Biomedical subjects
Publications and source records attributed to D C Linch.
Explore the source record for details and available documents.
Our previous work on the in vitro generation of cytotoxic T lymphocytes from the blood of 15-22-week-old fetuses, and on the induction of immunological tolerane in both radiation chimeras and neonatal mice, using T lymphocyte-depleted allogeneic bone marrow cells, has led us to believe that it should be possible to establish red cell chimerism in human fetuses by the infusion of allogeneic adult bone marrow cells. The essential prerequisite appears to be the removal of immunocompetent T lymphocytes from the bone marrow transplant, for new T cells generated from donor stem cells become tolerant to the histocompatibility antigens of the host's thymus and cannot, therefore, cause graft-versus-host disease (GVHD). Such an approach could be used in the treatment of fetuses diagnosed at an early stage as suffering from life-threatening inherited blood disorders. The experiments described here were designed to test this hypothesis in a sub-human primate species, Macaca fascicularis. Twenty-two cynomolgus monkeys received infusions of haploidentical (paternal) bone marrow between days 51 and 95 of gestation. There was no evidence of chimerism in animals inoculated after day 75 from mating. Eight out of 14 fetuses inoculated before day 70 were late intra-uterine deaths, four were hydropic and in one, histological confirmation of GVHD was obtained, indicating that tolerance can be induced at this time, as GVHD can occur only if donor cells survive. The T cell-depletion technique used here did not appear to prevent GVHD.
The response to treatment and survival has been assessed in 61 patients with pathological Stage IIA Hodgkin's disease with mediastinal involvement who were treated initially by supradiaphragmatic radiotherapy alone. Although 57 (93%) obtained complete remission, 29 have relapsed giving a total of 33 (54%) treatment failures. The percentage of patients actuarially disease free at 5 years is 44% although overall survival is 90%. The "bulk" of the mediastinal disease was assessed on a plain chest X-ray by measurement of the widest diameter of the mass compared to thoracic diameters at various levels as well as by determination of the area of the mass. The ratio of the widest diameter of the mass to the widest internal thoracic diameter provided the greatest prognostic information. Patients with a ratio greater than 0.33 (30% of total) had an actuarial disease-free survival of 24% at 5 years compared to 54% in patients with smaller mediastinal masses (P less than 0.05). Mediastinal bulk was not correlated with histological grade. Patients with the largest mediastinal masses (ratio greater than 0.37) (10% of total) have a lesser survival, but in the remainder, measurement of the mediastinal mass did not predict survival, indicative of the excellent salvage rate with subsequent chemotherapy. The implication of these findings for the treatment of stage IIA Hodgkin's disease with mediastinal involvement is discussed.
Explore the source record for details and available documents.
A recurrent theme in studies of the pathology of fatal Lassa fever in man is the lack of histological lesions to explain disordered cell function and death. Recently, we demonstrated the existence of a factor in the plasma of patients with Lassa fever which markedly inhibits the aggregation responses of normal platelets in vitro. To assess whether this factor could mediate more global cellular dysfunction, we studied the effects of Lassa plasma on the respiratory burst of neutrophils. Thirteen of 15 samples from patients in the acute phase of Lassa fever profoundly inhibited the amount of superoxide generated by normal neutrophils in response to the chemotactic peptide, f-met-leu-phe (FMLP) (mean superoxide generated = 54.7 +/- 6.1% of control). In contrast, eight of nine samples from patients who had infections other than Lassa fever enhanced the neutrophil response to the peptide. All Lassa samples which inhibited the ADP-induced aggregation responses of normal platelets inhibited the neutrophil response to FMLP. Unlike the effect on platelets, however, the inhibition of neutrophils was only apparent when the cells were stimulated within 5 min of exposure to the plasma. The inhibition of neutrophils is not due to either interference with FMLP-neutrophil binding or an effect on the NADPH-oxidase, suggesting a suppression of signal transduction. Our data suggest the inhibitory factor in Lassa plasma has global effects on cellular function, and may play a central role in the pathogenesis of this often fatal illness.
The administration of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) causes a transient leucopenia. Radionuclide labelling studies showed this to be due to margination of neutrophils and monocytes predominantly in the pulmonary vasculature. No evidence of complement activation was found. A rapid in-vivo rise in neutrophil cellular adhesion molecule (CAM) expression was observed paralleling the development of the neutropenia. Neutrophils exposed to rhGM-CSF in-vitro showed similar rapid increases in CAM expression. The adherence of chromium-labelled neutrophils to endothelial cell cultures was modestly but highly significantly increased by rhGM-CSF, an effect that was reduced by the binding of a monoclonal antibody to the beta chain of neutrophil CAM. The margination of phagocytic cells induced by rhGM-CSF administration is therefore likely to be due at least in part to increased expression of adhesion promoting glycoproteins. The demargination, however, occurred at a time when neutrophil CAM expression was still high, suggesting that dissociation of the neutrophil-endothelial cell interaction depends on factors other than downregulation of CAM expression. In-vivo modulation of phagocyte CAMS and adhesive properties by GM-CSF may be of importance in the normal inflammatory response.
We commenced a study in September 1981 to investigate the role of high-dose combination chemotherapy in the management of patients with non-Hodgkin's lymphomas who had failed conventional therapy. Fifty patients with diffuse intermediate- and high-grade non-Hodgkin's lymphomas were treated with high-dose combination chemotherapy with autologous bone marrow rescue (ABMT) and have a minimum follow-up of 1 year. Twenty patients had disease that was still responsive to conventional-dose chemotherapy, 15 had achieved a partial response (PR) to first-line therapy, and five were showing PR to salvage therapy after relapse. Twelve of these patients (60%) achieved complete remission (CR) (two following boost radiotherapy) and three patients have nonprogressive masses on computed tomographic (CT) scan as the only abnormality. None of these patients died during the procedure. Twenty-nine patients had disease not responsive to chemotherapy at conventional dosages: 19 had no response to first-line therapy and 10 showed no response to salvage therapy given after relapse. Only three of these patients achieved CR, all of short duration only. Only two patients in this group remain alive more than 2 years after the procedure and both have nonprogressive abnormalities on CT scan. Nine patients (31%) died of sepsis during the procedure. In those patients with disease not responsive to conventional-dose therapy, dose escalation is associated with a high procedure-related mortality and a low response rate. In those patients who still have chemotherapy-responsive disease the response rate is high and mortality is low.(ABSTRACT TRUNCATED AT 250 WORDS)
Explore the source record for details and available documents.
A monoclonal antibody (mAb), CLB/FcR gran I, reactive with the CD16 Fc receptor (FcRlo/FcRIII) of human cells, leads to calcium mobilization in large granular lymphocytes (LGL) but not in granulocytes. Identical responses are obtained with F(ab')2 fragments of this antibody, indicating that the response is independent of Fc-FcR binding, and that bivalent cross-linking of this receptor is adequate for optimal calcium mobilization. The calcium response was greater in CD3- LGL compared to CD3+ LGL, although the response was augmented in the latter cells by prior rosetting with sheep red blood cells (SRBC). Calcium mobilization in CD3- LGL induced by CLB/FcR gran I is associated with inhibition of natural killer cell (NK) killing, and inhibition of the enhanced NK killing induced by the anti-CD2 low-density monoclonal antibody, 9.1. This supports the view that the NK-enhancing activity of 9.1 is due to simultaneous binding to CD2 and CD16, and may in fact be transduced through the CD16 molecule. The variable reported effects of anti-CD16 antibodies on NK killing are likely to reflect the epitope bound rather than the isotype of antibody used, since F(ab')2 fragments of CLB/FcR gran I also inhibit NK killing.
Forty-four patients with refractory Hodgkin's disease were treated with high-dose combination chemotherapy followed by autologous bone marrow rescue. Twenty-two patients (50%) entered complete remission within 6 months of the procedure and four other patients are free of disease progression. Only two patients have subsequently relapsed from complete remission (CR). Bone marrow suppression was the predictable major toxicity of this procedure, and two patients (4.5%) died of sepsis during the aplastic phase. High-dose therapy with autologous bone marrow transplantation (ABMT) appears to be an effective salvage regimen for patients with refractory Hodgkin's disease.
Thirty-one patients with resistant Hodgkin's disease were treated by an identical high dose chemotherapy regimen and autologous bone marrow transplantation. Twelve of these patients received recombinant human granulocyte/macrophage colony stimulating factor (rh GM-CSF) in a phase I/II study. rh GM-CSF was administered by continuous infusion into an indwelling central venous catheter for 3-21 days at doses of 100-400 micrograms/m2/day. The patients receiving rh GM-CSF did not differ significantly from those who did not receive growth factor with regard to age, previous therapy or number of bone marrow cells infused. rh GM-CSF resulted in more rapid neutrophil regeneration, the average time to achieve a neutrophil count of greater than or equal to 0.5 x 10(9)/l being 17.5 days compared to 24.9 days in the control group (p less than 0.01). Platelet recovery was very varied and not accelerated by rh GM-CSF. Patients receiving rh GM-CSF had a similar infection rate (58% vs 68% in the control group), similar number of febrile days (5.0 vs 4.7 days) and similar period of hospitalization to the control group (30.1 vs 30.2 days). Randomized controlled trials are now required to define the clinical value of rh GM-CSF in the setting of autologous bone marrow transplantation.
Explore the source record for details and available documents.
Recombinant human granulocyte-macrophage colony-stimulating factor (rh GM-CSF) was administered by constant intravenous infusion to eight patients with malignant disease prior to chemotherapy. rh GM-CSF was given at a dose of 15 to 25 micrograms m-2 h-1 for 1 or 2 h. Neutrophil migration into an inflammatory zone was monitored throughout this period using a micropore skin window technique. Neutrophil migration into the micropore membrane prior to the commencement of the rh GM-CSF infusion was almost identical to that in eight normal control individuals (leading front distance of migrating neutrophils in 20-min period 81.3 +/- 7 microns in the patients compared to 79.4 +/- 4 microns in the control individuals). During the rh GM-CSF infusions there was a significant fall compared to controls in the number of neutrophils entering the membrane and the leading front distance (P less than 0.05). In four out of nine patient studies (eight patients) there was a greater than 30% fall from the pre-infusion level. In the control individuals the largest fall recorded was less than 10% and overall there was a progressive rise in the number of neutrophils entering the membrane throughout the period of study. This study suggests that intravenous infusion of rh GM-CSF may impair the ability of neutrophils to infiltrate an inflammatory focus.
It is shown that a mAb specific for the human 40-kDa FcR (FcRII) leads to activation of human monocytic cells but that extensive cross-linking of the receptor is required. Calcium mobilization can be induced in immature monocytic cells (undifferentiated U937 cells) and peripheral blood monocytes with an intact IgG1 anti-FcRII antibody (CIKM5) but not by F(ab')2 fragments of this antibody. The intact antibody can bind in a tripartite manner by its two F(ab') sites and its Fc-binding site whereas the F(ab')2 fragments of this antibody can only bind in a divalent fashion. A rise in intracellular free calcium ion concentration occurs when F(ab')2 fragments are cross-linked with F(ab')2 anti-mouse Ig indicating that more extensive cross-linking of FcRII is required rather than an obligatory requirement for an Fc-FcRII interaction. Calcium mobilization in response to intact or cross-linked F(ab')2 fragments of CIKM5 is associated with superoxide production only in IFN-gamma-primed peripheral blood monocytes and IFN-gamma differentiated U937 cells indicating that the activation signal produced via FcRII is inadequate to fully stimulate non-"primed" cells. A second mAb reactive with FcRII (2E1) does not cause calcium mobilization in monocytes or U937 cells, and partially blocks the effects of CIKM5. 2E1 also blocks CIKM5 superoxide production in IFN-gamma-primed monocytes and differentiated U937 cells. This may be explained in part by the fact that 2E1 is an IgG2a antibody and can only participate in bipartite binding with FcRII. When 2E1 is cross-linked with F(ab')2 anti-mouse Ig there is a small calcium response. This does not cause superoxide generation in IFN-primed monocytes but does do so in IFN-gamma differentiated U937 cells. FcRII is also expressed on granulocytes and some B cells but the effects of cross-linking the receptor on these cells differ from those seen in monocytes.
The potential value of sulphonated aluminium phthalocyanine (AISPc) as a purging agent for bone marrow autografts in acute myeloblastic leukaemia (AML) has been studied using in vitro clonogenic assays for normal (GM-CFC) and leukaemic (AML-CFC) progenitor cells. In nine out of 13 cases, the leukaemic blasts were found to be highly sensitive to AISPc. In six of the sensitive cases clonogenic assays revealed that only 2 +/- 1% of AML progenitor cells survived AISPc treatment under conditions which permitted a GM-CFC recovery of 60 +/- 11%. AISPc photosensitization was also shown to selectively eliminate the leukaemic cell line K562 from an in vitro model of minimal residual disease. Thus photosensitization using AISPc may be an effective method of purging marrow autografts in some cases of AML. Evaluation of the sensitivity of AML clonogenic cells at diagnosis may identify those patients in whom AISPc photo-purging may be of benefit at the time of an autologous bone marrow transplant.
Explore the source record for details and available documents.
Purified pertussis toxin (PPT) is a potent mitogen for human T lymphocytes and is shown to cause rapid calcium mobilization in resting T cells, a T-cell line and CD3- lymphocytes with natural killer (NK) activity. In resting T cells the PPT activation is associated with cytoplasmic alkalinization. A similar rise in intracellular free calcium ([Ca2+]i) and cytoplasmic alkalinization is observed with activation through the antigen receptor complex. The effect of PPT is unlikely to be mediated through this pathway, however, as it can mobilize calcium in lymphocytes that do not express the CD3-Ti complex. In contrast to several other cell types, re-incubation of resting human T cells with PPT, up to a dose of 100 ng/ml for 2 hr does not block subsequent agonist-induced calcium mobilization dependent on G protein-mediated phospholipase C activation. Mitogenic doses of PPT cause a modest reduction in subsequent agonist responses, but this is likely to be due to a post-activation refractory state rather than G protein inactivation.
Four patients with advanced resistant malignant disease received recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) for 10 days. All developed a moderate neutrophilia and monocytosis over this period. A transient phagocytopenia was observed during the first hour of administration. Radionuclide labelling studies showed that this cytopenia was due to sequestration predominantly within the lungs and that the recovery was due to re-entry of the same cells into the circulation. Studies of neutrophil lobularity during this time showed no reduction in lobe count suggesting that there had been little if any release of immature cells from bone marrow reserves. Skin window responses were present in 2 out of 3 patients during the period of neutropenia showing that cells were also present in the marginated pool of the skin at this time.