Multiple, heart-cross-reactive epitopes of streptococcal M proteins

We present evidence that a highly purified pepsin extract of type 5 streptococcal M protein (pep M5) contains at least three epitopes that are cross-reactive with sarcolemmal membrane proteins of human myocardium. The tissue-cross-reactive determinants of pep M5 are also partially shared with pep M6 and pep M19. Three rabbits immunized with a single 300 micrograms dose of pep M5 developed significant levels of heart-cross-reactive antibodies, as determined by indirect immunofluorescence tests. All three sera also contained antibodies that cross-reacted with pep M6 and pep M19. The heart tissue--specific antibodies that were eluted from sarcolemmal membranes opsonized types 5, 6, and 19 streptococci, indicating that they were directed against protective M protein epitopes on the surface of virulent organisms. Immunofluorescence inhibition tests, using purified M proteins as soluble inhibitors of heart-cross-reactive antibodies, revealed the number and M protein serotype distribution of the tissue-cross-reactive epitopes. Immunoblot analyses demonstrated the sarcolemmal membrane proteins containing the various cross-reactive antigenic determinants.

Myocarditis and cardiomyopathy

With more widespread application of EMB techniques, a significant percentage of ICCM patients have been found to have lymphocytic myocarditis on biopsy. It is now appreciated that patients with myocarditis may also present with isolated abnormalities of left ventricular diastolic function, dysrhythmias, and/or complaints of chest discomfort with normal coronary angiograms. Epidemiologic and serologic data incriminate a viral etiology underlying many cases of acute myocarditis and ICCM. Although most cases of viral myocarditis appear to resolve without residual left ventricular dysfunction, a small but significant percentage of these patients progress to chronic congestive cardiomyopathy. In the absence of persistent active viral infection in these patients, myocardial damage may be mediated by both cellular and humoral immune mechanisms. The concept of virus-induced immune mediated myocardial damage forms the basis for attempts at immunosuppressive therapy. Whether immunosuppressive therapy alters the natural history of myocarditis is at present unknown and awaits demonstration by a controlled clinical trial.

Lack of cross-reactivity of antibodies to ribosomal preparations from Streptococcus mutans with human heart and kidney antigens

Previous studies have suggested that sera from animals immunized with whole Streptococcus mutans cells may cross-react with human and monkey heart sarcolemmal tissues. In the present study, sera and saliva from rats and rabbits immunized peripherally with ribosomal preparations from S. mutans 6715 (serotype g) or GS-5 (serotype c) were examined for their ability to react with normal human heart sarcolemmal and kidney glomerular tissues by using enzyme-linked immunosorbent and immunofluorescence assays. The results showed that antibodies to serotype g and c ribosomal preparations do not react with either the human heart or renal antigens. Sera from mice immunized with human heart tissue and from a patient with a high anti-streptolysin O titer reacted strongly with human heart sarcolemmal and kidney glomerular tissues. These data indicated that ribosomal preparations from S. mutans lack the putative human heart cross-reactive determinant and suggest that the use of an S. mutans ribosomal vaccine against dental caries may not be pathogenic to human heart or renal tissues.

Murine monoclonal antibodies reactive with human heart and group A streptococcal membrane antigens

Ten selected murine hybridoma cell lines that produce monoclonal antibodies against M type 5 Streptococcus pyogenes and human heart antigen were isolated. All of the monoclonal antibodies studied were determined to be the immunoglobulin M isotype. The antibodies were characterized on the basis of their reactions with Triton X-100-extracted whole human heart antigens, sodium dodecyl sulfate-extracted sarcolemmal antigens, and whole streptococci or their membranes. Enzyme-linked immunosorbent assays and Western immunoblotting techniques were used to compare the reactivity of the monoclonal antibodies. All 10 of the antibodies were first selected for their reactivity with Triton X-100-extracted heart antigens and whole group A, M type 5 streptococci. These antibodies were then divided into two categories: strong reactors or weak reactors with human sarcolemmal and streptococcal membranes. Among the strong reactors, two different types of monoclonal antibodies were observed on the basis of their immunobanding patterns with sarcolemmal and streptococcal membranes on Western blots. Monoclonal antibodies that were strong reactors with sarcolemmal and group A streptococcal membrane antigen were directed against a determinant on a family of proteins. The major reactants of sarcolemmal extracts were high-molecular-weight proteins near 200,000. Some monoclonal antibodies demonstrated more specificity for the heart than did others when reacted with separated Triton X-100-extracted tissue antigens from the heart, kidney, and skeletal muscle. One of the monoclonal antibodies that reacted with group A streptococci reacted with a Triton X-100-extracted heart antigen ca. 40,000 daltons in size. None of these monoclonal antibodies opsonized type 5 Streptococcus pyogenes, and in enzyme-linked immunosorbent assays most of the antibodies were found to react to a lesser degree with other groups of streptococci. Monoclonal antibody was used to probe normal and rheumatic sarcolemma for differences in reactivity. Although the rheumatic heart reacted more intensely, no major differences between the immunobanding patterns of normal and rheumatic hearts were observed.

[The post-pericardiotomy syndrome. Incidence of clinical and immunological changes]

We report the clinical and serological studies in patients who underwent pericardiotomy. Seventy three per cent of them developed antisarcolemma antibodies 4 weeks after surgery, and a third of them also had antimitochondrial antibodies. However, clinical post-pericardiotomy syndrome was rare; only 7% of the patients fulfilled the criteria for this diagnosis. Although immune responses against tissue antigens are frequent as a consequence of surgical trauma, the clinical manifestations are rare.

Immunocytochemical localization of the mammalian voltage-dependent sodium channel using polyclonal antibodies against the purified protein

Antibodies were raised in rabbits against the purified voltage-dependent sodium channel from rat skeletal muscle sarcolemma. The resultant antiserum reacted with the purified channel in a solid-phase radioimmunoassay and precipitated the sodium channel from a crude mixture of solubilized membrane proteins. Crude membrane proteins separated according to size under nondenaturing conditions by chromatography on Sepharose CL-6B contained a single peak of immunoreactivity that coincided with the native channel. On immunoblots of sarcolemmal membrane proteins, the antiserum reacted predominantly with a diffuse high molecular weight band that was comparable in migratory characteristics to the large glycoprotein subunit of the purified channel. Using immunocytochemical techniques, binding of this polyclonal antiserum was localized to the surface membrane of rat skeletal muscle. This staining was specifically blocked by pre-incubation of the antiserum with the purified channel protein. The antiserum also stained the surface membrane of rat cardiac muscle and the nodes of Ranvier in rat peripheral nerve. Species cross-reactivity was seen with mouse, human, and guinea pig skeletal muscle while chicken, rabbit, and frog muscle was not stained. The antiserum also reacted with the surface membranes of fetal rat muscle in tissue culture. These results indicate that sodium channels in adult mammalian skeletal muscle, cardiac muscle, and peripheral nerve and in fetal muscle in culture all share common antigenic determinants. The antiserum should prove useful for topographical studies of sodium channel distribution in these tissues.

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.

Diagnostic relevance of humoral and cytotoxic immune reactions in primary and secondary dilated cardiomyopathy

Circulating muscle-specific antimyolemmal antibodies (AMLAs) were found in 18 of 61 patients with secondary dilated cardiomyopathy (DC). All 18 patients had clinical or histologic evidence of previous perimyocarditis. AMLAs were found both in patients' serum samples and bound to the sarcolemmal sheath of the autologous myocardial biopsy specimen. Only AMLAs in postmyocardiac DC induced cytolysis of vital cardiocytes in the presence of complement, whereas hepatocytes remained unaffected. Titers of AMLAs correlated with the degree of cardiocytolysis. In contrast, antiinterfibrillary antibodies were found in 49% patients with primary DC (n = 79) and in 61% of patients (n = 30) with alcoholic DC. The incidence of antifibrillary antibodies of the antimyosin type was 23 and 24%, respectively. Incidence of both antibodies increased according to the severity assessed by New York Heart Association functional classes. Circulating immune complexes assayed by a new Clq-solid phase fluorometric assay were present in 30% of patients with postmyocarditic DC only. Lymphocyte-mediated cytotoxicity against heterologous cardiac target cells (K-cell activity) was measured in 33% of patients each with primary and secondary alcoholic DC but not postmyocarditic DC. There were no blocking factors in primary but were some in alcoholic heart disease.

Monoclonal antibodies to human leucocyte antigens in polymyositis and muscular dystrophy

Biopsy specimens from patients with treated or untreated polymyositis and muscular dystrophy controls were examined by indirect immunoperoxidase staining with a panel of monoclonal antibodies to human leucocyte antigens. In untreated polymyositis, helper/inducer T cells were the predominant T cell subset. In treated cases few T cells were seen. Overall, few T cells were seen in dystrophic cases, most infiltrating cells being dendritic and lacking T cell antigens. Staining of sarcolemma with anti-HLA class 1 antibody is weak or negative except in areas adjacent to infiltrating leucocytes or where muscle fibre damage is apparent.

[Effect of streptococcal products in the induction of antibodies against cardiac sarcolemma]

It has been pointed out in rheumatic fever that the extracellular products of streptococcus (EPS) induce an immune response capable of producing autoimmunity against cardiac structures. In an experimental model in rats, the possibility that EPS facilitates the production of antisarcolemma antibodies was analyzed by injecting the animals with EPS, or simultaneously with EPS and human heart sarcolemma (HHS). The rat sera was analyzed by microdouble immunodiffusion against EPS, HHS or a mixture of both, the rats immunized with HHS or with EPS and HHS produced anti-HHS antibodies. The average of precipitation bands increased with the number of immunizations. Under the experimental conditions used, the humoral immune response against HHS was not modified by EPS and also EPS alone did not induce antibodies against sarcolemma. The synthesis of antibodies to EPS was very low or Null. The antiestreptolysin-O levels were low during the immunization period. A minimal inspecific myocarditis with lymphocytic inflammatory infiltrate was induced. The humoral immune response against cardiac sarcolemma and against the extracellular products of streptococcus was similar in the groups of rats studied, independently of sex, weight, age, dose, inoculation method or immunization time in accordance with schemes used in this work.

Immune reactions in infective endocarditis. I. Clinical data and diagnostic relevance of antimyocardial antibodies

Clinical data from 72 patients with infective endocarditis (41 with defined pathogen, 31 with no pathogen isolated) were analyzed with respect to the diagnostic relevance of immunologic parameters. In our patients from a rural area, no significant changes in the epidemiology and pathogenesis of infective endocarditis were observed. Antiendocardial and antisarcolemmal (ASA) antibodies were demonstrated in 60% to 100% of cases. Their frequency depended on the endocarditic pathogen and on the clinical course: in subacute or chronic endocarditis these antibodies were found regularly, in acute lethal cases their occurrence was diminished. Whereas antiendocardial antibodies are diagnostic markers of endocarditis, ASA and antimyolemmal antibodies in particular most likely indicate myocardial involvement in endocarditis. Only complement fixing antimyolemmal antibodies induced cytolysis of vital, adult, heterologous cardiac cells. Our data suggest that antibody-mediated cytolysis in vitro may also play a pathogenetic role in vivo.

Immune reactions in tuberculous and chronic constrictive pericarditis. Clinical data and diagnostic significance of antimyocardial antibodies

Humoral immune reactions were analyzed in 12 patients with exudative tuberculous pericarditis, 10 patients with constrictive pericarditis due to former tuberculosis, 10 patients with viral pericarditis, 20 patients with pulmonary tuberculosis, and 98 healthy donors. Pericarditis occurred in 12.5% of the patients with tuberculosis, whereas the incidence of tuberculosis in the 149 patients with pericarditis was 8%. Repeated pericardial puncture and pericardial effusions of greater than 500 ml with impending cardiac tamponade had to be performed in 4 patients. Clinical data indicated probable myocardial involvement in 4 of 12 patients. Antimyolemmal antibodies, which are a muscle-specific subtype of antisarcolemmal antibodies, were found in all patients with exudative tuberculous pericarditis and viral perimyocarditis, in only 1 of 12 patients with constrictive pericarditis, and in no patients with pulmonary tuberculosis. Antifibrillary antibodies--primarily of the antimyosin type--were missed in patients with viral heart disease but were demonstrated in 75% of patients with tuberculous pericarditis. Only sera with complement-fixing antimyolemmal antibodies of the IgG type in titers greater than 1:40 induced cytolysis of vital adult heterologous cardiocytes isolated and enriched by silica sol gradient centrifugation. These findings suggest not only that antimyolemmal antibodies are diagnostic indicators of perimyocardial involvement in tuberculous pericarditis, but also that they may play a significant role in its pathogenesis.

Protective antigenic determinant of streptococcal M protein shared with sarcolemmal membrane protein of human heart

We present definitive evidence that at least one protective antigenic determinant on type 5 M protein of group A streptococci evokes antibody that is cross-reactive with human heart tissue. One of nine rabbits immunized with a peptide fragment of type 5 M protein (pep M5) produced antibody that cross-reacted by immunofluorescence with sarcolemmal membranes of human heart. The cross-reactive antibody could be removed by absorbing the antiserum with sarcolemmal membranes, types 5 and 19 streptococci, or their pepsin-extracted M proteins, but with no other serotypes tested. Although each of the pep M5 immune sera was opsonic for type 5 streptococci, only the heart-reactive antiserum opsonized type 19 streptococci. The opsonization of type 19 streptococci was abolished by absorbing the antiserum with sarcolemmal membranes isolated from human heart tissue. Purified heart-reactive antibodies eluted from sarcolemmal membranes opsonized both types 5 and 19 streptococci, indicating that the heart cross-reactive determinant of type 5 M protein is cross-protective. The cross-reactive antigen was purified by affinity chromatography from detergent extracts of sarcolemmal membranes and determined to be a complex protein composed of four subunits apparently linked by disulfide bonds.

Complement activation in muscle fiber necrosis: demonstration of the membrane attack complex of complement in necrotic fibers

The membranolytic C5b-9 complement membrane attach complex (MAC) is assembled after activation of either the classic or the alternative complement pathway. The quaternary configuration of the MAC macromolecule presents neoantigenic determinants not present on precursor molecules. Consequently, antibodies specific for these neoantigen(s) do not detect nonspecifically bound native complement precursors of MAC. By means of antibodies rendered specific for MAC neoantigen(s), MAC was localized by the immunoperoxidase reaction in cryostat sections of human muscle. In 66 biopsy specimens containing necrotic muscle fibers (Duchenne dystrophy, 13; other dystrophies, 15; inflammatory myopathies, 31; miscellaneous myopathies, 7) all of the necrotic fibers reacted for MAC neoantigen(s). C3 and C9 were also consistently localized in necrotic fibers, but localization of C1q, C4, and IgG was variable and often did not exceed background staining. None of the nonnecrotic fibers reacted for immunoglobulin or complement. Detection of MAC neoantigen(s) in necrotic fibers in a wide variety of muscle disease unambiguously shows that (1) the lytic complement pathway is consistently activated and participates in muscles fiber necrosis in vivo, and (2) complement reaction products are generated than can stimulate cellular infiltration and phagocytosis of the necrotic fiber. The findings also suggest that cell necrosis in general may involve participation of complement.

Pathologic features of muscle in systemic lupus erythematosus: a biopsy series with comparative clinical and immunopathologic observations

Clinical evidence of skeletal muscle involvement is frequent in systemic lupus erythematosus (SLE). In order to characterize the manifestations of SLE in skeletal muscle, a biopsy series on 19 patients with SLE was studied in terms of the histologic, histochemical, and direct immunofluorescent features of skeletal muscle. The results were correlated with clinical and laboratory data. The histologic spectrum included inflammatory myopathy, vasculitis, perifascicular atrophy, and neurogenic atrophy. Histochemical examination revealed type I fiber predominance in 44 per cent of patients and selective type II fiber atrophy in 33 per cent. Direct immunofluorescent examination of skeletal muscle biopsy specimens revealed immunoglobulin and complement deposition in vessel walls, in sarcolemmal basement-membrane areas, and within non-necrotic muscle fibers. The histologic, histochemical, and immunochemical findings are correlated with the findings in other organ systems.

Diagnostic relevance of humoral and cell-mediated immune reactions in patients with acute viral myocarditis

Sera of 177 patients with acute myocarditis (10 coxsackie B 3/4, four influenza, four mumps, 15 cytomegalovirus, 144 undefined) were tested by indirect immunofluorescence for autoantibodies against heart and skeletal muscle and vital or air-dried adult cardiocytes. Antibody-dependent cytolysis, lymphocytotoxicity and antibody-dependent cellular lymphocytotoxicity were assessed using viral adult rat cardiocytes as target cells. Muscle-specific anti-sarcolemmal antibodies of the anti-myolemmal type--often associated with non-organ-specific anti-endothelial antibodies--were demonstrated in nine out of 10 patients with coxsackie B, in all patients with influenza and mumps and in 65 out of 144 patients with undefined myocarditis. In contrast, 13 out of 15 patients with cytomegalovirus myocarditis lacked anti-sarcolemmal antibodies but had low titre anti-inter fibrillary antibodies instead. In the presence of complement, anti-myolemmal antibodies induced cytolysis of vital cardiocytes, whereas hepatocytes remained unaffected. Titres of anti-myolemmal antibodies correlated with the degree of cardiocytolysis. The anti-myolemmal immunofluorescent pattern and the cytolytic serum activity could be absorbed with the respective viral antigens suggesting that these antibodies cross-react with moieties of the virus itself and may be both diagnostic and aetiological markers in acute viral myocarditis. Lymphocyte-mediated cytotoxicity against heterologous cardiac target cells could not be observed in our patients with myocarditis of proven viral aetiology. However, lymphocyte-mediated cytotoxicity was demonstrated in 10 ASA-positive and one ASA-negative patient with myocarditis of unknown origin. ASA-positive sera blocked lymphocytotoxicity in three of these patients.

Assessment of antibody mediated cytolysis of adult cardiocytes isolated by centrifugation in a continuous gradient of Percoll 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.

[Antibodies to myocardial muscle fiber sarcolemmic antigens in rheumatism and other heart diseases]

The work discusses the results of studying by indirect immunofluorescence and the passive hemagglutination test antibodies to sacolemma antigens of myocardial muscle fiber in patients with rheumatic fever as compared to those in patients with affection of myocardium of nonrheumatic origin. The frequency of the detection of antibodies to sarcolemma antigens in sera of patients with rheumatic fever by immunofluorescence correlates with the activity of the process. No differences were revealed in the frequency of detection of antibodies reacting with sarcolemma in rheumatic fever and in other heart diseases in the active phase. Antibodies to sarcolemma antigens contained in HCL-extracts from human myocardium preparations, which are detected in the passive hemagglutination test are revealed significantly more often in sera of patients with rheumatic fever. Control experiments with IgG fractions obtained from whole sera were conducted to remove any possible nonspesific reactions of tissue extracts with the sera tested.

Binding of streptococcal antigens to muscle tissue in vitro

Antigens extracted from cells of Streptococcus pyogenes T6 and Streptococcus mutans strains AHT, BHT, 10449, OMZ175, and K1R adsorbed to the sarcolemmal sheath of cardiac muscle cells in vitro. Similar preparations from S. salivarius, S. sanguis, Staphylococcus aureus, and Lactobacillus casei had weak or negligible tissue-binding activity. Tissue-bound bacterial antigens were detected with homologous rabbit antisera with both indirect immunofluorescence tests and an indirect radioimmunoassay. Serological cross-reactivity was observed between the tissue-binding factors of S. pyogenes and S. mutans cells but not between the bacteria and muscle tissue. In a comparative study of extraction procedures, the greatest yield of tissue-binding factors was obtained from group A streptococci by cell disruption in buffer at 4 degrees C. Hot aqueous phenol and hot water extracts were inactive. Antibodies specific for the tissue-binding factor(s) were readily adsorbed from rabbit anti-S. pyogenes serum by a preparation of isolated cytoplasmic membranes but not by a suspension of cell wall fragments. The heart-binding component of S. pyogenes cell extracts was inactivated by protease digestion and heat treatment and to a lesser extent by periodic acid oxidation. The capacity of heart cell components to adsorb streptococcal antigens was reduced by protease treatment but not by the action of neuraminidase, hyaluronidase, organic solvents, or detergents.

Clinical significance of immunopathological findings in patients with post-pericardiotomy syndrome. I. Relevance of antibody pattern

Sera from sixty-five patients were collected before and after cardiac surgery to determine striated muscle antibodies (anti-heart and anti-skeletal), non-organ-specific antibodies, immunoglobulin and complement levels. According to the clinical features of pericarditis, fever and leucocytosis, patients were divided into three groups: (1) complete post-pericardotomy syndrome (PPS) (n = 19) with all three symptoms; (2) incomplete PPS with two symptoms (n = 18); and (3) no PPS with one or no symtpoms (n = 28). Almost all the patients with complete PPS, two thirds of the patients with incomplete PPS and one third of the patients with no PPS showed striated muscle antibodies. Anti-sarcolemmal antibodies predominated.

In patients with complete PPS, antibodies persisted beyond the fourth post-operative week and correlated well with symptoms. An even better correlation with the syndrome could be obtained by including the post-operative occurrence of anti-endothelial (AEA), smooth muscle (SMA), the pre- and post-operative frequency of antinuclear antibodies (ANA) and the increase in immunoglobulin concentrations after surgery in an immunological grading system. These criteria permitted a redistribution of the nineteen patients with an incomplete PPS: fourteen were immunologically positive for a PPS. Although autoantibodies are predominantly associated with PPS, their role in the pathogenesis of the syndrome is not clear. The complementary influence of surgical and non-surgical factors, such as the degree of myocardial damage, the time of ischemia during the operation and a possible viral infection by blood transfusion, is analysed.