The impact of antithymocyte globulin on short-term toxicity after allogeneic stem cell transplantation.

Antithymocyte globulin (ATG) is commonly used in allogeneic haematopoietic stem cell transplantation (HSCT). Little information is available, however, as to the optimal protocol for use and the side-effects occurring if ATG is administered in high daily doses (10-30 mg/kg). We report our experience with ATG Fresenius (ATG-F) in conditioning for allogeneic HSCT. During a period of 3 days, 47 patients received doses between 10 and 30 mg/kg either over 4 h preceded by 1-1.5 mg/kg prednisolone 30 min before the start of ATG-F (protocol A) or alternatively, over 12 h with 3-4 mg/kg prednisolone being administered before and 6 h after start of ATG (protocol B). During treatment with ATG-F, the side-effects observed included inflammation, disseminated intravascular coagulation, hyperdynamic circulation and renal dysfunction. Although these complications caused substantial morbidity, they were reversible within a few days. Side-effects were significantly more severe in patients treated according to protocol A than in those treated according to protocol B. As prolonged infusion of ATG-F does not reduce T cell clearance due to the long half-life of ATG-F, and since less cytokine release during conditioning might have beneficial long-term effects, we recommend administering ATG-F over 12 h preceded by high-dose steroid treatment.

Early loss of renal transplants in patients with thrombophilia.

BACKGROUND: We considered the possibility that thrombophilia may propagate graft thrombosis and therefore we evaluated the protein C system, which is a natural anticoagulant. Potential alterations in this system include protein C or protein S deficiency, inhibition through a lupus anticoagulant (LA), or a resistance to activated protein C due to the factor V Leiden (FVL) mutation. METHODS: One hundred thirty-two consecutive renal transplant patients, not known to have abnormal thrombostasis, in whom 1-year graft survival could be assessed, underwent laboratory testing for protein C or S activity, LA, and FVL. Transplant survival and demographic data were extracted from the hospital record. RESULTS: We identified 18 patients with thrombophilia (FVL, 10; LA, 6; protein S, 2) who had received a total of 28 renal transplants. Of these 28 transplant recipients, 11 transplants were lost within the first year, compared with 21 of 155 transplants to 114 patients without thrombophilia (P=0.0003). Median graft survival for patients with thrombophilia was 30 months (range: 0 to 166), compared with 86 months (range: 0 to 212) for patients without thrombophilia (P<0.01). The presence of thrombophilia represented a 3.5-fold (95% confidence interval, 2.3-5.3-fold) risk for 1-year graft loss. CONCLUSION: In this retrospective study, patients with thrombophilia had a significantly higher risk of early transplant failure. These data point toward a potential contribution of thrombophilia to transplant loss, a hypothesis that needs further study.

Platelet morphology in patients with mechanical circulatory support.

OBJECTIVE: Mechanical circulatory support is a therapy for patients with end stage cardiac insufficiency. The thromboembolic events are feared complications during support, due to the surface thrombogenicity of the implanted device. Activated blood platelets play a major role in this context. Consequently the platelet morphology of patients was investigated. METHODS: Platelets of eight patients were observed by means of scanning electron microscopy during the period of support with the Novacor left ventricular assist system N100. Blood was collected preoperatively and daily during the first week as well as weekly during the first 3 months. Samples were fixed with cacodylic-acid buffered glutaraldehyde. Platelet alterations were classified as non-activated, activated and aggregated, based on the so-called 'shape change' morphology. In addition, blood coagulation parameters were evaluated (e.g. activated partial thromboplastin time, prothrombin time, antithrombin III). RESULTS: Preoperatively, 15.0 +/- 4.6% (overall mean values) of activated platelets were found. Within the first postoperative week, the mean level of activated platelets increased to 32.8 +/- 8.0% (P < 0.05). Comparing short- (< 30 days; n = 4) vs. long-period (> 30 days; n = 4) support, a significant difference of activated platelets was evaluated (24.3 +/- 3.3% vs. 34.8 +/- 3.4%, P = 0.004). A correlation was found between the values of activated clotting time and activated platelets. Specific platelet deformations and damages appeared during support, which could not be found preoperatively. CONCLUSIONS: The platelet morphology showed alterations in all patients probably most strongly induced by the surface activation of the implanted device. These observations should be taken into consideration in management of postoperative anticoagulation therapy.

Protein C, protein S and antithrombin III levels in the course of bone marrow and subsequent liver transplantation due to veno-occlusive disease.

Veno-occlusive disease (VOD) of the liver is one of the most frequent fatal complications after bone marrow transplantation (BMT). A decrease of natural anticoagulants, in particular protein C (PC), has been assumed to be involved in the pathogenesis of the disease. We determined PC and antithrombin III (AT III) levels in two patients undergoing BMT and subsequent liver transplantation due to VOD. Additionally, in one of the patients protein S (PS) levels were also measured. Normal baseline (day-8) PC levels (86 and 89%) were markedly reduced in both patients at the time of VOD manifestation on day 20 and 40, respectively (26 and 31%). PS levels lay within the normal range from day-8 (before myeloablative chemotherapy) until one week after clinical onset of VOD when substitution therapy with fresh frozen plasma (FFP) was initiated. AT III levels decreased moderately during the second and third posttransplant week, but were normal in the patient with a late clinical manifestation of VOD. In both patients PC and PS levels lay within the normal range after liver transplantation which was performed on day 41 and 79, respectively. AT III was substituted several times. Both patients died due to infectious complications on day 141 and 101, respectively. The data confirm previous reports that a decrease of PC is observed in BMT recipients and can be associated with hepatic vein occlusion. Whereas the relevance of AT III is uncertain, PS does not seem to be involved in the pathogenesis of VOD. Liver transplantation lead to normalization of PC levels, but its significance remains to be discussed in terms of ethical justifiability, medical feasibility and costs.

Adhesion of human T lymphocytes to endothelial cells isolated from the umbilical vein: I. Similar binding patterns of normal and rheumatoid T cells.

Interactions between endothelial cells (EC) and cells of the immune system play a major role in the initiation of inflammatory processes. To study these events in vitro, an assay system was developed whereby the adhesion of radioactively labelled T cells to EC was measured in normal donors and patients with inflammatory rheumatic diseases including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Human EC were isolated from umbilical cord veins, and peripheral blood T cells labeled with 51Cr were added to these EC cultures and to human foreskin fibroblasts as controls. Specific binding was calculated by subtraction of the radioactivity contained within the fibroblast controls from the total values obtained with EC. Kinetic experiments demonstrated a mean specific EC binding of 18% of total T cells after 2 h of incubation, increasing steadily to a maximum of 47% after 8 h. These results were highly reproducible using the same donors in separate experiments. Comparing normal individuals to patients with RA and SLE, no significant differences were found in adhesion patterns of peripheral blood T cells.

Adhesion of human T lymphocytes to endothelial cells isolated from the umbilical vein: II. Enhanced binding of in vitro activated T lymphocytes.

Interactions of the vascular endothelium and cells of the immune system play a major role in the initiation and sustaining of cell mediated immune response in autoimmune diseases, chronic inflammatory processes and graft rejection. In the present investigation, the initial step of T cell-endothelial cell interactions, namely the adhesion of T cells to endothelial cells, was studied with special emphasis on the binding of T cells activated in vitro with lectins and by allogeneic cells as well as on the effect of pretreating endothelial cells with IFN-gamma. Human endothelial cells (EC) were isolated from the umbilical cord vein; human foreskin fibroblasts (HFF) served as control cells. While resting T cells demonstrated an adherence of 53% to EC and 20% to HFF, PHA blasts showed a binding of 90% to EC and 59% to HFF. Similar results were obtained using MLC blasts from mixed leukocyte cultures. Thus, the activation process triggered a striking enhancement of T cell binding not only to EC, but also to HFF that were taken as mesenchymal control cells. Pretreatment of EC and HFF with IFN-gamma, inducing Ia antigens on both cell populations, led to a significant increase of binding of resting T cells to EC. Of special interest, T lymphocytes also exhibited a considerably increased adherence to Ia-positive rheumatoid synovial fibroblasts. Taken together, these findings indicate that both the activation of T cells as well as endothelial cells results in a greatly enhanced binding.