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G Dietrich

Publications and source records attributed to G Dietrich.

At least 19 recordsLinked to original sources
PubMed1995

Variable region-connected, dimeric fraction of intravenous immunoglobulin enriched in natural autoantibodies.

The beneficial effect of intravenous immunoglobulin (IVIg) therapy in patients with autoimmune diseases is at least partially dependent on the content in IVIg of antibodies capable of interacting with variable regions (idiotypes) of autoantibodies. In the present study, we have evaluated the antibody activity to a panel of self and environmental antigens of IVIg preparations and their dimer-enriched fractions. Dimers were either obtained by affinity chromatography of IVIg on Sepharose-bound F(ab')2 fragments of IVIg or by size exclusion gel filtration chromatography of IVIg. Enrichment of IVIg in dimers was found to be associated with an increase in the antibody activity against self-antigens as compared with unchromatographed IVIg. Our findings extend previous observations on enhanced autoantibody content of the affinity chromatography-separated 'connected' fraction of IVIg and suggest that therapeutic preparations of IVIg enriched in dimers may be obtained by size exclusion chromatography. Separation by size increases the feasibility of industrial-scale preparation of IVIg with high dimer content that are endowed with high potential immunomodulatory activity in vivo.

Autoantibodies↗
PubMed1994

Anti-CD4 activity of normal human immunoglobulin G for therapeutic use. (Intravenous immunoglobulin, IVIg).

The effects of intravenously administered normal immunoglobulin G (IVIg) in autoimmune diseases are dependent on the ability of IVIg to interact with surface molecules of lymphocytes. In the present study, we demonstrate the presence of anti-CD4 activity in IVIg by showing the ability of IVIg to bind to CD4 and to inhibit CD4-dependent cellular functions. Binding of IVIg to recombinant soluble human CD4 was assessed by ELISA, immunoblotting and real time analysis of complex formation. Anti-CD4 antibodies isolated from IVIg by affinity-chromatography bound to human CD4+ T cells. These anti-CD4 antibodies inhibited proliferative responses in MLR and infection of CD4+ human T cells with HIV. These results indicate that IVIg contains antibodies reactive with human CD4 and that these anti-CD4 antibodies exhibit biological functions. The presence of anti-CD4 antibodies in IVIg may be relevant to the immunoregulatory effects of normal polyspecific immunoglobulin G.

Adjuvants, Immunologic↗
PubMed1994

[Effectiveness of oral versus parenteral iron substitution in autologous blood donors].

OBJECTIVE: Is intravenous iron therapy as efficient as oral iron supplementation in patients undergoing autologous blood donation? DESIGN: Prospective, randomized study. PATIENTS AND SETTING: 30 male and 30 female patients, separated into two groups were examined prior to total hip replacement. INTERVENTIONS: Patients of group O were given 6 x 50 mg Fe2+ aspartate/day orally, and patients of group P were given 0.75 mg/kg BW complex-bound Fe3+ once a week by infusion. In both groups therapy was started two weeks prior to the first donation. The substitution was continued the following six weeks until surgery. Hemoglobin, ferritin plasma concentrations and reticulocytes were monitored. The appearance of unwanted side effects was studied by questionnaire. RESULTS: Hb decreased significantly in both groups. A difference was seen in the reticulocyte count and in the ferritin levels. Here we found a significant increase in group P compared with group O. 40% of the patients who took the iron orally complained about unwanted side effects such as obstipation and diarrhoea, whereas none of the patients of the parenteral group had any complaints. CONCLUSIONS: Stimulation of the erythropoiesis appeared to be more efficient with intravenous iron therapy than with oral iron supplementation. The oral dose has in about 40% unwanted side effects. For this reason a parenteral iron therapy can be considered, but one must be aware that in some cases dangerous anaphylactic reactions could appear.

Administration, Oral↗
PubMed1993

Selection of the expressed B cell repertoire by infusion of normal immunoglobulin G in a patient with autoimmune thyroiditis.

In the present study we have analyzed the changes in the expressed antibody repertoire and in temporal fluctuations of antibody levels in serum that followed infusion of normal IgG (IVIg) in a patient with autoimmune thyroiditis. Administration of IVIg resulted in the stimulation of IgM production, in alterations of expressed antibody activity in serum that could not merely be accounted for by the passive transfer of antibody specificities contained in IVIg, in transient down-regulation of B cells clones expressing a specific disease-related idiotype and in the increase in serum in recipient's autoantibodies specifically reactive with F(ab')2 fragments of IVIg. In addition, infusion of IVIg shifted the pattern of spontaneous fluctuations of autoantibody activities in the patient's serum from a pattern indicative of disconnected events in the immune network to a pattern similar to that which is consistently observed in healthy controls. These results suggest that normal IgG may modulate autoreactivity by selecting expressed antibody repertoire through V region-dependent interactions with antibodies.

Adult↗
PubMed1993

Age-related changes in specificity of human natural autoantibodies to thyroglobulin.

We have analysed the epitopic and idiotypic specificity of thyroglobulin antibodies in infants, young adults, aged subjects and pregnant women in order to evaluate the changes that occur in the autoantibody repertoire with age in physiological situations. No increase in IgG anti-Tg autoreactivity in whole serum and purified IgG from serum was observed with aging. However, IgG from elderly individuals exhibited increased reactivity, as compared to other groups of donors, against particular epitopes commonly recognized by both natural and disease-associated Tg-autoantibodies. The acquisition of a distinct epitopic reactivity in aged individuals suggests that qualitative rather than quantitative criteria could characterize alteration in regulation of the autoreactive B-cell repertoire that occurs with aging. No correlation was observed between the age of the donors and expression of a thyroid disease-associated idiotype (T44 Id) by hTg-autoantibodies. The expression of T44 Id on IgG obtained from serum of a small number of pregnant women may be an effect of the modifications of immune system function in pregnancy, which could lead to increased incidence of autoimmunity during pregnancy or in the post-partum period.

Adult↗
PubMed1993

Polyreactivity is a property of natural and disease-associated human autoantibodies.

Polyreactivity was earlier recognized as a feature of naturally expressed autoantibodies in serum. In the present study, we have compared the reactivity on a panel of self antigens of affinity-purified anti-DNA and anti-thyroglobulin (TG) IgG autoantibodies from the serum of patients with systemic lupus erythematosus (SLE) and autoimmune thyroiditis with their affinity-purified counterparts isolated from the serum of healthy individuals. Anti-DNA autoantibodies exhibited a similar degree of polyreactivity whether originating from patients or from healthy adults. Natural anti-TG autoantibodies were also found to be polyreactive. Anti-TG autoantibodies from patients with Hashimoto's thyroiditis showed little or no polyreactivity. Natural anti-TG autoantibodies were equally polyreactive whether or not they belonged to a fraction of normal IgG that is connected through V regions with other IgG molecules from the same source. These results indicate that polyreactivity of autoantibodies is a feature that does not allow one to distinguish between natural and disease-associated autoantibodies as well as between V-region-connected and unconnected autoantibodies.

Amino Acid Sequence↗
PubMed1992

Origin of anti-idiotypic activity against anti-factor VIII autoantibodies in pools of normal human immunoglobulin G (IVIg).

Therapeutic preparations of polyspecific IgG obtained from plasma pools of a large number of normal donors (IVIg) express anti-idiotypic activity against a wide spectrum of natural and disease-associated autoantibodies. The present study investigated the origin of anti-idiotypic activity against autoantibodies to factor VIII. The neutralizing activity of pools of IgG against patients' anti-factor VIII autoantibodies was not influenced by the presence of individuals with natural anti-factor VIII antibodies among donors contributing to the pool. A higher frequency of neutralizing antibodies against anti-factor VIII autoantibodies was found in aged donors as compared with young adults and in pools of IgG from multiparous women as compared with IgG from random donors. Pooling IgG from several donors synergistically enhanced the inhibitory activity of the pools. Thus, a neutralizing activity against anti-factor VIII autoantibodies was detected in pools of IgG of as few as two to four donors of whom individually tested IgG did not exhibit inhibitory activity against anti-factor VIII autoantibodies. These observations suggest that aged donors and multiparous women may be privileged sources for the anti-idiotypic activity of IVIg against autoantibodies and emphasize that the expression of anti-idiotypic activity in IVIg results from a synergistic participation of anti-idiotypes from each donor contributing to the pool.

Adult↗
PubMed1992

Natural antibodies to factor VIII (anti-hemophilic factor) in healthy individuals.

Spontaneous inhibitors of factor VIII (FVIII) are pathogenic IgG autoantibodies of restricted isotypic heterogeneity found in the plasma of patients presenting with bleeding episodes and low levels of FVIII. We now report the presence of a natural FVIII-neutralizing activity in 85 of 500 plasma samples (17%) from healthy donors. FVIII-inhibitory activity was present in F(ab')2 fragments of purified IgG and was dose-dependent. The titer of anti-FVIII antibodies in normal plasma ranged between 0.4 (threshold of detection) and 2.0 Bethesda units. Anti-FVIII IgG was also detected in normal plasma by using an ELISA. Anti-FVIII antibodies from healthy individuals did not exhibit restricted isotypic heterogeneity. Mean levels of FVIII activity did not differ significantly between individuals with and without detectable anti-FVIII antibodies in plasma. Natural anti-FVIII IgG inhibited FVIII activity in pools of normal plasma and in plasma of certain donors in the pool but did not inhibit FVIII activity in autologous plasma. These observations demonstrate that polyclonal IgG antibodies against procoagulant FVIII are present in healthy individuals. The antibodies are natural IgG autoantibodies and/or antibodies directed against epitopes associated with a so far unidentified allotypic polymorphism of the human FVIII molecule.

Adult↗
PubMed1992

A V region-connected autoreactive subfraction of normal human serum immunoglobulin G.

Mouse and human natural IgM autoantibodies have been shown to be polyreactive and "connected" through V region-dependent interactions. In the present study, we have identified a connected subfraction of normal human serum IgG by using affinity chromatography of F(ab')2 fragments of pooled IgG (IVIg) or of IgG from a single donor on Sepharose-bound F(ab')2 fragments of the same source of IgG. The connected fraction of IgG exhibited a high content of autoantibodies directed against a wide panel of evolutionarily conserved self antigens and of self antigens that may be targets of autoantibodies in autoimmune diseases. Connected IgG also contained higher amounts of antibodies directed against commonly encountered microbial antigens than unfractionated IgG. The connected fraction did not, however, differ from unchromatographed IgG nor from non-connected IgG in its content of antibodies to vaccinal antigens and to distant foreign antigens. Thus, in humans as in mice, connectivity is a prominent feature of autoantibodies. Our observations are suggestive of a tight control by IgG of the expressed autoreactive repertoire in healthy individuals and strengthen the concept that the therapeutic infusion of pooled normal IgG (IVIg) may be effective in autoimmune diseases by bringing to patients normal regulatory components of the immunoglobulin network.

Autoantibodies↗
PubMed1992

Heel-off perturbation during gait initiation: biomechanical analysis using triaxial accelerometry and a force plate.

This study analyzes the movements of the hips, shoulders and of the body center of gravity before and at heel-off, when step execution begins to initiate gait from an upright posture. The heel-off movement was considered as a dynamic perturbation induced by the stepping movement. The experimental paradigm used for studying this perturbation was the single-step movement, in which the initial posture and voluntary movements are identical to those of gait initiation. Data were collected from accelerometer recordings of the triaxial accelerations at the joints of the upper part of the body, and by calculating the triaxial accelerations of the center of gravity using force plate measurements. The resultant vectors were used to establish and compare the magnitude and direction of the accelerations at different joints, and from them, the roles of the pelvis and the scapular girdles with respect to the objectives of the gait movement.

Acceleration↗
PubMed1992

Modulation of autoimmunity by intravenous immune globulin through interaction with the function of the immune/idiotypic network.

Infusion of intravenous immune globulin (IVIG) has resulted in clinical improvement and/or a fall in autoantibody titer in a number of autoimmune diseases in which direct or indirect evidence suggests a pathogenic role for autoantibodies. IVIG may react with disease-associated autoantibodies through idiotypic interactions as shown by the following lines of evidence: (1) inhibition of autoantibody activity in F(ab')2 fragments of patients' IgG by F(ab')2 fragments of IVIG; (2) retention of autoantibodies on affinity columns of Sepharose-bound F(ab')2 fragments of IVIG; and (3) recognition of the same idiotypic determinants on autoantibodies by heterologous anti-idiotypic antibodies and by IVIG. IVIG also interacts with idiotypic determinants on natural autoantibodies as indicated by the binding of monoclonal IgM secreted by Epstein-Barr virus-transformed normal human B cells to F(ab')2 fragments of IVIG and by idiotypic interactions between normal IgG antibodies within the IVIG preparations. Infusion of IVIG into patients with autoimmune diseases alters the kinetic behavior of disease-associated and natural autoantibodies of unrelated specificities. It is our view that IVIG is effective in autoimmune diseases not merely by a passive transfer of suppressive anti-idiotypes, but rather by imposing a normal function on the defective network in autoimmune patients. The intrinsic complexity of IVIG would provide a more logical (physiological) rationale for immunoregulatory therapy of autoimmune disease than idiotype-specific suppression.

Animals↗
PubMed1992

Filtration of buffy coat free red cell concentrates in additive solution.

Leukocyte poor RCC's (LP-RCC) are indicated in chronically transfused patients in order to prevent non-hemolytic transfusion reactions and HLA alloimmunization. In this study buffy coat free red cell concentrates (BCF-RCC) in additive solution (SAG-M) stored for four weeks were leukocyte depleted by filtration with three different filter systems (Erypur Optima (E), Sepacell R500 B (S) and, Pall RC, 50 TM (P)). The BCF-RCC's were prepared using 'bottom and top (BAT)' systems and automatic separation containing about 20% leukocytes and 5% platelets of fresh whole blood. The leukocyte concentration could be reduced to less than 5 x 10(6) per RCC with all filter systems equally: Leukocytes/RCC's: E .58 +/- .94, S .36 +/- .55, P .55 +/- .69 x 10(6). The leukocyte depletion was even in case of filtering two RCC's through one filter (double filtration) efficient enough in order to keep leukocyte contamination below the 'critical immunogenic load for leukocytes (CILL)'. But significant differences concerning the damage of red cells (free hemoglobin, LDH, HBDH) were measured which were even considerable: free hemoglobin E = 3.69 +/- 2.28, S = 1.31 +/- 1.24, P = 3.58 +/- 2.34 g/l. Double filtration was only performed with filter system S showing the best blood compatibility. But the second BCF-RCC also showed considerable hemolysis. Therefore, double filtration of RCC's only seems to be indicated under optimal conditions with blood compatible filters for selected patients. Bed side filtration cannot be recommended because of the risk of hemolysis that makes quality control necessary.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Component Removal↗
PubMed1992

Superiority of gel centrifugation in antibody screening and identification.

We report on the direct comparison of gel centrifugation technique and tube testing for antibody screening (ABS) under controlled routine conditions. 3,000 blood samples were screened for antibodies (AB) by gel centrifugation (ID-System, bromelin 37 degrees C and room temperature, indirect antiglobulin test with LISS) and a sensitive tube test (TT; bromelin two-phase test, 37 degrees C and room temperature, and indirect antiglobulin test with 22% bovine albumin) in parallel. By ID significantly more relevant and potentially hemolytic AB (51 vs. 35 AB/1.7 vs. 1.2%) could be detected: anti-E 4, -C 1, -D 4, -CW 2, -c 2, -Jk(a) 2, -Jk(b) 1. Eleven of these even remained negative in TT when retested with increased sensitivity and taking additional (homozygous) test cells. In addition, naturally occurring but rarely hemolytic AB (35 vs. 23 AB/1.2 vs. 0.8%) were more frequently detectable by ID: anti-Le(a) 6, -Le(b) 2, -P1 6. In contrast, only two AB were only positive in TT: anti-Le(a) 1, -Le(a, b) 1. The main disadvantage of the ID was its frequent positivity (7.7 vs. 4.3%) due to irrelevant cold AB (anti-I, -HI, -H) and unspecific factors. This can be partly reduced by omission of the bromelin test at room temperature (ID 3.0%, TT 1.5%) as the detection of relevant AB is not affected. The frequency of naturally occurring AB was still the same as in TT (0.7%) when bromelin at room temperature was omitted in both techniques. Further advantages of the ID are simplicity, small volumes of sera and reagents, and easy evaluation.

Blood Grouping and Crossmatching↗
PubMed1992

[Filtration of buffy coat-free erythrocyte suspensions in additive solution].

Buffy coat-free red cell concentrates in SAG-M (RCC) were produced by BAT system (leukocyte content 132 x 10(6)/RCC). They were stored for 4 weeks and filtered by Erypur Optima (E), Sepacell R 500 B (S) und PALL RC 50 TM (P). Leukocyte depletion was very effective (E: 0.56 x 10(6)/RCC; S: 0.36 x 10(6)/RCC; P: 0.55 x 10(6)/RCC) but hemolysis was remarkable (E: 301 +/- 195; S: 127 +/- 123; P: 368 +/- 256 mg/RCC). Therefore preparation of two RCC per filter was only acceptable with S. In S and P loss of red cells was tolerable (E: 90.5; S. 41.8; P: 38.2). In contrast, E should be rinsed with sodium chloride at the end of the preparation. In E and S filtration times were short without additional pressure (E: 6.6 min; S: 4.7 min; P: 20.3 min). We conclude from our results that the use of buffy coat-free red cell concentrates in additive solution considerably reduces the problems of filtration, e.g. storage interval, leukocyte reduction, hemolysis, filtration flow. Despite this, bedside filtration is not recommended because quality assurance is necessary.

Blood Component Transfusion↗
PubMed1992

[Production of rejuvenated and stable, leukocyte depleted erythrocyte concentrates using the heated centrifugation method].

We report on an alternative to filtration for the preparation of leukocyte-poor red cell concentrates (LP-RCC). It is based on the method of Schneider. Using RCC with buffy coat it is comparably effective in leukocyte reduction [98.3 +/- 1.0%, (3.7 +/- 2.6) x 10(6) leukocytes] and more effective in platelet reduction (96.9 +/- 2.5%). Addition of PAGGS-M before heating (30 min, 37 degrees C) as well as after preparation significantly reduces hemolysis (free hemoglobin, LDH, HBDH) and improves the quality of the LP-RCC (ATP, 2,3-DPG) during storage for 24 h after preparation. LP-RCCs prepared with PAGGS-M after 6-day storage show still better quality than before preparation and about the same quality as LP-RCCs 24 h after conventional preparation with saline solution. In conclusion, by use of PAGGS-M and sterile docking LP-RCCs of adequate quality for 6-day storage can be prepared, improving the supply of the patients concerned.

Adenine↗