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Biomedical subjects

V Lenhard

Publications and source records attributed to V Lenhard.

At least 19 recordsLinked to original sources
PubMed1994

[Solidscreen II Enzyme: a complete test method using Solidscreen II].

An extended application of the solid-phase antiglobulin test Solidscreen II consists in the use of enzyme-treated test cells. Beside the increased sensitivity in the detection of weak Rh antibodies, 'real enzyme-reactive antibodies' can be detected. A total of 818 serum samples and 404 EDTA plasma samples were tested for red cell antibodies. In addition to Solidscreen II, 12 antibodies (0.98%) were detected and identified.

Autoantibodies↗
PubMed1993

[Solid phase techniques in blood group serology].

As alternatives to hemagglutination, solid-phase red blood cell adherence assays are of increasing importance. The adaptation of the new techniques to microplates offers several advantages over hemagglutination. Using microplates the assays may be processed semiautomatically, and the results can be read spectrophotometrically and interpreted by a personal computer. In this paper, different red blood cell adherence assays for AB0 grouping, Rh typing, Rh phenotyping, antibody screening and identification, as well as crossmatching will be described.

ABO Blood-Group System↗
PubMed1992

Human monoclonal antibodies for the differentiation of Rh-D categories.

With the introduction of human monoclonal antibodies against antigens of the Rh-system it was possible to solve a series of problems, as, for instance, the permanent availability of reagents. Another problem, the classification of D-categories with a panel of specific monoclonal antibodies, also might be solved by the production of such antibodies. Especially the classification of Cat. VI-cells is of great importance. We present a panel of five human monoclonal antibodies useful for the definition of Rh-D categories. The antibodies are designated as BS221, BS227, BS228, BS230 and BS231. By positive or negative reactions with expected category cells it is possible to determine the corresponding category. All Cat. VI-cells of a defined panel could be identified. Of particular interest is the antibody BS221 due to its reactivity with Cat. VI-cells. The fact, however, that BS221 is missing the detection of some Cat. VI-cells indicates a further subdivision of Cat. VI.

Antibodies, Monoclonal↗
PubMed1992

Human monoclonal antibodies for the differentiation of RhD categories.

With the introduction of human monoclonal antibodies against antigens of the Rh system it was possible to solve a series of problems as, for instance, the permanent availability of reagents. Another problem, the classification of D categories with a panel of specific monoclonal antibodies, also might be solved by the production of such antibodies. Especially the classification of cat. VI cells is of great importance. Here we are presenting a panel of 5 human monoclonal antibodies useful for the definition of Rh-D categories. The antibodies are designated as BS221, BS227, BS228, BS230 and BS231. By positive or negative reactions with expected category cells it is possible to determine the corresponding category. All cat. VI cells of a defined panel could be identified. Of particular interest is the antibody BS221 due to its reactivity with cat. VI cells. The fact, however, that BS221 misses the detection of some cat. VI cells indicates a further subdivision of cat. VI.

Antibodies, Monoclonal↗
PubMed1990

Human leucocyte antigens in idiopathic nephrotic syndrome in children.

An association of the idiopathic nephrotic syndrome (NS) with certain human leucocyte antigens (HLA) has been reported repeatedly. The aim of this study is to characterize further the clinical and histological features of patients with NS in relation to their HLA phenotypes. HLA antigens were determined in 132 paediatric patients with NS. In 91 steroid-sensitive patients (usually associated with minimal glomerular changes), the antigen frequencies of HLA-DR3, HLA-DR7, and HLA-B8, -DR3 combined were significantly increased compared with controls. The strongest association was observed with the combined occurrence of HLA-B8, -DR3, -DR7 (relative risk 21.5). This association and that with HLA-DR3 alone were strongest in the presence of frequent relapses and steroid dependence compared with children without or with infrequent relapses. The pattern of HLA antigens was similar in the 57 steroid-sensitive patients with biopsy-proven minimal glomerular changes. In 41 children with steroid-resistant NS (usually associated with focal segmental glomerulosclerosis) a similar trend for increased antigen frequencies was found but the data were significant only for the combined occurrence of HLA-B8, -DR3 and -DR7. In all patients combined the frequency of the HLA associations was significantly lower when the age of onset was greater than 8 years compared with that of younger patients. It is concluded that the immunogenetic background of the steroid-sensitive and steroid-resistant NS is different and age-dependent.

Adolescent↗
PubMed1987

[Effect of immunomodulation following allogeneic blood transfusion on tumor neogenesis and growth--experimental studies in rats].

The influence of allogeneic blood transfusions (BT) on experimental tumor growth was investigated in three syngeneic, one allogeneic and one autochthonous tumor model in the rat. Con A induced T-cell response, relative distribution of lymphocyte subsets using flow cytometry and cytotoxic antibodies were determined. No differences in take rate, induction time, incidence and growth rate of tumors were observed in the different models. A significant decrease of cell-mediated immunity and a significant increase of peripheral Ia-positive cells could be observed. The relative distribution of T-cell subsets showed no differences between BT-groups and controls.

Adenocarcinoma↗
PubMed1985

Suppression of antibody response and prolongation of skin graft survival by multiple blood transfusions in the rat.

The effect of blood transfusions (BT) on antibody response and skin graft survival was studied in the strongly MHC-incompatible BN and LEW combination. One-to-three BT induced high titer antibodies. Additional BT, however, led to a decrease of antibody titers. After 15 BT the recipients either had no detectable antibodies, or they had very low antibody titers. This suppression of response was shown to be distinct from a simple loss of antibody activity caused by lack of further antigenic challenge. In multiple transfused rats, humoral nonreactivity persisted in spite of rechallenge with antigen; in animals that lost their antibodies as a result of lack of further stimulation, an additional BT boosted strong antibody production. In LEW recipients of multiple BN transfusions, not only the specific anti-BN response but also reactivity to third-party BUF blood was suppressed. However, whereas the donor-specific response (anti-BN) was largely inhibited after a ten-week interval, the response to third-party BUF blood recovered. The state of humoral nonreactivity could be transferred by spleen cells to nontransfused syngeneic animals. In LEW rats that received three injections of 5 X 10(7) "suppressor" spleen cells, the antibody response to BN blood was strongly impaired as compared with animals that received normal spleen cells. BN or (BN X LEW)F1 skin grafts survived significantly better in multiple transfused LEW rats than in nontransfused controls. This was even more pronounced when ALS was given additionally. Third-party grafts (BUF) survived only slightly better than controls. It is concluded that multiple BT (1) result in humoral anti-donor nonreactivity secondary to an initial antibody response, (2) induce strong specific and weak nonspecific suppressor cell activity, and (3) increase skin graft survival.

Animals↗
PubMed1985

Effect of allogeneic blood transfusions on the growth of two different tumours in the rat.

The effect of allogeneic blood transfusions on tumour growth was studied in the rat. BD IX animals pretreated by five blood transfusions from SD rats were transplanted with two different syngeneic malignant neurogenic tumours (neurinoma, ependymoma). The tumour growth rates in the transfused animals were compared to those of non-transfused controls. No accelerated growth rates of both types of tumours were observed in transfused animals. As these data are in contrast to the findings of other authors, further studies are needed to evaluate the effect of blood transfusions on tumour growth.

Animals↗
PubMed1985

Transfusion-induced enhancement of prostaglandin and thromboxane release in prospective kidney graft recipients.

Pre-transplant blood transfusions (BT) improve the survival of kidney grafts. Apart from specific immunoregulation by T suppressor cells or anti-idiotypic antibodies, the role of non-specific immunoregulatory factors, such as prostaglandins is being discussed as a possible mechanism for this effect. We studied the in vitro prostanoid release from peripheral mononuclear cells following three deliberate blood transfusions. Twenty-five previously non-transfused dialysis patients were studied. Spontaneous and LPS-induced prostaglandin E (PGE) and thromboxane B2 (TXB2) were determined in cell-free culture supernatants by fluid phase RIA. Transfused patients exhibited a more rapid onset and steeper increase of prostanoid production. After 24 hours incubation, the spontaneous and LPS-induced PGE release of pre- and post-BT cells was significantly different (pre-BT: 2.1 and 5.1 ng/ml; post-3-BT: 5.0 and 7.9 ng/ml; p less than 0.01). Pre-BT cells released considerably lower amounts of TXB2 than post-BT cells (spontaneous release: 39 vs 88 ng/ml; LPS-induced release: 62 ng/ml vs 129 ng/ml; p less than 0.05). After correction for monocytes as defined by monoclonal antibodies, post-BT cells again showed increased prostanoid release as compared to pre-BT cells. Therefore, the enhanced PGE and TXB2 release of post-BT cells is not caused by an increase merely in the number of monocytes. Rather, BT appear to induce an enhanced release of prostanoids by activation of monocytes. We also found a correlation between the number of BT and the amount of prostanoid release.

Adolescent↗
PubMed1984

A rapid screening technique for lymphocytotoxic antibodies using tray-frozen lymphocytes.

A method whereby sera can be screened for the presence of lymphocytotoxic antibodies within 4 hr using lymphocytes frozen in microtest trays is described. The reactions of the sera of 48 hemodialysis patients against freshly prepared lymphocytes were compared with those against tube-frozen (384 reaction pairs) and tray-frozen (864 reaction pairs) cells. There was a better than 90% concordance, and only 3% of the reactions differed from negative to strongly positive or vice versa. Preliminary results indicate that the method is also suitable for B-cell (HLA-DR) antibody testing. Routine screening against 50- or 100-cell panels can be accomplished more rapidly and more efficiently using tray-frozen lymphocytes. The data matrix for analysis of a serum's HLA specificity is greatly reduced in comparison to the conventional screening technique, rendering the method particularly suitable for microcomputer processing.

Antilymphocyte Serum↗
PubMed1983

[Mesangial IgA-glomerulonephritis].

IgA-glomerulonephritis represents the most frequent glomerulonephritis (GN; 20%) among our patients. In contrast to data from the literature the prognosis is not benign. Renal insufficiency developed in 17 out of 50 investigated patients within 4 to 96 months, 3 of these patients had to undergo dialysis. Eleven of the 17 patients still had a normal renal function at the time of diagnosis. Malignant hypertension was present in 5 patients. An unfavourable course was predictable in cases of male gender, proteinuria, hypertension, age above 30 years, and histological changes indicating glomerulosclerosis, tubular atrophy, interstitial fibrosis and vascular lesions. Increased serum IgA levels, circulating IgA complexes, association with certain HLA-B or -Dr antigens as well as clinical symptoms and signs of haematuria, dysuria and kidney pains were not helpful either for diagnosis or for prognosis. The value of skin biopsy was comparatively small. Positive IgA demonstration was possible in 12 out of 41 cases with IgA-GN, however, also in 4 out of 21 patients with non-IgA-GN. None of 50 probands without renal disease showed IgA. Five out of 7 skin biopsies demonstrated IgA2, one IgA1 and one both IgA1 and IgA2. Increased serum IgA levels were found in a high percentage (21 out of 38 patients). The same applied to circulating IgA-complexes (8 out of 33 patients).

Adolescent↗
PubMed1983

HLA-DR-MT matching improves graft survival rate in cadaver kidney transplantation. A prospective multicenter analysis of the South German Cooperative Study Group for Kidney Transplantation.

The influence of prospective HLA-DR matching on the graft survival rate was investigated in a multicenter analysis of 85 transplants. Simultaneously in a retrospective analysis of graft outcome the importance of matching for MT-antigens MT1, MT2 and MT3 as a newly defined B-cell alloantigen system was evaluated. HLA-DR antigens and MT-specificities were determined on B-cells enriched by nylon-wool filtration using locally well characterised HLA-DR antisera and the antiserum set of the 8th International Histocompatibility Workshop ("disease set") which allowed the definition of the HLA-DR specificities HLA-DR 1-9 and of the MT-antigens MT1-3. HLA-DR matching showed a significantly improved graft outcome only in HLA-DR identical donor-recipient combinations. In 11 of 60 patients with one HLA-DR compatibility additional matching for two MT-antigens, however, improved the two year graft survival rate from 60% to 91%. Altogether 17 patients were matched for two MT-specificities with their kidney donor and showed a superior prognosis of 94% at two years compared to 53% or 17% of recipients with one or zero MT compatibility. Graft outcome in this patient group was also superior to that of HLA-DR identical or HLA-AB identical grafts. These data suggested that the MT-system rather than the HLA-DR antigens may be of critical importance in cadaver kidney transplantation. In addition a favorable influence of pretransplant blood transfusions on less HLA-DR matched grafts was confirmed.

B-Lymphocytes↗
PubMed1983

Immunological factors influencing renal graft survival.

The results of clinical renal transplantation are determined mainly by immunological factors, the most important of which are compatibility for the HLA chromosomes and pretransplant blood transfusions. Other factors include HLA matching in cadaver transplantation, compatibility for the Lewis blood group system, and sensitization to lymphocyte panels or to endothelial-monocyte antigens. Performance of the previous graft is the most reliable predictor of success in recipients of retransplants. Because several immunological factors may interact, multiple variables must be considered simultaneously.

Blood Transfusion↗
PubMed1983

Influence of Lewis and other blood group systems in kidney transplantation.

In 167 first cadaver kidney recipients and their donors the blood groups ABO, Rhesus, Lewis, MN, Ss, P, Kell and Duffy were determined. The influence of incompatibility in each system as well as of simultaneous presence of several mismatches was analysed. Whereas one-year graft survival of Lewis-compatible grafts was 67 per cent (p = 0.02). The other blood groups showed no significant effect on graft outcome. Cumulative red cell incompatibilities, however, led to decreased survival rates. One-year graft survival in the group with greater than or equal to 4 incompatibilities was only 51 per cent versus 69 per cent in transplants with less than 4 incompatibilities (18% difference, p less than 0.01). When the Lewis system was excluded from analysis, the difference in survival rates was reduced to only six per cent. These data indicate that cumulative incompatibilities of red cell antigens have an unfavourable effect on graft survival. Of the different blood groups, the Lewis system is of major importance.

Blood Group Antigens↗