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Biomedical subjects

D H Pamphilon

Publications and source records attributed to D H Pamphilon.

At least 55 records · Page 3Linked to original sources
PubMed1995

Human Rh D monoclonal antibodies (BRAD-3 and BRAD-5) cause accelerated clearance of Rh D+ red blood cells and suppression of Rh D immunization in Rh D- volunteers.

The use of prophylactic anti-D to prevent Rh D immunization in Rh D- women and subsequent hemolytic disease in Rh D+ infants is widespread, but has led to shortages of the anti-D Ig. With the aim of substituting monoclonal anti-D for Rh D prophylaxis, we have compared the abilities of monoclonal and polyclonal anti-D to clear Rh D+ red blood cells (RBCs) infused into Rh D- male volunteers and to suppress Rh D immunization. Two human monoclonal antibodies (MoAbs), BRAD-3 (IgG3) and BRAD-5 (IgG1), produced from stable Epstein-Barr virus-transformed B-lymphoblastoid cell lines, were selected because of their proven in vitro activity in promoting RBC lysis in antibody-dependent cell-mediated cytotoxicity assays. RBC clearance was assessed by intravenous injection of 3 mL of 51chromium-labeled D+ RBCs into 27 volunteers 48 hours after intramuscular injection of monoclonal or polyclonal anti-D. Further 3-mL injections of unlabeled D+ cells were administered at 6 and 9 months to induce immunization. Blood samples were taken throughout the 12-month period of study for the serologic detection of anti-D. The mean half-life (t50%) of RBCs in 7 recipients of 300 micrograms BRAD-5 (5.9 hours) was similar to that in 8 recipients of 500 IU polyclonal anti-D (5.0 hours), whereas D+ cells were cleared more slowly in some of the 8 subjects injected with 300 micrograms BRAD-3 (mean t50% 12.7 hours) and in 1 individual administered 100 micrograms BRAD-3 (t50% 41.0 hours). The rate of RBC clearance in both groups administered 300 micrograms monoclonal anti-D correlated with the amount of antibody bound per cell, determined by flow cytometry. There was no evidence of primary immunization having occurred in any subject after 6 months of follow-up. Five of 24 subjects produced anti-D after one or two further injections of RBCs, confirming that they were responders who had been protected by the monoclonal or polyclonal anti-D administered initially. Four of these responders were recipients of monoclonal anti-D (3 BRAD-3, 1 BRAD-5). One individual who received BRAD-5 produced accelerated clearance of D+ RBCs at the third unprotected RBC challenge but did not seroconvert. This study shows that the human MoAbs BRAD-3 and BRAD-5 can prevent Rh D immunization, and indicates that they may be suitable replacements for the polyclonal anti-D presently used in prophylaxis of Rh D hemolytic disease of the newborn.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1995

Prestorage white cell reduction in saline-adenine-glucose-mannitol red cells by use of an integral filter: evaluation of storage values and invivo recovery.

BACKGROUND: Prestorage white cell (WBC) reduction in blood components may decrease the incidence of adverse reactions and improve component quality. A bottom-and-top system with an integral third-generation WBC-reduction filter has been studied. STUDY DESIGN AND METHODS: Whole blood was collected from 30 healthy donors: from 20 by using a blood container system with an integral filter and from 10 controls by using a standard blood container system. Ten test units were buffy coat-depleted, stored for 72 hours at 4 degrees C, and then filtered, while an additional 10 test units were buffy coat-depleted and filtered at room temperature within 8 hours of collection. All units were stored at 4 degrees C for 42 days and sampled weekly. RESULTS: The mean WBC content of the 72-hour, 4 degrees C units was 0.33 x 10(6), that of the room-temperature units was 2.6 x 10(6), and that of the buffy coat-depleted controls was 460 x 10(6) (p < 0.0005). No significant differences were found among lactate, glucose, sodium, potassium, and plasma hemoglobin levels in the three groups. ATP and 2,3 DPG levels were significantly better preserved in control units than in 72-hour, 4 degrees C units (p = 0.016 and p = 0.032, respectively), but not better than in the room-temperature units. Significant differences were observed between pH values in filtered units and both groups of test units (p = 0.016). In biologic terms however, these differences were small. Red cells from an additional eight healthy volunteer donors were processed by an 8-hour room-temperature method and stored for 35 days. Studies in vivo 24-hour recovery of autologous red cells were performed by transfusing a radiolabeled (51Cr plus 131I-albumin) aliquot after 35 days' storage. Good recovery (mean > 80%) was found by both the single- and double-isotope-label methods. Recovery was significantly greater when calculated by the single-isotope method (p = 0.02). CONCLUSION: The combination of buffy coat removal and filtration in the blood container system with an integral filter achieved effective WBC reduction (> or = 3 log10 reduction from whole blood) without biologically significant detriment to in vitro or in vivo storage values.

Adenine↗
PubMed1995

In vitro demonstration of a fundamental difference in the proliferation of murine and human bone marrow and lymphocytes following ultraviolet irradiation: relevance to bone marrow transplantation.

Exposure of rodent allogeneic donor marrow and splenocyte grafts to ultraviolet radiation (UVR) has been shown to permit durable engraftment at doses that abolish graft-versus-host disease (GVHD) and graft rejection. We have compared both murine and human alloreactive and mitogen-induced lymphoid responses and bone marrow proliferation in mixed lymphocyte culture (MLC), phytohemagglutinin (PHA)-induced proliferation and colony-forming unit-granulocyte/macrophage (CFU-GM) assays using germicidal UVC (200-290 nm), broadband and narrowband UVB (290-320 nm) and UVA (320-400 nm) sources. Our data show a wavelength and dose-dependent reduction in lymphoid proliferation in the mouse with CFU-GM survival of 50-75% of control at doses required to abolish allogeneic lymphocyte responses for all lamps. In contrast, human lymphocyte responses are more resistant to UVC with CFU-GM proliferation reduced to zero when allostimulation is abolished. Mitogen-induced lymphoid responses show a similar wavelength-dependent sensitivity. Abolition of response in MLC using UV-irradiated stimulator cells was less sensitive than proliferation with UV-irradiated responder cells at all wavelengths in both species. With all sources, murine CFU-GM proliferation is less susceptible to UVR than human marrow at doses required to abolish lymphoid responses.

Animals↗
PubMed1994

Randomised trial of intravenous immunoglobulin as prophylaxis against infection in plateau-phase multiple myeloma. The UK Group for Immunoglobulin Replacement Therapy in Multiple Myeloma.

Patients with plateau-phase multiple myeloma have an increased risk of life-threatening bacterial infections and polyclonal humoral immune suppression. We conducted a randomised, double-blind, placebo-controlled, multicentre trial of intravenous immunoglobulin (IVIg) as prophylaxis against infection. 82 patients with stable multiple myeloma received monthly infusions of IVIg at 0.4 g/kg body weight or an equivalent volume of placebo (0.4% albumin) intravenously for 1 year. Other interventions, including chemotherapy, were not affected; no patient received prophylactic antibiotics. There were no differences at entry or on study in clinical or laboratory variables between patients in the two groups. There were no episodes of septicaemia or pneumonia in patients receiving IVIg compared with 10 in placebo patients (p = 0.002). There were 57 serious infections; 38 occurred in 470 patient-months on placebo, compared with 19 in 449 patient-months on IVIg (p = 0.019). IVIg also protected against recurrent infections (p = 0.021) in 60 patients who completed a year. Before treatment, 54 patients were immunised with Pneumovax and specific IgG responses were measured. A poor pneumococcal IgG antibody response (less than 2-fold increase) identified patients who had maximum benefit from IVIg. Mild adverse reactions were noted in 12% of IVIg infusions and 5% of placebo infusions. IVIg can be given safely to plateau-phase myeloma patients. It protects against life-threatening infections and significantly reduces the risk of recurrent infections. The individuals who benefit most can be identified prospectively by measuring IgG antibody responses to pneumococcal immunisation.

Aged↗
PubMed1994

Ultraviolet irradiation for the prevention of graft-versus-host disease and graft rejection in bone marrow transplantation.

This review describes an approach to the prevention of graft-versus-host disease (GVHD) and graft rejection following allogeneic BMT that differs from conventional methods. Ultraviolet (UV) irradiation inhibits the proliferative responses of lymphoid cells to mitogens and alloantigens by inactivation of T lymphocytes and dendritic cells, and in animal models this can prevent both GVHD and graft rejection. It is important that the marrow repopulating capacity of haemopoietic stem cells is not damaged by the irradiation process. We have found that polymorphic microsatellite markers are a sensitive way of assessing the impact of UV irradiation on chimerism after BMT in rodents.

Antigen-Presenting Cells↗
PubMed1993

Quality of platelet concentrates irradiated with UVB light: effect of UV dose and dose rate on glycocalicin release and correlation with other markers of the platelet storage lesion.

The amount of membrane-associated glycoprotein Ib in platelet concentrates (PCs) irradiated with a high dose of UVB light has been shown to be significantly reduced after 48 h storage. We recently corroborated this finding when we noted an increase in the supernatant levels of glycocalicin (GC, a major segment of glycoprotein Ib) in UVB-treated PCs during storage. The aim of the present study was to determine whether GC release was related to both the UV dose and the rate of dose delivery. Plateletpheresis concentrates obtained from five donors were pooled and split into five equal parts. Four of these were treated with 7500 and 15,000 mJ/cm2 UVB using two prototype UV sources with differing rates of dose delivery; namely, Baxter (BAT) and British Aerospace (BAC) cabinets, with the latter having the slower rate of delivery. On days 1 and 5 of storage, GC levels in the supernatants of PCs were determined by ELISA. Moreover, the following parameters were also assessed: platelet and WBC count; hypotonic shock response (HSR) and platelet aggregation response to ADP, ADP+collagen, ADP+arachidonic acid and ristocetin; pH; supernatant levels of lactate, glucose, von Willebrand factor (vWf) and beta-thromboglobulin (beta TG). The results revealed an association of GC release with UVB dose using both UV sources, although this was more apparent in the BAC system, in which glycocalicin release at day 5 of storage was as follows (microgram/ml, mean +/- SD): 4.8 +/- 0.3 and 9.5 +/- 3.6 at 7500 and 15,000 mJ/cm2 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1993

Antibodies to platelet glycoprotein V in polytransfused patients with haematological disease.

Polytransfused patients often develop platelet-reactive antibodies (PRAb). These give positive reactions in the platelet immunofluorescence test (PIFT) and may be either lymphocytotoxic (LCTAb) or platelet-specific antibodies (PSAb). The latter may be detected in the PIFT using chloroquine-treated platelets (Chl-PIFT) or by immunoblotting. Serial samples from 106 multiply transfused patients with bone marrow failure were screened by PIFT using a microplate method and flow-cytometric analysis. PSAb activity was confirmed by Chl-PIFT. In 45 (42%) of the patients studied PSAb were detected; 37 (35%) formed LCTAb and 19 (51%) had co-existent PSAb. Sera from 25 of 27 patients with a positive Chl-PIFT, retested by immunoblotting, recognised determinants of Mr 82-160 kD on whole platelets. A large group became sensitised to a component of Mr 105-115 kD reduced (99 kD non-reduced) with similar electrophoretic mobility to GPIIIa using a monoclonal anti-GPIIIa and two human polyclonal anti-HPA-1a sera; some also produced anti-GPIIb. The largest group recognised a determinant of Mr 80-83 kD, probably glycoprotein V (GPV). Three sera were immunoblotted against thrombin-treated platelets and the results confirmed GPV specificity.

Adolescent↗
PubMed1993

Immune reconstitution after BMT in children.

Serial assessment of peripheral blood T and B cell recovery and serum immunoglobulins was performed in 19 children for the first year following BMT and compared with normal values established from healthy children. Immunophenotypic analysis on bone marrow was performed in selected cases by Southern blotting of the immunoglobulin heavy chain (IgH) gene. We found no significant differences between T cell-replete or depleted allogeneic bone marrow transplants. Lymphocyte numbers were low until 9 months post-BMT. T cell numbers (CD2, CD3, CD5) were also low until 12 months but B cell numbers (CD19) became normal at 3 months. Both CD4+ and CD8+ T cell subsets were low post-BMT with depression of CD4+ greater and more prolonged than that of CD8+. No overshoot of CD8+ was seen. The principal effect of GVHD or its treatment was further depression of CD4+ cells but with no increase in CD8+; recovery of B cells was also delayed. Recovery of IgG was slow with only six of 11 children reaching an age-adjusted normal level by 1 year, whereas there was more rapid recovery of IgM and IgA. Several children had an increase in lymphocytes of immature appearance in their bone marrow at varying times post-BMT with increased cells of phenotype CD19+, CD10+, HLA-DR+ and TdT+. In each case Southern blotting showed a germline pattern of the IgH indicating a polyclonal early B cell regenerative population.

Adolescent↗
PubMed1993

Successful second unrelated donor BMT in a child with juvenile chronic myeloid leukaemia: documentation of chimaerism using the polymerase chain reaction.

A 3-year old child with juvenile chronic myeloid leukaemia received a T cell-depleted BMT from a male unrelated donor. There was early graft failure associated with increasing splenomegaly and hypersplenism. Splenectomy was performed 53 days post-transplant and was followed by autologous marrow recovery with return of leukaemia. A second unrelated donor BMT was performed 9 months later using T cell-replete marrow from a similarly matched female donor. Grade 2 GVHD involving the skin and gut responded to treatment with steroids. Chimaerism was assessed using Y-specific polymerase chain reaction (PCR) and microsatellites. Samples taken at the time of splenectomy showed no donor marrow engraftment but there was significant engraftment in the spleen. Following the second transplant, donor-type haematopoiesis was documented using a panel of microsatellite probes. The patient remains well 6 months after transplant. Splenectomy should be considered prior to transplant in patients with significant splenomegaly and hypersplenism. Partial chimaerism in the spleen, but not bone marrow, post-BMT, has not previously been documented. PCR technology is a useful and highly sensitive way to assess chimaerism post-BMT and is informative in sex-matched cases, whilst the small amount of material required is advantageous in paediatric patients.

Bone Marrow Transplantation↗
PubMed1992

Accessory cell damage and loss of overall white cell viability inhibit lymphocyte responses after ultraviolet-B irradiation but without evidence of in vitro suppression.

The effect of different doses of ultraviolet B irradiation (UVR) on the proliferative responses of Balb/c spleen cells has been tested. In 72-hour cultures, there was dose-dependent suppression of proliferation in response to phytohemagglutinin (PHA). Cell viability after UVR was found to be reduced in a dose- and time-dependent manner. Proliferation increased by greater than 100 percent after low-dose (20 J/m2) UVR when either normal or gamma-irradiated peritoneal cells were added to the cultures, but not at higher doses. Delaying UVR until 24 hours after stimulation of cultures with PHA did not substantially increase [3H]-thymidine uptake. Stimulation of mixtures of UV-irradiated and control cells or incorporation of medium conditioned with UV-irradiated cells provided no evidence of suppression of proliferation. The accessory cell population is an important target for UVR, but cells are physically damaged to the extent that, at higher doses, the response to PHA stimulation cannot be restored.

Animals↗
PubMed1992

Acquired factor XI inhibitor in chronic lymphocytic leukaemia.

A 71 year old man with chronic lymphocytic leukaemia (CLL) experienced excessive bleeding following transurethral resection of the prostate. Investigations showed a prolonged kaolin cephalin clotting time (KCCT) with low concentrations of factor XI. The prolonged KCCT was largely corrected by mixing with normal plasma but this correction was lost on incubation, confirming the presence of an inhibitor. He was treated with pulsed methylprednisolone and chlorambucil which resulted in the resolution of the bleeding problem and the loss of detectable circulating inhibitor.

Aged↗
PubMed1992

The alloimmunized patient: effective transfusion support and newer experimental approaches.

Refractoriness occurs in a proportion of patients who receive multiple platelet transfusions. Alloantibodies, in particular those directed against the class I human leucocyte antigens (HLA) present on the platelet surface, are frequently associated with accelerated platelet destruction and transfusion failure. Compatible platelets for transfusion may be found by selecting donations from HLA-typed individuals, crossmatching patients' sera against donor lymphocytes and platelets or both. Maintaining a large panel of HLA-typed apheresis donors is expensive and some mismatching is inevitable due to the polymorphic nature of the HLA system. Cross-matching may improve the outcome when HLA-matched donations are transfused and may also be a cost-effective strategy for the selection of compatible untyped platelets. Administration of intravenous immunoglobulin, plasma exchange and ex vivo removal of platelet HLA have been employed successfully in a few refractory alloimmunized patients but do not yet have an established role. Experimental studies in animal models suggest that it may be possible to induce tolerance to HLA and prevent alloimmunization.

Animals↗
PubMed1991

Studies of allogeneic bone marrow and spleen cell transplantation in a murine model using ultraviolet-B light.

Ultraviolet irradiation inhibits alloreactive and mitogen-induced responses and might reduce both graft-versus-host and host-versus-graft reactions after bone marrow transplantation (BMT). We have studied proliferative responses to mitogens and reactivity in mixed lymphocyte culture after irradiation with ultraviolet (UV)-B light using splenocytes from Balb/c (H-2d) and CBA (H-2k) mice. Response to mitogens and in MLC was strongly inhibited by 20 J/m2 and abolished at 50 J/m2. Clonogenic cell recovery (CFU-GM; CFU-S) after UV-B irradiation was also reduced. When bone marrow and spleen cells were transplanted from parent (Balb/c) animals into F1 hybrid (Balb/c X CBA) recipients, all animals died with features indicative of graft-versus-host disease (GVHD) in 34 days. If the grafts were first irradiated with 100 J/m2 of UV-B at a mean wavelength of 310 nm, then 76% survived to day 80 when they were killed and shown to have normal marrow cellularity. The remainder died in marrow aplasia or of GVHD. H-2 typing in a group of surviving recipients showed either donor hematopoiesis only (8 of 15), mixed allogeneic chimerism (5 of 15), or recipient type hematopoiesis (2 of 15). Higher doses (200 to 300 J/m2) were detrimental to survival with 88% of recipients dying in marrow aplasia. Syngeneic BMT in Balb/c mice showed slower hematopoietic reconstitution when the grafts were first irradiated with 100 J/m2. After BMT from Balb/c to CBA mice all recipients of unirradiated grafts died within 54 days. By contrast, after graft irradiation with 100 J/m2 survival of recipient animals to day 80 was 59%. If these grafts were treated with 50 J/m2 survival was only 26% with an increase in deaths due to GVHD. Hematopoiesis at day 80 in a group of survivors studied by Ig heavy chain allotyping indicated donor type hematopoiesis in 6 of 10 (50 J/m2) and 2 of 9 (100 J/m2). These data indicate that UV-B irradiation inhibits lymphocyte reactivity and can prevent GVHD. However, there is clear in vitro and in vivo evidence of stem cell damage, such that autologous marrow recovery was demonstrated in a proportion of recipients. In parent----F1 UV-irradiated transplants, sustained hematopoietic recovery was effected in the majority by donor stem cells.

Animals↗
PubMed1991

Immunomodulation by ultraviolet light: clinical studies and biological effects.

The interest of immunologists in ultraviolet (UV) irradiation stems from observations made in vitro and in vivo. In vitro, UV irradiation inhibits mitogen and mixed lymphocyte culture (MLC) responses and in vivo, it can induce cutaneous anergy, apparently via suppressor cells and serum factors. At present much interest is focused on the possible use of UV irradiation to permit transfusion without allosensitization and transplantation without either rejection or graft-versus-host disease (GVHD). Here, Derwood Pamphilon and colleagues discuss the current uses and potential of UV irradiation in transfusion and transplantation and relate these to experimental evidence on its effects at the cellular level.

Animals↗