Biomedical subjects
Publications and source records attributed to W Mempel.
Stimulation of lymphocytes with mitogens and antigens is an established model for in vitro testing of immunoreactivity. Due to the great variability of blastogenic response the interpretation of these results is difficult. Our results suggest that multivariate experiments and statistics improve the interpretation.
In blood samples of 88 healthy donors various red cell, HLA-A, -B, -Cw and -Dr antigens were determined by standard methods. Lymphocyte reactivity was measured by 3H-thymidine uptake into DNA of lymphoblastic cells stimulated by 14 different mitogens and antigens. Cluster analysis confirmed by t test and F test defined 3 distinct clusters of lymphocyte reactivity. Cluster 1 in 70% [relative risk (r.r.) 109, p < 0.001] and cluster 3 in 92% (r.r. 33, p < 0.01) showed significantly different cumulations of 3 or more increased characteristic red cell and HLA antigens. Our data suggest that the patterns of both red cell and HLA antigens play a major role in defining immunoreactivity.
A variety of antibody screening tests are available to detect immunization in patients' sera. However, antibodies can be observed only if corresponding antigens are present on test cells used by an antibody screen. By comparing available test cell kits of different manufacturers we revealed various specificities of antigens present or absent on these cells. Using by an antibody screen Wr(a+), Co(b+) and Kp(a+) test cells additionally to available test cells, we detected in 1000 sera of patients 13 anti-Wr(a) and 1 anti-Co(b) besides 17 antibodies with different specificities.
Functional characterization of subsets of T lymphocytes is essential for transplantation studies in dogs, as it is in other species. We studied the function of T cells separated by two mouse monoclonal antibodies recognizing complementary subsets--an antibody directed to canine T cells (MdT-P1) with an up-regulating function, and an antibody directed to human CD 8 (MT811) that cross-reacts with down-regulating canine T cells. Immunorosetting with sheep red blood cells and Percoll gradient allowed us to study depleted and enriched fractions. Their function was tested in mixed lymphocyte culture (MLC), cell-mediated cytotoxicity (CML), and coculture with B cells in a hemolytic plaque assay (PFC). In MLC, MdT-P1-positive cells showed a high proliferative response, and MT811-positive cells responded poorly to allogeneic cells. Vice versa, MT811- negative cells responded strongly, and MdT-P1-negative cells were poor responders but strong stimulators. Effector cells of CML were separated following 8 days of culture and prior to mixing with target cells. Enriched and depleted fractions with either antibody showed low cytotoxic activity as compared with unseparated cells. When added to unseparated effector cells MT 811-positive cells suppressed cytotoxicity. B cells were obtained by rosetting with staphylococcal protein A (SPA). Their immunoglobulin production was studied following 6 days of culture stimulated by pokeweed mitogen in a reverse hemolytic plaque assay. Again, MT 811-positive cells added to the culture suppressed, and MT 811-negative cells enhanced immunoglobulin production. In conclusion, immunorosetting with two monoclonal antibodies allowed us to distinguish subpopulations of canine T cells with up-regulating (helper/inducer) from those with down-regulating (suppressor) activity.
A possible connection between immunological alterations and schizophrenia has been discussed for many years. We studied 55 schizophrenic patients in an acute stage of illness before they began neuroleptic treatment. 35 patients who showed clinical improvement on neuroleptics, and 51 healthy controls. Our interest was focused on parameters of cellular immunity. We found an increased lymphocyte response to stimulation with pokeweed mitogen (PWM) and phytohemagglutinin (PHA) in patients before neuroleptic therapy and also an increased response to stimulation with PWM and PHA during treatment compared to controls. Stimulation with antigens generally showed a lower lymphocyte response in patients than in controls, but the difference was only significant after stimulation with tuberculin before neuroleptic treatment and after stimulation with varidase, diphteria-toxoid, tuberculin, vaccinia, and rubella during neuroleptic treatment. The number of CD3+ and CD4+ cells, but not the number of CD8+ cells, was increased before and during treatment in comparison to controls. Suppressor-cell activity was reduced in three different suppressor cell assays before and during neuroleptic medication compared to controls. We therefore conclude that alterations of the immunological system which are, as has been demonstrated, not due to treatment with neuroleptics might play a role in schizophrenia.
A newly developed adsorption filter has been evaluated for the removal of white cells (WBCs) from platelet concentrates. It consists of surface-modified polyester fibers and can be used at the patient's bedside. WBC mean removal rate was 98.8 +/- 0.9 percent, and platelet recovery was 99.0 +/- 0.7 percent. The aggregation curves (ADP, collagen) and hypotonic shock response of platelets were not influenced by the filtration, and the plasma electrolyte and lactate dehydrogenase concentrations were unaffected. Transmission and scanning electron micrographs showed no difference in platelet ultrastructure before and after filtration. Determination of posttransfusion platelet recovery did not reveal any significant difference from that of nonfiltered platelets. The tested filter seems to be a suitable device for WBC depletion of single-donor platelet concentrates at the bedside.
Bacterial neuraminidase plays an important role in the pathogenesis of some haemolytic anaemias. It divides neuraminic acid from the red cell surface to expose a hidden antigen (Thomsen-Friedenreich antigen, T). A physiologically circulating antibody can then react with the uncovered T and cause a rapid haemolysis. This study demonstrates the presence of T on human vascular endothelium. Similar to red cells it is exposed by the action of bacterial neuraminidase. The subsequent reaction with the physiological antibody could be involved in the pathogenesis of vascular damage observed in severe cases of bacterial septicaemia.
The long-term bone marrow culture system (LTBMC) consists of an inductive environment provided by a marrow-derived adherent layer which induces pluripotent stem cell replication. The activity of IL-6 was analyzed in micro LTBMC as a potential stem cell regulator. Immediately after initiation there was a tremendous increase in IL-6 activity. With each refeeding, IL-6 levels rose until confluency of the stromal layer was reached at week two to three post initiation. As a working hypothesis for further investigations, we suggest the immediate shift of stem cells after refeeding from a non-cycling into a cycling state might be mediated by the steep increase of IL-6 alone or in cooperation with other factors.
Explore the source record for details and available documents.
To avoid the risk of diseases transmitted by homologous blood, predeposited autologous blood is useful for elective surgical patients. World-wide, there is disagreement over whether complete donor testing should or should not be done on autologous collections. There are a variety of testing concerns which have evolved into reasons for testing all autologous units for the presence of infections disease markers. One of the reasons is the risk of giving the wrong (untested) blood to the wrong patient and transmitting HIV (and thus AIDS) or viral hepatitis. Another stated concern is the risk of creating additional problems in the laboratory by treating some units differently than other units. The argument continues that without this testing, blood bank and hospital personnel may be unnecessarily exposed to blood that has the potential to cause illness. Another justification for testing is given when the blood bank participates in crossover (transfusing blood to recipients other than the autologous donor/patient).
Optimal storage of platelet concentrates is still an unsolved problem. The present paper demonstrates changes in morphology and function of stored platelets. Transmission microscopy reveals a loss of organelles as well as a progredient destruction of cell membranes during storage. At the same time in vitro aggregability is clearly diminished. Therefore, further investigations seem to be necessary to improve storage conditions of platelets.
Explore the source record for details and available documents.
A newly developed filter-system (PL 100) for the removal of leukocytes from platelet concentrates was tested. It removes contaminating leukocytes by 99.7 +/- 0.6%. The platelet loss was calculated as 25.7 +/- 9.5%. The filtration process does not influence the filtered platelets; plasma-electrolytes, LDH-concentrations, platelet aggregation curves and serotonin-release remain constant. In addition, platelet ultrastructure is not influenced by the filtration. In spite of the high platelet loss, the tested filter-system seems to be a suitable alternative to the conventional methods for the removal of contaminating leukocytes from platelet concentrates.
Determinants for homologous blood transfusion and its influence on postoperative and long-term results were evaluated in 439 curatively resected colorectal cancer patients. The rate of transfusion was significantly higher in rectal cancer, large tumors, advanced pT stage and extended resection but not in tumor stenosis, lower graded tumors, advanced Dukes stage or less experienced surgeons. Transfused patients showed significantly more postoperative complications, higher recurrence rates as well as less favorable long-term survival. Homologous blood transfusions are negatively correlated to survival rates.
Numerous techniques have been established for preparing white cell-poor blood, such as centrifugation, sedimentation, freezing, and filtration. All of these methods have disadvantages that restrict their practical use: they are time-consuming, they require the facilities of a blood bank, and the white cell-poor units cannot be stored. Therefore tests have been performed on two filter systems that make possible the depletion of white cells directly at the bedside. Both filters have a high white cell-removal rate. The number of residual white cells in 1 unit of packed red cells was calculated as 1.08 +/- 0.53 x 10(7) in one system and 1.54 +/- 0.71 x 10(7) in the other. The filters do not affect the filtered red cells. Pressure filtration is performed without significant loss of efficiency. One of the systems can filter 2 units via one filter; however, handling the filters is tedious, and both filters are characterized by a low red cell recovery. Despite these disadvantages, the tested filter systems provide an effective device for preparing white cell-poor blood at the bedside. They are a suitable alternative to the conventional methods.
In order to evaluate the influence of leukocytes in whole blood on the standard blood bank conditions for storage, we compared several parameters of red cells, leukocytes and platelets in leukocyte-rich and leukocyte-poor whole blood over a storage period of 5 weeks. The leukocyte-depleted units were prepared by filtration with a leukocyte trapping filter (Sepacell R500A). Our data indicate improved storage conditions, made evident by significantly lower cell damage: smaller increases of elastase, beta-thromboglobulin and lactate dehydrogenase in leukocyte-depleted blood. This improvement was achieved in a simple two-bag system using only filtration, without addition of rejuvenating solutions. In addition, this procedure allows greater flexibility in the use of filtrated blood for transfusions.
A newly developed filter-system (Sepacell PL) for the removal of leukocytes from single donor platelet concentrates was tested. It removes contaminating leukocytes by 99.9%, the platelet loss was calculated as less than 1%. Platelet ultrastructure and function do not seem to be altered by the filtration. Therefore, the tested filter system seems to be a suitable device for leukocyte depletion of single donor platelet concentrates. Further clinical studies, however, are necessary to prove the efficiency of the filter system in preventing alloimmunization in vivo.
We tested in vitro lymphocyte reactivity using 5 mitogens and 9 antigens, measured lymphocyte and lymphocyte subpopulation counts, granulocyte chemotaxis and adherence in 10 patients with centroblastic-centrocytic lymphoma (CB-CC), 7 patients with centroblastoma (CB) and 88 healthy controls. The control group could be divided into 3 clusters with significantly different lymphocyte reactivity by means of cluster and discrimination analysis (BMDP2N): 21 high-, 18 medium- and 49 low responders. Comparing lymphocyte reactivity of CB-CC and CB patients to each of the 3 immunofunctional different control groups yielded the surprising result that both malignant lymphomas are equivalent to the low responding control group and show a low, but still normal in vitro immune function.