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Biomedical subjects

D H Pamphilon

Publications and source records attributed to D H Pamphilon.

At least 37 records · Page 2Linked to original sources
PubMed1998

Minimal residual disease status before allogeneic bone marrow transplantation is an important determinant of successful outcome for children and adolescents with acute lymphoblastic leukemia.

The efficacy of allografting in acute lymphoblastic leukemia (ALL) is heavily influenced by remission status at the time of transplant. Using polymerase chain reaction (PCR)-based minimal residual disease (MRD) analysis, we have investigated retrospectively the impact of submicroscopic leukemia on outcome in 64 patients receiving allogeneic bone marrow transplantation (BMT) for childhood ALL. Remission BM specimens were taken 6 to 81 days (median, 23) before transplant. All patients received similar conditioning therapy; 50 received grafts from unrelated donors and 14 from related donors. Nineteen patients were transplanted in first complete remission (CR1) and 45 in second or subsequent CR. MRD was analyzed by PCR of Ig or T-cell receptor delta or gamma rearrangements, electrophoresis, and allele-specific oligoprobing. Samples were rated high-level positive (clonal band evident after electrophoresis; sensitivity 10(-2) to 10(-3)), low-level positive (MRD detected only after oligoprobing; sensitivity 10(-3) to 10(-5)), or negative. Excluding 8 patients transplanted in CR2 for isolated extramedullary relapse (all MRD-), MRD was detected at high level in 12 patients, low level in 11, and was undetectable in 33. Two-year event-free survival for these groups was 0%, 36%, and 73%, respectively (P <.001). Follow-up in patients remaining in continuing remission is 20 to 96 months (median, 35). These results suggest that MRD analysis could be used routinely in this setting. This would allow identification of patients with resistant leukemia (who may benefit from innovative BMT protocols) and of those with more responsive disease (who may be candidates for randomized trials of BMT versus modern intensive relapse chemotherapy).

Adolescent↗
PubMed1998

Second allogeneic bone marrow transplants from unrelated donors for graft failure following initial unrelated donor bone marrow transplantation.

Graft failure is a common and severe complication of unrelated donor bone marrow transplantation (UD-BMT). However, there are few reports of a second UD-BMT in this setting. We describe 12 patients with graft failure (five primary, seven secondary) who had a second transplant, five from their original donor and seven from a different donor. Their median age was 9 years. Two patients died before day 10 of regimen-related toxicity. Nine of 10 evaluable patients engrafted in a median of 17 days. Secondary graft failure was seen in one patient. Transplant-related morbidity was significant. Six of nine developed acute GHVD, there were five severe infections and five patients developed Bearman grade 3 or 4 extramedullary toxicity. Overall, five patients survive at a median of 38 months after the second BMT and two are in continuous complete remission. Second transplants from unrelated donors for graft failure can result in prolonged survival.

Adolescent↗
PubMed1998

Influence of ultraviolet-B irradiation on engraftment, graft-versus-host disease and graft-versus-leukemia effect in a rat model for allogeneic bone marrow transplantation.

Ultraviolet-B (UVB) irradiation is known to inhibit lymphocyte activity and consequently to reduce the incidence of graft-versus-host disease (GVHD) in experimental models for allogeneic bone marrow transplantation (BMT). GVHD is frequently associated with morbidity and mortality, but also with the beneficial graft-versus-leukemia (GVL) effect, demonstrated by a reduction in the incidence of leukemia relapse. In this study, we investigated whether UVB treatment of allogeneic T cells could prevent GVHD while sparing the beneficial GVL effect following allogeneic BMT in the Brown Norway myelocytic leukemia (BNML) rat model analogous to human acute myelocytic leukemia (AML). The dose of UVB required to abolish lethal GVHD in the rat allogeneic BMT model (WAG/Rij donors into BN recipients) was 4000 J/m2. However, this UVB dose simultaneously abrogated all GVL activity mediated by the T cells in the graft, while the radio-protective capacity of rat BM cells was strongly reduced. The number of allogeneic BM cells required to protect lethally irradiated BN rats was increased 50 to 100-fold. It is concluded that UVB acts as a non-selective form of T cell inactivation, and that UVB pretreatment of an allogeneic marrow graft is unlikely to be useful clinically as a preventive measure for GVHD, since other means of reduction of the number of functional T cells are less damaging to bone marrow stem cells.

Animals↗
PubMed1998

Double T cell depletion of bone marrow using sequential positive and negative cell immunoaffinity or CD34+ cell selection followed by Campath-1M; effect on CD34+ cells and progenitor cell recoveries.

An advantage of CD34+ cell selection over antibody purging is that a component allograft is produced comprising a stem cell enriched and an unadsorbed fraction, the latter containing T cells which may be used for post-transplant immunotherapy. Initial reports with PBSC allografts suggested that T cell depletion (TCD) by CD34+ cell selection and post-graft cyclosporin A +/- methotrexate was insufficient prophylaxis against acute GVHD. We compared sequential TCD (of a CD34+ cell-selected fraction) using a second (CD2) immunoaffinity step or Campath-1M monoclonal antibody and complement. Since a high stem cell 'dose' enhances engraftment across HLA barriers and improves overall post-transplant outcome, the recovery of CD34+ cells and progenitors were assessed. Sequential positive (CD34+) and negative (CD2+) immunoaffinity selection resulted in a 3.4 log depletion of T cells as compared to a 4.05 log depletion when CD34+ cell selection was followed by Campath-1M treatment. Recoveries of CD34+ cells, CFU-GM and BFU-E following double depletion using CD34+ cell selection plus CD2+ cell depletion were 28, 25 and 17% as compared to 20, 18 and 16% when CD34+ cells were treated with Campath-1M. The unadsorbed fraction contained 85% of the original T cells, from which donor leukocyte infusions in the range of 10(5) to 10(7) CD3+ cells per kg body weight of the recipient were harvested. Despite the advantages of component allografts, the loss of stem/progenitor cells may restrict sequential TCD steps unless single BM harvests are supplemented and/or replaced with mobilised PBSCs.

Alemtuzumab↗
PubMed1998

The outcome of children requiring admission to an intensive care unit following bone marrow transplantation.

We report the results of a retrospective study of the role of intensive care unit (ICU) admission in the management of 367 children who underwent bone marrow transplantation (BMT) at a tertiary referral institution. 39 patients (11%) required 44 ICU admissions for a median of 6 d. 70% received marrow from unrelated donors, half of which were mismatched; 80% had leukaemia and two-thirds were considered high-risk transplants. Respiratory failure was the major reason for admission to ICU. 75% of admissions required mechanical ventilation (for a median of 5 d) and 20 patients had lung injury as defined by the criteria of the Seattle group. None of 11 patients with proven viral pneumonitis survived (P = 0.06) and only one of 20 patients with lung injury survived (P < 0.01). Six of seven patients with a primary neurological problem survived (P < 0.001); these appear to represent a good outcome group. Age, the presence of graft-versus-host disease, the use of inotropes, isolated renal or hepatic impairment, and paediatric risk of mortality (PRISM) score were not predictive of outcome. In total, 12 patients (27% of admissions) survived and were discharged from hospital 30d or more after admission and eight (18%) survived >6 months. ICU admission can be beneficial to selected children post-BMT but it may be less useful in proven viral pneumonitis. Where mechanical ventilation is required, the duration of this support should be limited unless there is rapid improvement.

Acute Disease↗
PubMed1998

Minimal residual disease status as a predictor of relapse after allogeneic bone marrow transplantation for children with acute lymphoblastic leukaemia.

We have analysed the behaviour of minimal residual disease (MRD) after allogeneic bone marrow transplantation (allo-BMT) in 71 children with acute lymphoblastic leukaemia (ALL). The method relied on PCR of IgH, TCRdelta and/or TCRgamma gene rearrangements followed by electrophoretic size resolution and allele-specific oligoprobing. Patients were similarly conditioned; 55 received marrow from unrelated donors and 16 from related donors. MRD was assessed at various time-points up to 24 months after BMT. Three children were not evaluable due to transplant-related mortality. MRD was detected in 28/32 patients (88%) who relapsed post-BMT; 16 were positive at all times and 12 were initially negative but became positive at a median of 3 months (range 1.5-11) prior to relapse. In contrast, only eight of 36 (22%) patients who remained in continuing complete remission (CCR) (median follow-up 43 months, range 20-94) showed MRD at any time after BMT (P<0.0001). In these eight patients MRD was found up to 9 months after transplant and at low levels (0.01-0.001%). All eight (median follow-up 39 months, range 24-87) had at least two MRD-negative samples tested subsequently and five of the eight had evidence of grade I-II acute graft-versus-host disease (GvHD), raising the possibility of a graft-versus-leukaemia effect. In general, any evidence of MRD after allo-BMT is a poor prognostic sign. However, if immunotherapy were to be targeted towards patients with evidence of persisting MRD after BMT, the method described would expose only a small proportion of patients to unnecessary additional toxicity.

Adolescent↗
PubMed1998

Unrelated donor bone marrow transplantation for children and adolescents with Philadelphia-positive acute lymphoblastic leukemia.

PURPOSE: Few patients with Philadelphia-positive acute lymphoblastic leukemia (Ph-positive ALL) have been cured by chemotherapy alone. Registry figures show that 38% of patients who have a matched-sibling bone marrow transplant (BMT) are disease-free 2 years after transplant, but the majority of patients lack a sibling donor. Most modern ALL protocols recommend unrelated donor (UD) BMT for patients with Ph-positive ALL in first complete remission (CR1), but the outcome of this is unknown. PATIENTS AND METHODS: We report the results of 15 children and adolescents who had a T-cell depleted UD-BMT for Ph-positive ALL. Thirteen of 15 had been previously treated on United Kingdom ALL protocols. Nine were in CR1 and six had more advanced disease. Eleven donor recipient pairs were matched at HLA-A, HLA-B, HLA-DR, and HLA-DQ, and four were mismatched at one or two HLA loci. RESULTS: The incidence of greater than grade I acute and chronic graft-versus-host disease (GVHD) was low (13% and 8%, respectively). Six patients have relapsed and seven patients survive at a median of 21 months post-BMT; six of seven are disease free. All seven survivors are in full-time education or work. The 2-year overall and disease-free survivals are 44% +/- 13% and 37% +/- 13% (+/- SE). None of four patients who had mismatched donors survived, but seven of 11 matched recipients survive (P < .05). CONCLUSION: UD-BMT can produce prolonged disease-free survival in young patients with Ph-positive ALL who otherwise would have an extremely poor outlook.

Adolescent↗
PubMed1997

Platelet production methods in the United Kingdom.

Platelets had traditionally been produced in the United Kingdom (U.K.) either from random donor blood by centrifugation of the platelet rich plasma or by plateletpheresis using various apheresis machines. The proportions of apheresis versus non-apheresis derived platelets varying from centre to centre depending on local policy. The production of platelets from random donor blood is labour intensive and in the late 1980s and early 1990s, biotechnology manufacturers developed newer automated techniques to derive platelets from buffy coats aiming to produce a more standard product and reduce the labour intensity of platelet production. At the same time, apheresis technology has continued to develop with the aim of maximising platelet yields from single donors by yielding 4-6 single unit equivalent of platelets per donor while eliminating the need for further laboratory processing. The trend in some European countries and in North America has been to move away from platelets recovered from whole blood either by buffy coat method or by centrifugation of platelet-rich plasma to plateletpheresis. Intense pressure is being put on blood centres to introduce newer technologies which are inevitably more expensive methods of platelet production. Since 1992, centres in the U.K. have gradually changed their method of platelet production and a survey was conducted to examine the status of platelet production within the U.K. This has shown that many centres are moving away from the production of random donor unit platelets derived by secondary centrifugation of platelet rich plasma (25%) towards buffy-coat derived platelets (45.3%) while plateletpheresis remains fairly static (29.7).

Blood Platelets↗
PubMed1997

Blood centres: the effect of cytokine therapy on transfusion medicine.

Platelet concentrates (PCs) are transfused mainly to patients with haematological disease. World-wide, the use of platelets is still increasing due, in part, to more intensive treatment schedules for such patients. Patients transplanted with cytokine mobilised peripheral blood stem cells (PBSC) have a shortened duration of thrombocytopenia and require fewer platelet transfusions. The principal thrombopoietic cytokine--megakaryocyte growth and differentiation factor (MGDF)--has been identified and is now being evaluated in clinical trials. MGDF treatment is likely to be widely used in patients with haematological malignancies to shorten thrombocytopenia resulting from marrow failure. Platelet transfusions will still be required in patients with malignant disease pre- and early post-treatment before MGDF is effective, and in patients with thrombocytopenia caused by massive blood loss or following major surgery. MGDF will, however, reduce the overall requirement for platelets. Transfusion of blood components is associated with a number of adverse effects including viral transmission. Novel strategies such as photodynamic treatment of blood components may maximise the safety of PCs. Erythropoietin (EPO) is clinically indicated for correction of anaemia in a minority of patients and will not significantly affect the requirement for red cell transfusions.

Cytokines↗
PubMed1997

A laboratory comparison of T cell depletion by CD34+ cell immunoaffinity selection and in vitro Campath-1M treatment: clinical implications for bone marrow transplantation and donor leukocyte therapy.

Donor leukocyte infusions (DLI) have been used effectively to induce remission in patients who relapse after BMT. Using CD34+ cell immunoaffinity enrichment, donor T cells may be captured in the unadsorbed (residual) fraction and we assessed this as a potential source of functional T cells for post-BMT immunotherapy. We extended our study to compare CD34+ cell selection and antibody-mediated cell lysis using Campath-1M and measured T cell-depletion, CD34+ cell recovery and relative progenitor proliferative potential. The recovery of CD3+ cells (responsive to IL-2 or PHA) in the unadsorbed fraction was 84+/-12% (mean+/-s.d.) using a laboratory scale CD34+ cell selection process (CEPRATE LC). The immunoselected (CD34+ cell enriched) product contained 55+/-12% of the starting CD34+ cells (purity, 75+/-6%) with recoveries of 44+/-12% and 42+/-13% for CFU-GM and BFU-E respectively. T cell depletion was 99.8+/-0.2% (FACS) and the frequency of clonable T cells estimated at 1:640 (limiting dilution assay). In comparison, Campath-1M-treated marrow samples gave recoveries of CD34+ cells, CFU-GM and BFU-E of 50+/-7%, 78+/-20% and 79+/-18%, respectively. The frequency of clonable T cells was 1:2700 despite an estimated T cell depletion of 98.4+/-1.9%. Data obtained from four BM harvests processed on the clinical grade CEPRATE SC system was comparable in every respect to the laboratory scale system. The yield of 1259 +/- 222 x 10(6) CD3+ cells in the unadsorbed fraction would allow for multiple graded incremental T cell aliquots for DLI for patients with acute leukaemia.

Alemtuzumab↗
PubMed1997

Unrelated donor bone marrow transplantation in children and young adults with acute myeloid leukaemia in remission.

The role of unrelated donor bone marrow transplantation (UD-BMT) in the management of patients with acute myeloid leukaemia (AML) is uncertain. We describe 18 patients with a median age of 13 years (range 4-31) who received an ex vivo T-cell-depleted UD-BMT for AML (13 in second complete remission (CR2) and five in first complete remission (CR1) with high-risk features). Nine donor recipient pairs were fully matched; eight of these donor-recipient pairs had a single class I HLA mismatch; one patient had both single class I and class II HLA mismatches. Grade II GVHD of the skin occurred in four patients (22%) and limited chronic GVHD in two patients (11%). There have been four deaths: one from relapse and three from infection. With a median follow-up of 27 months, 14 patients survive and the actuarial event-free survival at 2 years is 70 +/- 20% (95% confidence interval). We conclude that unrelated donor BMT can result in prolonged disease-free survival in children and young adults with AML.

Adolescent↗
PubMed1997

Same-day determination of chimaeric status in the immediate period following allogeneic bone marrow transplantation.

The accurate and rapid determination of the origin of haemopoietic cells may provide valuable information as to the aetiology of, and most appropriate therapy for, leucopenia following allogeneic bone marrow or peripheral blood stem cell transplantation. We describe an approach to the analysis of chimaerism post bone marrow transplantation (BMT) based on the immunomagnetic capture of white cells combined with microsatellite polymerase chain reaction (PCR) and resolution of products by polyacrylamide gel electrophoresis (PAGE). This non-isotopic method enables the chimaeric status to be determined from as little as 1.0 ml of profoundly leucopenic peripheral blood (WBC < or =0.1 x 10(9)/l) and has been applicable to all donor/recipient pairs tested so far. Results are available within 6 h of blood sampling and lineage-specific chimaerism is possible. Furthermore, blood transfusions do not interfere with the analysis.

Bone Marrow Transplantation↗
PubMed1997

A prospective randomized study of three types of platelet concentrates in patients with haematological malignancy: corrected platelet count increments and frequency of nonhaemolytic febrile transfusion reactions.

We prospectively randomized 51 patients with haematological malignancy requiring platelet concentrates (PCs) to receive either single donor platelet-pheresis products (SD-PC), PCs made from pooled buffy coats (BC-PC) or pooled units of platelets made by the platelet-rich plasma method (PRP-PC). The leucocyte content of each type of PC was 0.33 (0.03-13.5), 5.68 (0.19-99.0) and 365 (65-910) x 10(6); median (range), respectively; P < 0.0001. All red cell transfusions were leucodepleted by filtration. Statistical comparison of the probability of the occurrence of a nonhaemolytic febrile transfusion reaction (NHFTR) following transfusion of PCs in patients in each group showed a significant decrease for the SD-PC and BC-PC groups (0.031 and 0.038, respectively) when compared with PRP-PC (0.171); P = 0.0001. The actual corrected platelet count increments (CCI) at 1-6 and 18-24 h post-transfusion for all three types of PC did not differ significantly. We conclude that transfusion of PRP-PC is associated with a significant increase in NHFTR.

Adult↗
PubMed1996

Effect of ultraviolet-B light on lymphocyte activity at doses at which normal bone marrow stem cells are preserved.

Ultraviolet B (UVB) light is known to be immunosuppressive, but, probably because of a small UVC component in the emission spectra of some of the UVB lamps used, reports vary on effective dose levels. To prevent potentially lethal graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation, alloreactive donor T-cell activity must be suppressed. In this study, a narrow wavelength UVB lamp (TL01, 312 nm peak emission) was used to determine what doses of UVB were required to abolish rat lymphocyte proliferation while simultaneously preserving rat bone marrow progenitor cell and primitive hematopoietic stem cell viability. Lymphocyte proliferation, as measured by 3H-Thymidine incorporation, in response to lectin stimulation was abolished below detection at doses greater than 3,500 J/m2. When T-cell clonogenicity was measured in a limiting dilution assay, a small fraction (0.6%) was maintained at doses up to 4,000 J/m2. Cytotoxic T-lymphocyte (CTL) activity was reduced after treatment with 4,000 J/m2, but a significant level of cytotoxicity was still maintained. Natural killer cell cytolytic activity was not affected by doses up to 4,000 J/m2. At 4,000 J+m2 there was a 10% survival of colony-forming units-granulocyte-macrophage; a 1% and 4% survival of day-8 and day-12 colony-forming units-spleen, respectively; and 11% survival of marrow repopulating ability cells. Up to 25% of late cobblestone area forming cells (4 to 5 weeks), reflecting the more immature hematopoietic stem cells, were preserved in bone marrow treated with 4,000 J/m2, indicating that early stem cells are less sensitive to UVB damage than are more committed progenitor cells. Thus, a potential therapeutic window was established at approximately 4,000 J/m2 using this light source, whereby the potentially GVHD-inducing T cells were suppressed, but a sufficient proportion of the cells responsible for engraftment was maintained.

Animals↗
PubMed1996

Evaluation of a new, integral, whole blood filter (RS2000) system for prestorage leucodepletion of SAG-M red cells.

Residual donor leucocytes are responsible for many adverse transfusion reactions. Prestorage leucodepletion may ameliorate these effects and enhance product quality. We studied a bottom and top (BAT) system incorporating an integral filter for whole blood leucodepletion. Our evaluation assessed leucodepletion efficiency as well as in vitro SAG-M red cell quality and storage characteristics. Sixty-six units of blood were collected; test units into the Optipac-pLuS system and controls into the standard triple pack configuration. Test units were held for 4-6 h at room temperature (rt) or 12-18 h at 4 degrees C. The mean leucocyte counts for the SAG-M red cells in the quality and storage trial were 0.6 x 10(6) (rt hold), 0.05 x 10(6) (4 degrees C hold) and 2500 x 10(6) (controls). We observed no significant differences between the groups for Na+, ATP, 2,3-DPG, glucose, lactate and pH during the 49 d storage. The control group, however, showed a greater increase in haemolysis and K+ with time. Autologous in vivo 24 h red cell recovery, after 42 d storage, was > 75%. Adjustment of processing parameters in subsequent studies gave leucodepleted SAG-M red cells with minimal cell loss (9.19%) plus acceptable haemoglobin content (46-76 g/U) and haematocrit (54-62%). This system achieved > 3.5 log leucodepletion with all but one unit containing < 1 x 10(6) leucocytes. The product quality is good and the system suitable for routine use in blood centres.

Blood Component Removal↗
PubMed1996

Unrelated donor bone marrow transplantation for children with relapsed acute lymphoblastic leukaemia in second complete remission.

Allogeneic sibling bone marrow transplantation (BMT) is the recommended treatment for relapsed childhood acute lymphoblastic leukaemia (ALL), but appropriate donors are only available in 30% of cases. Unfortunately, BMT from unrelated donors (UD) has been associated with high rates of severe graft-versus-host disease (GvHD) and transplant-related mortality (TRM). In an attempt to improve outcome in UD-BMT we have assessed the impact of T-cell depletion using CAMPATH-1 (anti-CD52) monoclonal antibodies in 50 consecutively referred patients with relapsed ALL in second remission. All were previously treated according to MRC protocols UKALL X and XI, and then given chemotherapy on MRC R1 from relapse until UD-BMT, 19 patients had relapsed on and 31 off therapy. Patients and donors were fully matched at HLA-A, -B, -DR and -DQ loci in 29 cases and mismatched in 21 (four mismatched for more than one antigen). Pre-transplant conditioning comprised CAMPATH-1G, cyclophosphamide and total body irradiation. Bone marrow was T-cell depleted in vitro using CAMPATH-1 antibodies. Additional GvHD prophylaxis consisted of cyclosporin A (42 cases), cyclosporin plus methotrexate (four) or none (four). 47 patients engrafted. The incidence of acute GvHD was very low: two patients with grade II disease in the matched group, four with grade II-IV in the mismatched group. Only four patients have chronic GvHD. The actuarial event-free survival (EFS) at 2 years is 53%, with no significant difference between the matched and mismatched group. Further leukaemic relapse was the most important cause of failure. These results are similar to the most favourable published reports for HLA-matched sibling BMT in relapsed ALL.

Acute Disease↗