found both pre- and postallogeneic bone marrow transplant.

Adolescent↗
PubMed1991

Liposomal amphotericin B (AmBisome): safety data from a phase II/III clinical trial.

AmBisome is a commercially available preparation of amphotericin B incorporated in small unilamellar liposomes. The analysis of safety data provided in a multicentre compassionate phase II/III study evaluating 133 episodes of therapy with AmBisome in patients with severe underlying disease is very encouraging. Rapid (30-60 min) administration of a high daily dose of AmBisome is feasible without the well known side effects observed with the conventional formulation of amphotericin B (Fungizone). Although eleven of 71 patients with initially normal serum creatinine concentrations showed increased values after AmBisome therapy, 17 patients among 50 with initially high creatinine concentrations recovered normal renal function during AmBisome treatment. Hypokalaemia was observed in 24 episodes of treatment (18%). Increases in serum glutamyl oxaloacetic transaminase and alkaline phosphatase were also quite common in this selected population with severe underlying disease and the contribution of AmBisome to these changes is difficult to establish. AmBisome appears a safe alternative to conventional amphotericin B, and its efficacy should be further investigated.

Adolescent↗
PubMed1991

Interleukin 2 infusion induces haemopoietic growth factors and modifies marrow regeneration after chemotherapy or autologous marrow transplantation.

Administration of interleukin 2 (IL2) to patients with minimal residual malignant disease following myeloablative chemo-radiotherapy may augment immune reconstitution and reduce the risk of relapse by increasing cytotoxic effector function and cytokine dependent killing directed at residual malignant cells. The ability of IL2 generated activated killer cells to inhibit haemopoietic progenitor cells and to release gamma-interferon (gamma IFN) and tumour necrosis factor (TNF) may, however, retard haemopoietic recovery, as both TNF and gamma IFN inhibit normal myelopoiesis in vitro. To determine the effect of IL2 infusion on myeloid regeneration in vivo, we have examined haemopoietic recovery in patients receiving this cytokine following autologous marrow transplantation or ablative chemotherapy. We find that IL2 infusion accelerates neutrophil recovery and that granulocyte-macrophage colony stimulating factor (GMCSF) and IL3 mRNA become detectable in circulating mononuclear cells. Induction of TNF by IL2 may also contribute to subsequent acceleration of myelopoiesis by initiation of GM-CSF mRNA synthesis in patient marrow fibroblasts. These results show that IL2 infusion may facilitate myeloid recovery when administered during the period of haemopoietic regeneration following ablative chemoradiotherapy.

Acute Disease↗
PubMed1991

Blood product support in patients undergoing chemotherapy and autologous or allogeneic bone marrow transplantation for haematological malignancies.

Three groups of patients with leukaemia and myelodysplasia were assessed with regard to the blood product support they required during their period of bone marrow hypoplasia following treatment. One group received myelo-ablative remission-induction chemotherapy followed by appropriate consolidation therapy (two courses in patients with acute myeloid leukaemia and one or two intensification courses in patients with acute lymphoblastic leukaemia); whilst the other two had 'conditioning' with chemotherapy and radiotherapy prior to autologous bone marrow transplantation (auto-BMT) or T cell depleted allogeneic bone marrow transplantation (allo-BMT). There was no statistically significant difference in blood product requirements between the three groups. However, platelet requirements during remission-induction chemotherapy alone were significantly less than for allo-BMT or auto-BMT. Platelet requirements for patients undergoing auto-BMT were also significantly higher than for patients receiving consolidation chemotherapy; and were required for a longer period than for patients receiving allogeneic-BMT. There was no difference in blood product support between ABO matched and mismatched transplants within the allogeneic group, but the presence of graft versus host disease and/or cytomegalovirus infection did significantly increase the requirements for blood product support.

Adolescent↗
PubMed1991

Successful treatment of acute myeloid leukemia beyond first remission with autologous bone marrow transplantation using busulfan/cyclophosphamide and unpurged marrow: the British autograft group experience.

The results in 34 adult patients with acute myeloid leukemia (AML) who have undergone autologous bone marrow transplantation (ABMT) using busulfan and cyclophosphamide (Bu/Cy) in 12 United Kingdom (UK) centers have been analyzed. There were 19 females and 15 males; median age was 40 years (range, 21 to 62 years). Nine patients were in first relapse; 25 were in second remission. The median time of first remission for the whole group was 11.5 months (range, 1 to 56 months). All the patients in first relapse and six patients in second remission received first remission marrow. The leukemia-free survival (LFS) for the patients in first relapse was 33%, with a median follow-up of 20 months. The LFS for the patients in second remission was 48% with a median follow-up of 26 months. The length of second remission exceeds the length of first remission in 14 patients. Considerable toxicity with hemorrhagic cystitis (four patients; none fatal), venoocclusive disease (four patients; one fatal), pneumonitis (four patients; one fatal), intracranial hemorrhage (two patients; two fatal) has occurred. There have been four procedure-related deaths (12%). Hematologic recovery was satisfactory for neutrophils (median time to 0.5 x 10(9)/L, 22 days [range, 11 to 101 days]), but very slow for platelets (median time to 50 x 10(9)/L, 62 days [range, 15 to 1,080 days]). This study suggests that the use of Bu/Cy with ABMT for patients beyond first remission in AML compares favorably with chemotherapy, and although the procedure-related mortality is acceptable, it is associated with protracted platelet recovery.

Acute Disease↗
PubMed1991

IL2 activated killer cells may contribute to cytomegalovirus induced marrow hypoplasia after bone marrow transplantation.

Cytomegalovirus (CMV) infection remains the commonest cause of infective death following allogeneic bone marrow transplantation (BMT). CMV disease post-BMT occurs in the context of compromised cellular defence mechanisms and is associated with marrow hypoplasia and pneumonitis. However, CMV infection induces release of interleukin 2 (IL2) which in turn generates MHC unrestricted lymphokine activated killer (LAK) cells. We have investigated whether recruitment of IL2 activated MHC unrestricted defence mechanisms post-transplant can be implicated in the marrow hypoplasia that frequently accompanies CMV infection. The results show that IL2 activated peripheral blood mononuclear cells (PBMC) have substantial cytotoxicity against MHC matched and MHC mismatched marrow fibroblasts but that this activity is not specific for CMV infected fibroblasts; uninfected target cells are also equally killed. Furthermore, post-BMT PBMC show greater responsiveness to IL2 than normal PBMC in killing of marrow fibroblasts. We provide a hypothesis from these observations which may explain some of the consequences of CMV infection post-BMT. Local production of IL2 activated cytotoxic cells which would be generated during CMV infection would damage uninfected as well as infected marrow fibroblasts and thereby could compromise haemopoietic growth factor production by marrow fibroblasts. Similarly generated cytotoxicity in the lung may accompany CMV pneumonitis. Our results suggest that administration of anti-IL2 receptor antibody may have a therapeutic role in CMV disease post-BMT as has recently been shown in graft-versus-host disease.

Adolescent↗