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

Established and novel pathophysiological mechanisms of pericardial injury and constrictive pericarditis

This review article aims to: (1) discern from the literature the immune and inflammatory processes occurring in the pericardium following injury; and (2) to delve into the molecular mechanisms which may play a role in the progression to constrictive pericarditis. Pericarditis arises as a result of a wide spectrum of pathologies of both infectious and non-infectious aetiology, which lead to various degrees of fibrogenesis. Current understanding of the sequence of molecular events leading to pathological manifestations of constrictive pericarditis is poor. The identification of key mechanisms and pathways common to most fibrotic events in the pericardium can aid in the design and development of novel interventions for the prevention and management of constriction. We have identified through this review various cellular events and signalling cascades which are likely to contribute to the pathological fibrotic phenotype. An initial classical pattern of inflammation arises as a result of insult to the pericardium and can exacerbate into an exaggerated or prolonged inflammatory state. Whilst the implication of major drivers of inflammation and fibrosis such as tumour necrosis factor and transforming growth factor β were foreseeable, the identification of pericardial deregulation of other mediators (basic fibroblast growth factor, galectin-3 and the tetrapeptide Ac-SDKP) provides important avenues for further research.

Anticardiac Antibodies in Patients with Chronic Pericardial Effusion

Objectives. Chronic pericardial effusion may be challenging in terms of diagnosis and treatment. Specific laboratory parameters predicting the frequency and severity of recurrences after initial drainage of pericardial effusion are lacking. Materials and Methods. Pericardial fluid (PF) and serum (SE) samples from 30 patients with chronic pericardial effusion (PE) who underwent pericardiocentesis and pericardioscopically guided pericardial biopsy were compared with SE and PF samples from 26 control patients. The levels of antimyolemmal (AMLA) and antifibrillary antibodies (AFA) in PE and SE from patients with pericardial effusion as well as PF and SE from controls were determined and compared. Results. AMLAs and AFAs in PF and SE were significantly higher in patients with chronic pericardial effusion than in the control group (AMLAs: p = 0,01 for PF and p = 0,004 for serum; AFAs: p < 0,001 for PF and p = 0,003 for serum). Patients with recurrence of PE within 3 months after pericardiocentesis had significantly higher levels of AMLAs in SE (p = 0,029) than patients without recurrence of PE. Conclusions. The identification of elevated anticardiac antibodies in PE and SE indicates increased immunological reactivity in chronic pericardial effusion. High titer serum levels of AMLAs also correlate with recurrence of pericardial effusion.

Tuberculous pericarditis with and without HIV

The human immunodeficiency virus (HIV) has altered the epidemiology, clinical manifestations, treatment considerations and natural history of tuberculous (TB) pericarditis with significant implications for clinicians. The caseload of TB pericarditis has risen sharply in TB endemic areas of the world where co-infection with HIV is common. Furthermore, TB is the cause in greater than 85 % of cases of pericardial effusion in HIV-infected cohorts. In the absence of HIV, the morbidity of TB pericarditis is primarily related to the ferocity of the immune response to TB antigens within the pericardium. In patients with HIV, because TB pericarditis more often occurs as part of a disseminated process, the infection itself has a greater impact on the morbidity and mortality. HIV-associated TB pericarditis is a more aggressive disease with a greater degree of myocardial involvement. Patients have larger pericardial effusions with more frequent hemodynamic compromise and more significant ST segment changes in the electrocardiogram. HIV alters the natural history and outcomes of TB pericarditis. Immunocompromised participants appear less likely to develop constrictive pericarditis and have a significantly higher mortality compared with their immunocompetent counterparts. Finally co-infection with HIV has resulted in a number of areas of uncertainty. The mechanisms of myocardial dysfunction are unclear, new methods of improving the yield of TB culture and establishing a rapid bacterial diagnosis remain a major challenge, the optimal duration of anti-TB therapy has yet to be established, and the role of corticosteroids has yet to be resolved.

Pericardial effusion complicating novel influenza A (H1N1) infection in an infant

We report the case of a 3-month-old boy with novel influenza A (H1N1) infection complicated by pericardial effusion. The patient was treated with pericardial drainage, oseltamivir, and ibuprofen and improved. Pericarditis and pericardial effusion have been occasionally associated with influenza A infections. To our knowledge, this is the first case of pericardial effusion reported during the current novel influenza A (H1N1) pandemic.

Recombinant cardiac myosin fragment induces experimental autoimmune myocarditis via activation of Th1 and Th17 immunity

The specificity and function of T helper (Th) immune responses underlying the induction, progression, and resolution of experimental autoimmune myocarditis (EAM) in A/J mice are unclear. Published data suggest involvement of both Th1 and Th2 responses in EAM; however, the previous inability to assess antigen-specific in vivo and in vitro T-cell responses in cardiac myosin-immunized animals has confounded our understanding of this important model of autoimmune myocarditis. The goal of our study was to develop an alternative model of EAM based on a recombinant fragment of cardiac myosin, in hopes that the recombinant protein will permit measurement of functional T-cell responses that is not possible with purified native protein. A/J mice immunized with a recombinant fragment of cardiac myosin spanning amino acids 1074-1646, termed Myo4, developed severe myocarditis characterized by cardiac hypertrophy, massive mononuclear cell infiltration and fibrosis, three weeks post-immunization. The mice also developed an IgG1 dominant humoral immune response specific for both Myo4 and purified cardiac myosin. The in vitro stimulation of splenocytes harvested from Myo4-immunized animals with Myo4 resulted in cellular proliferation with preferential production of the Th1- and Th17-associated cytokines, IFN-gamma, IL-17, and IL-6, respectively. Production of IL-4 was negligible by comparison. This study describes a new model of EAM, inducible by immunization with a specific fragment of cardiac myosin, from which antigen-specific analyses reveal an importance for both Th1 and Th17 immunity.

A modern approach to tuberculous pericarditis

The human immunodeficiency virus (HIV) epidemic has been associated with an increase in all forms of extrapulmonary tuberculosis including tuberculous pericarditis. Tuberculosis is responsible for approximately 70% of cases of large pericardial effusion and most cases of constrictive pericarditis in developing countries, where most of the world's population live. However, in industrialized countries, tuberculosis accounts for only 4% of cases of pericardial effusion and an even smaller proportion of instances of constrictive pericarditis. Tuberculous pericarditis is a dangerous disease with a mortality of 17% to 40%; constriction occurs in a similar proportion of cases after tuberculous pericardial effusion. Early diagnosis and institution of appropriate therapy are critical to prevent mortality. A definite or proven diagnosis is based on demonstration of tubercle bacilli in pericardial fluid or on histologic section of the pericardium. A probable or presumed diagnosis is based on proof of tuberculosis elsewhere in a patient with otherwise unexplained pericarditis, a lymphocytic pericardial exudate with elevated biomarkers of tuberculous infection, and/or appropriate response to a trial of antituberculosis chemotherapy. Treatment consists of 4-drug therapy (isoniazid, rifampicin, pyrazinamide, and ethambutol) for 2 months followed by 2 drugs (isoniazid and rifampicin) for 4 months regardless of HIV status. It is uncertain whether adjunctive corticosteroids are effective in reducing mortality or pericardial constriction, and their safety in HIV-infected patients has not been established conclusively. Surgical resection of the pericardium is indicated for those with calcific constrictive pericarditis or with persistent signs of constriction after a 6 to 8 week trial of antituberculosis treatment in patients with noncalcific constrictive pericarditis.

Cardiac myosin and autoimmune myocarditis

Infection with type 3 of the group B Coxsackieviruses (CB3) sometimes leads to the development of myocarditis in humans. Circumstantial evidence in the form of heart-reactive antibodies in these cases of human myocarditis suggests that the later phases of the disease may be due to autoimmunization. Since human myocarditis is a relatively rare sequel to infection with CB3 virus, we propose that it reflects a genetic predisposition in some individuals. To investigate this possibility we established an experimental murine model of viral myocarditis. By testing a large number of strains of inbred mice infected with CB3 we found that a few strains developed an ongoing myocarditis characterized by diffuse interstitial mononuclear infiltration and by the production of heart-specific IgG autoantibodies. These antibodies reacted with myocardial sarcolemma and myofibrils as well as with muscle striations. The principal myocardial autoantigen, identified by means of postinfectious sera of mice with heart-specific autoantibodies, was found to be the cardiac isoform of myosin. Immunization of susceptible mice with cardiac myosin stimulated the production of heart-specific antibodies reactive with both cardiac muscle striations and sarcolemma, accompanied by mononuclear infiltration of the myocardium. From these results we infer that cardiac myosin is an autoantigen capable of inducing postinfectious myocarditis in genetically predisposed individuals.

Bacterial pericarditis: diagnosis and management

Bacterial pericarditis occurs by direct infection during trauma, thoracic surgery, or catheter drainage, by spread from an intrathoracic, myocardial, or subdiaphragmatic focus, and by hematogenous dissemination. The frequent causes are Staphylococcus and Streptococcus (rheumatic pancarditis), Haemophilus, and M. tuberculosis. In AIDS pericarditis, the incidence of bacterial infection is much higher than in the general population, with a high proportion of Mycobacterium avium-intracellulare infection. Purulent pericarditis is the most serious manifestation of bacterial pericarditis, characterized by gross pus in the pericardium or microscopically purulent effusion. It is an acute, fulminant illness with fever in virtually all patients. Chest pain is uncommon. Purulent pericarditis is always fatal if untreated. The mortality rate in treated patients is 40%, and death is mostly due to cardiac tamponade, systemic toxicity, cardiac decompensation, and constriction. Tuberculous infection may present as acute pericarditis, cardiac tamponade, silent (often large) relapsing pericardial effusion, effusive-constrictive pericarditis, toxic symptoms with persistent fever, and acute, subacute, or chronic constriction. The mortality in untreated patients approaches 85%. Urgent pericardial drainage, combined with intravenous antibacterial therapy (e.g. vancomycin 1g twice daily, ceftriaxone 1-2g twice daily, and ciprofloxacin 400 mg/day) is mandatory in purulent pericarditis. Irrigation with urokinase or streptokinase, using large catheters, may liquify the purulent exudate, but open surgical drainage is preferable. The initial treatment of tuberculous pericarditis should include isoniazid 300 mg/day, rifampin 600 mg/day, pyrazinamide 15-30 mg/kg/day, and ethambutol 15-25 mg/kg/day. Prednisone 1-2 mg/kg/day is given for 5-7 days and progressively reduced to discontinuation in 6-8 weeks. Drug sensitivity testing is essential. Pericardiectomy is reserved for recurrent effusions or continued elevation of central venous pressure after 4-6 weeks of antituberculous and corticosteroid therapy.

Tuberculous pericarditis

BACKGROUND

The incidence of tuberculous pericarditis is increasing in Africa as a result of the human immunodeficiency virus (HIV) epidemic. The primary objective of this article was to review and summarize the literature on the pathogenesis, diagnosis, and management of tuberculous pericarditis.

METHODS AND RESULTS

We searched MEDLINE (January 1966 to May 2005) and the Cochrane Library (Issue 1, 2005) for information on relevant references. A "definite" diagnosis of tuberculous pericarditis is based on the demonstration of tubercle bacilli in pericardial fluid or on a histological section of the pericardium; "probable" tuberculous pericarditis is based on the proof of tuberculosis elsewhere in a patient with otherwise unexplained pericarditis, a lymphocytic pericardial exudate with elevated adenosine deaminase levels, and/or appropriate response to a trial of antituberculosis chemotherapy. Treatment consists of the standard 4-drug antituberculosis regimen for 6 months. It is uncertain whether adjunctive corticosteroids are effective in reducing mortality or progression to constriction. Surgical resection of the pericardium remains the appropriate treatment for constrictive pericarditis. The timing of surgical intervention is controversial, but many experts recommend a trial of medical therapy for noncalcific pericardial constriction, and pericardiectomy in nonresponders after 4 to 8 weeks of antituberculosis chemotherapy.

CONCLUSIONS

Research is needed to improve the diagnosis, assess the effectiveness of adjunctive steroids, and determine the impact of HIV infection on the outcome of tuberculous pericarditis.

Subacute tuberculous pericarditis with fibroelastic constriction diagnosed upon pericardiectomy

A patient with subacute pericarditis showed no evidence suggesting tuberculosis until pericardiectomy was performed because of hemodynamic deterioration. The excised pericardium had a rubbery fibroelastic consistency; histologically, there were granulomatous changes characteristic of tuberculosis. Although tuberculous pericarditis is a difficult diagnosis, this case illustrates the diagnostic and therapeutic importance of early pericardiectomy before myocardial inflammatory infiltration occurs together with end-stage pericardial fibrosis and calcification.

Intrapericardial treatment of inflammatory and neoplastic pericarditis guided by pericardioscopy and epicardial biopsy--results from a pilot study

From a registry of 136 patients undergoing pericardiocentesis, 14 patients with autoimmune and 15 patients with neoplastic effusions were selected. All underwent pericardioscopy, epicardial and pericardial biopsy with histologic, immunohistologic, and polymerase chain reaction/or in situ hybridization analysis for microbial DNAs and RNA. Pericardioscopy identified neoplastic effusions by the high occurrence of protrusions. Fibrin threads and layers and neovascularization were found in both groups. For identification of the inflammatory and neoplastic process, the combined analysis of the cytology of the effusion and epicardial biopsy evaluation proved to be most important. Epicardial biopsy demonstrated a slightly higher sensitivity for identifying neoplastic disorders in the pericardium than cytology alone. Pericardial biopsy was inconclusive. Intrapericardial administration of 1 g of crystalloid triamcinolone in autoreactive pericarditis prevented recurrence in 13 of the 14 cases after 3 months and in 12 of the 14 cases after 1 year. In neoplastic effusion, intrapericardial administration of 50 mg cis-platin for 24 h prevented recurrence of a hemodynamically relevant effusion after 3 months in all, and after 6-12 months in 14 of 15 patients. Mortality in neoplastic effusion due to noncardiac tumor progression was 47 and 80%, respectively, after 3 and 6 months, as can be expected in endstage neoplastic disease. This pilot study demonstrates that local drug application is feasible, life-saving, and well tolerated by the patients. It opens perspectives for local drug application in other cardiac disorders as well.

Circulating heart-reactive antibodies in patients with myocarditis or cardiomyopathy

Heart-reactive antibodies are commonly observed in patients with myocarditis or cardiomyopathy. Such antibodies may be important in the pathogenesis of these disorders, yet the specific antigens recognized have not been studied systematically. This report characterizes circulating heart autoantibodies from patients with myocarditis (n = 17) or idiopathic cardiomyopathy (n = 71) and from healthy volunteers (n = 15). Indirect immunofluorescence demonstrated that high titer (greater than or equal to 1:20) immunoglobulin G (IgG) antibody activity occurred in 59% of the myocarditis samples, 20% of the cardiomyopathy samples and none of the normal samples. All samples were tested by Western immunoblotting for IgG activity against a normal human heart extract. The number of antigens recognized by each sample was enumerated and the molecular weight of each antigen estimated; the prevalence of reactivity against antigens in selected molecular weight classes was determined. There was no difference in the mean number of heart antigens recognized by serum from each group. For most weight classes, prevalence either did not differ significantly among the various groups or subgroups or was greatest among samples from healthy volunteers. Prevalence of reactivity with 190 to 199 kilodalton (kd) antigens was greatest (p less than 0.05) among low titer serum samples from patients with myocarditis. High titer cardiomyopathy serum differed from normal serum by an increased (p less than 0.05) prevalence of antibodies to 40 to 49 and 100 to 109 kd antigens. These results suggest that western immunostaining may ultimately contribute substantively to identifying patients with myocarditis or cardiomyopathy.

Novel organ-specific circulating cardiac autoantibodies in dilated cardiomyopathy

To determine whether organ-specific cardiac autoantibodies are present in dilated cardiomyopathy, indirect immunofluorescence on human heart and skeletal muscle was used to test sera from 200 normal subjects and from 65 patients with dilated cardiomyopathy, 41 with chronic heart failure due to myocardial infarction and 208 with other cardiac disease. Three immunofluorescence patterns were observed: diffuse cytoplasmic on cardiac tissue only (organ-specific), fine striational on cardiac and, to a lesser extent, skeletal muscle (cross-reactive 1) and broad striational on both cardiac and skeletal muscle (cross-reactive 2). Cardiac specificity of the cytoplasmic pattern was confirmed by absorption studies with homogenates of human atrium, skeletal muscle and rat liver. Organ-specific cardiac antibodies (IgG; titer range 1/10 to 1/80) were more frequent in patients with dilated cardiomyopathy (17 [26%] of 65) than in those with other cardiac disease (2 [1%] of 208, p less than 0.0001) or heart failure (0 [0%] of 41, p less than 0.001) or in normal subjects (7 [3.5%] of 200, p less than 0.0001). Organ-specific cardiac antibodies were more common in patients with dilated cardiomyopathy and in those with fewer symptoms (8 of 15 in New York Heart Association functional class I versus 9 of 50 in classes II to IV, p less than 0.01) and more recent (less than 2 years) onset of disease (9 of 19 versus 8 of 46, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Desmin antibodies in acute infectious myopericarditis

The role of autoantibodies against cardiac tissue in the pathogenesis of acute myopericarditis is poorly understood--partly because the specificity of the antibodies is unknown. We assayed antibodies against desmin, a cytoskeletal muscle protein, in 18 patients with acute infectious myopericarditis (AIM), in 24 patients with acute uncomplicated infections, in ten patients with acute myocardial infarction, and in 68 blood donors by an immunoenzymatic assay using purified desmin from Purkinje fibers of cow heart. In addition, anti-heart antibodies were assayed by indirect immunofluorescence. Anti-heart antibodies were detected in all groups by indirect immunofluorescence. On the other hand, anti-desmin antibody levels exceeding the mean + 2 SD of the blood donors could demonstrated in seven (39%) AIM patients but in only one patient in the other groups. The analysis of serial samples indicated that the antibody level was highest in the acute phase of AIM and declined during the recovery.

Antibodies to human sinus node in sick sinus syndrome

The incidence of autoantibodies against human conducting tissue was studied in 45 pacemaker patients with sick sinus syndrome (SSS), in 17 patients with bradyarrhythmia, and five patients with hypersensitive carotid sinus syndrome. Antibodies against the human sinus node were demonstrated in 29% of patients with SSS and in 24% of patients with bradyarrhythmia; a tenfold risk of SSS could be calculated in patients with this antibody as compared to age-matched controls. At least two subtypes of anti-sinus node antibodies were demonstrated: an antibody absorbable and another one not absorbable with ventricular myocardium. Patients with SSS and prior myocarditis of rheumatic fever have a threefold incidence of that antibody, demonstrating that anti-conducting tissue antibodies are etiologic indicators for former inflammatory heart disease. These antibodies may play a role in the secondary immunopathogenesis of sick sinus syndrome. This hypothesis emerges as an interesting new pathogenetic concept.

Rickettsial perimyocarditis--a follow-up study

Sera and lymphocytes from a 37-year-old male patient with acute perimyocarditis during a Q-fever endemic were analyzed for antibody and cell-mediated immune reactions and followed up 28 months later. Circulating autoantibodies against myocardial tissue were assessed by indirect immunofluorescence. Cytolysis of vital contracting rat cardiocytes, by antimyolemmal antibodies and complement, and lymphocytotoxicity, with and without the patient's serum, were evaluated and compared with the results obtained in ten patients suffering from Q-fever without perimyocardial involvement and with 40 healthy subjects. Antimyolemmal antibodies (AMLA), a muscle-specific subtype of antisarcolemmal antibodies, were demonstrated by immunofluorescence in the one patient with Q-fever perimyocarditis in titers of up to 1:320 but not in the controls. AMLA induced cytolysis of myocytes in the presence of complement. Both AMLA and cytolytic serum activity could be absorbed in all sera of this patient by using Coxiella burnetii. Only marginal lymphocytotoxicity against heterologous cardiocytes was detected in the early phase and again during the follow-up 2 years later in the Q-fever myocarditis patient but not in any of the noncarditic Q-fever cases nor in controls. It is postulated that cross-reacting, complement-fixing, cytolytic autoantibodies against the cardiac myolemma are operative either as a cause of cardiac damage or a consequence, pointing to a secondary immunopathogenesis of chronic Q-fever perimyocarditis.

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.

Post-cardiac injury syndrome and an increased humoral immune response against the major contractile proteins (actin and myosin)

To better understand the pathogenesis of the post-cardiac injury syndrome (PCIS) 2 models of cardiac injury were studied. One hundred twenty-nine patients who underwent cardiac surgery and 80 patients with acute myocardial infarction (AMI) were prospectively followed and the levels of anti-heart antibodies (AHA), anti-actin antibodies (AAA) and anti-myosin antibodies (AMA) were determined. In the surgical group, PCIS developed in 27 patients (21%) and incomplete PCIS in 36 (28%). In the AMI group, PCIS did not develop in any patient, but incomplete PCIS developed in 11 patients (14%) (p less than 0.001). The surgical group showed a significantly higher humoral immune response than the AMI group when analyzed for AHA and anti-contractile protein antibodies. After cardiac surgery, AHA developed in 59 patients (46%), AAA developed in 33 (26%) and AMA developed in 49 (38%); in the AMI group, significant levels of AHA, AAA and AMA developed in 16 (20%), 7 (9%) and 13 patients (16%), respectively. These studies show a significant correlation between the PCIS clinical classification and auto-antibodies raised against heart contractile proteins.

Immunologic regulator and effector mechanisms in myocarditis and perimyocarditis

The diagnosis and etiology of myocarditis and perimyocarditis are often difficult to ascertain. We therefore investigated regulator and humoral and cellular effector mechanisms in patients with viral heart disease (Coxsackie B3, influenza, EBV, mumps). In acute carditis, OKIA1-positive cells were increased and no significant alteration in suppressor cell activity was observed in our patients in contrast to others reports. The characteristic immunofluorescent pattern is the presence of antimyolemmal antibodies (AMLA) with rat and human collagenase-pretreated intact cardiocytes (in titers of 1:40-1:320) as antigens. The pattern is indistinguishable on cardiocytes from antibodies against cytoskeletal antigens (microtubules, intermediate filaments--tubulin/vemitin) when associated with antibodies directed against the Z-bands. In contrast, only anti-interfibrillary antibodies are present in cytomegalovirus myocarditis. The antimyolemmal fluorescence can be absorbed with the respective causative virus, indicating that the antibodies are cross-reactive. AMLA-positive sera induce cytolysis of vital rat cardiocytes in vitro, indicating 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-type antibodies to the sarcolemma that also fix complement. In the acute phase of carditis, circulating immune complexes were also measured, thus monitoring immunoreactivity. Cellular effector mechanisms against vital cardiocytes were maintained or even slightly enhanced; in vitro NK-cell activity against K 562, however, was decreased. This is compatible with a more target-specific cytotoxicity in carditis but reduced NK-cell activity in peripheral blood cells.

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.

Quantification of antimyosin antibodies in experimental myocarditis by a new solid phase fluorometric assay

A solid phase fluorometric assay of high sensitivity and specificity for detection of antimyosin antibodies is described. The method consists of 4 basic steps: (1) coating the carrier stiQ with myosin; (2) incubation of the stiQ in the test serum; (3) labeling of the bound antibodies by FITC-anti-immunoglobulin antibodies; and, (4) quantitation of the bound antibodies in a fluorometer (FIAXTM). Using a purified myosin preparation as antigen, the assay was tested in experimental myocarditis of rabbits injected with cardiac proteins. Reproducibility was excellent, standard deviation of intra-assay variance being 7.86%, and inter-assay variance 9.45%. When compared with immunodiffusion, a complement fixation test with myosin and indirect immunofluorescence, the assay described proved superior since it allows simple monitoring of serum concentrations of antimyosin antibodies.

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.