Bernhard Maisch

Assessment of antibody mediated cytolysis of adult cardiocytes isolated by centrifugation in a continuous gradient of percollTM in patients with acute myocarditis

Principal objections to conventional cytotoxicity assays in cardiac disease with myocytes as target cells are the use of fetal or neonatal myocardium, the cell-membrane of which does not express all antigenic determinants, and the use of trypsin as enzyme for isolation of the cells, since this alters the myolemmal membrane considerably. An improved and rapid procedure for the isolation of intact adult cardiocytes with collaggenase was developed. by means of a performed continuous self-generating silica sol and gradient centrifugation average enrichment of 81% vital myocytes was achieved by a single isopycnic procedure. The yield was improved to 94 +/- 3% vital cells by identical second centrifugation. Cardiocytes isolated by this method were used as target cells in an assay measuring the cytolytic activity of antibodies in the presence of complement: sera of patients suffering from acute viral myocarditis (Coxsackie B- and influenza-virus) with complement fixing antisacrolemmal antibodies (ASA) of the IgG- and IgM-type showed significant cardiocytolysis. ASA are postulated to play a role in the pathogenesis of acute Coxsackie B- and influenza-virus myocarditis.

Immune reactions in infective endocarditis. II. Relevance of circulating immune complexes, serum inhibition factors, lymphocytotoxic reactions, and antibody-dependent cellular cytotoxicity against cardiac target cells

Circulating immune complexes (IC) were detected in 35 out of 41 patients (85%) with infective endocarditis of known bacterial origin in contrast to only 9 out of 20 patients (45%) with endocarditis but negative blood cultures (p less than 0.05). Peak IC levels of 33.25 +/- 24.33 micrograms/ml in the early period fell significantly to 8.38 +/- 13.37 micrograms/ml after antibiotic treatment (p less than 0.001). High levels of IC coincided with relative hypocomplementemia. Erythrocyturia was observed in 51 of 58 IC-positive patients demonstrating peripheral sequelae of circulating IC. Incidence and concentrations of IC correlated neither with the mere presence of the rheumatoid factor nor with the titers of antimyolemmal antibodies, nor with antibody mediated cytolysis in the presence of complement. Serum inhibition factors (SIF) and E-rosette inhibitory factors (RIF) were not demonstrated, indicating that IC in endocarditis do not suppress phytohemagglutinin-induced lymphocyte proliferation or the E-rosetting of T cells. Significant lymphocytotoxicity against heterologous cardiac target cells without serum (LC) could be demonstrated in 11 out of 23 patients (48%) with endocarditis as compared to its absence in controls (n = 33, p less than 0.01). In assays of antibody-dependent cellular cytotoxicity (ADCC), either enhancement or blocking of lymphocytotoxicity by autologous serum or both was observed. The modulation of lymphocytotoxicity was most likely due to antimyolemmal antibodies, to IC, or to both, although effects of other serum factors cannot be ruled out completely.

Immunologic regulator and effector functions in perimyocarditis, postmyocarditic heart muscle disease and dilated cardiomyopathy

In acute perimyocarditis we found that OKIAI-positive cells were increased, and in dilated cardiomyopathy OKMI-positive cells were increased. No significant alteration in suppressor T cell activity was observed in our patients with either disease. The characteristic immunofluorescent pattern in carditis and postmyocarditic heart disease is the presence of antimyolemmal antibodies with intact rat and human cardiocytes in titers of 1:40-1:320 as antigens. The antimyolemmal fluorescence can be absorbed with the respective causative virus in Coxsackie B, influenza, mumps and EBV-myocarditis, indicating that the antibodies are a cross-reactive. AMLA-positive sera induce cytolysis of vital rat cardiocytes in vitro, suggesting that the antibodies are of pathogenetic relevance. Cytolytic serum activity could be absorbed out with the respective virus. Immunohistologic specimens obtained from patients with carditis demonstrate the fixation of IgG and IgM antibodies; IgG antibodies also occur in dilated cardiomyopathy and coronary artery disease. In dilated postmyocarditic heart disease both antimyolemmal fluorescence and cytolytic activity are preserved at a lower level when compared to carditis. These antibodies can also fix complement. In the acute phase of carditis circulating immune complexes can be demonstrated. Cellular effector mechanisms against vital cardiocytes were maintained or even slightly enhanced in carditis, postmyocarditic and primary dilated cardiomyopathy. In vitro NK cell activity against K 562, however, was decreased. This is compatible with a sustained target-specific cytotoxicity whereas reduced NK cell activity may indicate impairment of this effector organ.

Drug withdrawal and rebound hypertension: Differential action of the central antihypertensive drugs moxonidine and clonidine

SummaryTo examine the antihypertensive action of the centrally acting antiadrenergic drugs moxonidine and clonidine, systolic and diastolic blood pressure as well as heart rate were monitored by radio telemetry in spontaneously hypertensive rats (SHR) with established high blood pressure. Increasing doses were administered with regular rat chow for 6–8 day periods. Moxonidine reduced (p<0.05) diastolic blood pressure at a dose of 8 mg/kg/day and systolic blood pressure at 13 mg/kg/day. Heart rate was reduced during high activity of rats corresponding to an antitachycardiac action. After withdrawal of 18 mg/kg administered for only 1 day, blood pressure returned to pretreatment values within 8 days. Clonidine reduced systolic and diastolic blood pressure at 0.3 mg/kg/day. At 0.8 and 1.3 mg/kg/day, systolic blood pressure reduction was less pronounced, although heart rate was reduced further, reaching values that were below those of untreated sleeping rats. When 1.3 mg/kg/day clonidine was discontinued, systolic as well as diastolic blood pressure increased above pretreatment values within 1 day. A rebound was also observed in heart rate, which increased by 150 beats/min. A comparable rebound in blood pressure was observed after withdrawal of 0.3 mg/kg/day. Since a blood pressure rebound occured also after withdrawal of 0.3 mg/kg/day clonidine in normotensive rats, the rebound phenomenon was independent of the presence of high blood pressure. No blood pressure rebound was observed when moxonidine (8 mg/kg/day) was administered (chow or gavage) in normotensive rats. These findings in unanesthetized undisturbed rats demonstrate distinct differences in the mode of action of moxonidine and clonidine, which can be accounted for by specific interactions of moxonidine with imidazoline I1-receptors, whereas clonidine would interact not only with I1-receptors but also with alpha2-adrenoceptors, and most probably also with the vagal activity. In view of our previous studies demonstrating a rise in blood pressure and heart rate after a hypercaloric dietary intake, the selective I1-receptor agonist moxonidine appears particularly appropriate for treating overweight hypertension associated with an enhanced sympathetic outflow of the brain. Of importance in this respect is that a moxonidine-induced reduction in sympathetic outflow was not associated with a gain in body weight but resulted in reduced caloric intake.

Dietary linolenic acid-mediated increase in vascular prostacyclin formation

To define vascular effects of an enhanced dietary α-linolenic acid intake, 28 spontaneously hypertensive rats were fed a 3% sunflowerseed oil (44% linoleic acid) diet; in 3 groups (7 rats each), the diet was supplemented with 1, 2.5 or 5% linseed oil containing 62% α-linolenic acid. α-Linolenic acid was incorporated up to 12% in the aorta of the 5% linseed oil group. The eicosapentaenoic acid content was not significantly increased. The content of arachidonic acid and docosatetraenoic acid was moderately reduced in rats fed 5% linseed oil. The generation of 6-keto-PGF1α (degradation product of prostacyclin) assessed by HPLC/electrochemical detection was, however, markedly increased (p < 0.05) in rats fed 2.5 and 5% linseed oil. The minor prostanoids TXB2, PGE2 and PGF2α were not significantly altered. The high systolic and diastolic blood pressure of SHR monitored by radio telemetry was more effectively reduced (p < 0.05) in the light, i.e. sleep, cycle. An increased prostacyclin formation and lowered vascular arachidonic acid content associated with enhanced dietary α-linolenic acid intake would thus be expected to prove beneficial in the prevention of vascular disorders.

Myasthenia gravis: Overlap with ‘polyendocrine’ autoimmunity

Summary81 patients with spontaneously acquired myasthenia gravis (MG) were investigated for the presence of autoimmune (AI) diseases and their sera were tested for a range of organ-specific autoantibodies. 77 of the patients were HLA-phenotyped. Antibody titres to acetylcholine receptors (AChR) were higher in non-thymomatous patients who possessed HLA-B8 (p<0.05) and/or -DR3 (p<0.05) as compared to patients lacking these HLA antigens. 3 out of 20 (15%) patients with ocular MG, 7/23 (30%) with generalized MG of early onset, 11/23 (48%) generalized MG of late onset and 5/14 (35%) patients with thymoma had either overt AI diseases or significant titres of organ-specific autoantibodies suggesting subclinical AI disease. In ocular MG, low titres and an infrequent finding of antibodies to AChR (32%) as well as the low prevalence of associated autoantibodies and AI diseases indicate that this subgroup of MG consists of patients with restricted AI reactivity. HLA-B8and -DR3 were present in all the patients with associated AI disorders in the young onset group but in none of the patients with old age of onset. In the young group, 6 out of 7 patients with associated AI conditions were women whereas the sex ratio was about equal in the older cases in both, patients with and without associated AI diseases or autoantibodies. We conclude from these observations that ageing provides conditions that allow the breakdown of self tolerance. The simultaneous presence of HLA B8, DR3 and female sex provide important additional factors for early expression of MG.

Surface antigens of adult heart cells and their use in diagnosis.

The mapping of immunologically relevant epitopes of the myolemma, sarcolemma and endothelium are prerequisites for the analysis of humoral and cellular effector mechanisms. Mapping was carried out by monospecific anticollagen and anticytoskeleton antibodies, monoclonal antibodies against the surface of white blood cells and by lectins which bind to specific sugars on membranes. Characteristic differences between myolemma, sarcolemma and endothelium could be defined. In patients with perimyocarditis and postmyocarditic cardiomyopathy antibodies directed against the myolemma were detected. They are cytolytic in the presence of complement and cross-reactive to the causative viral agents. Furthermore lymphocytotoxic effector mechanisms could be demonstrated in vitro in one third of patients with AMLA-negative primary dilated cardiomyopathy.

Immunological parameters in patients with congestive cardiomyopathy@@@Immunologische Parameter bei Patienten mit kongestiver Kardiomyopathie

Cardiomyopathies comprise those myocardial diseases that are not caused by coronary heart disease or mechanical overload. We studied 83 patients with cardiomyopathies, who were classified according to Goodwin (1970) (1): 1) 55 patients had congestive cardiomyopathy (COCM). 34 of them were of the primary, 21 of the secondary alcoholic type. 2) 28 patients had hypertrophic cardiomyopathy with or without obstruction (HOCM).

Dehnungs- und entdehnungsinduzierte Änderungen im passiven und aktiven Verhalten des isolierten Katzenpapillarmuskels

SummaryIn the isolated cat papillary muscle a rapid change in length induces a viscoelastic process of relaxation, during which the diastolic tension attains its new equilibrium after a delay. Its time course may be approximated both after stretching and releasing by a total of four exponential functions being marked by highly diverse time constants.During the stretch-induced relaxation phase the isometrically active papillary muscle shows a marked increase in mechanogram amplitudes, which is preceded in the first seconds by a short-term decrease. An opposite behaviour is to be recorded after abrupt releases. The mechanograms of the stationary state prove to be exclusively a function of the degree of stretch, while the contractions in the early relaxation phases are dependent on the speed, direction and scale of the preceding change in length. The higher the stretching step chosen, the more clearly reduced are the mechanogram amplitudes of the early relaxation phase in comparison to the stationary state. This applies especially right of the optimum of force-development and contradicts a viscoelastic interpretation of the systolic phenomena in the poststretch phase. The findings after abrupt stretching point to either an initial decrease of amplitude or to a delayed approach of the contractions to their stationary state. Stretch-induced changes in the time course of the action potentials would constitute an adequate basis for the interpretation of these phenomena.ZusammenfassungEine schnelle Längenänderung löst am isolierten Katzenpapillarmuskel einen viskoelastischen Relaxationsprozeß aus, in dessen Verlauf die diastolische Kraft verzögert ihrem neuen Gleichgewichtswert zustrebt. Ihr Zeitverlauf läßt sich sowohl nach Dehnung als auch nach Entdehnung durch eine Summe von wenigstens vier Exponentialfunktionen approximieren, die durch sehr unterschiedliche Zeitkonstanten ausgezeichnet sind.Der isometrisch tätige Papillarmuskel zeigt im Verlauf einer dehnungsinduzierten Relaxationsphase einen ausgeprägten Anstieg der Mechanogrammamplituden, dem in den ersten Sekunden eine kurzfristige Abnahme vorausgeht. Nach abrupter Entdehnung mißt man ein spiegelbildliches Verhalten. Die Mechanogramme des stationären Zustands erweisen sich ausschließlich als Funktion des Dehnungsgrades, während die Kontraktionen in den Relaxationsfrühphasen von Geschwindigkeit, Richtung und Ausmaß der vorausgegangenen Längenänderung abhängen. Je höher ein Dehnungssprung gewählt wird, um so deutlicher sind die Mechanogrammamplituden der Relaxationsfrühphase gegenüber dem stationären Zustand reduziert. Dies gilt insbesondere rechts des Optimums der Kraftentwicklung, was einer viskoelastischen Deutung der systolischen Phänomene in der Nachdehnungsphase widerspricht. Die Befunde nach abrupter Dehnung sprechen entweder für eine initiale Amplitudenminderung oder für eine verzögerte Annäherung der Kontraktionen an ihren stationären Zustand. Dehnungsbedingte Änderungen im formalen Verlauf der Aktionspotentiale würden eine hinreichende Basis für die Interpretation dieser Phänomene bilden.

Humoral Immune Response in Viral Myocarditis

Viral and postviral autoimmune myocarditis are important causes of cardiac morbidity. The spectrum of the infectious agents varies with geographic region, age of the patient, application of different therapeutic procedures, and additional diseases. In many cases, dilated cardiomyopathy may be the consequence of a secondary immunopathogenesis after viral disease or unknown agents. This chapter deals with our knowledge of the humoral immune response in the myocarditis-perimyocarditis syndrome and its interplay with the viral agents and with the immune system. A more detailed definition of terms is used for the histologic and immunologic diagnosis of myocarditis.