Autoreactive mechanisms in infective endocarditis

Abstract

Summary.Infective endocarditis is not a simple interaction between a microbial agent and a cardiac valve. For the infection of a non-bacterial thrombotic vegetation, predisposition is required which is at least partially operative by a decreased suppressor T cell activity. During infection, peripheral blood natural killer cell activity is decreased, but normalizes under anti-microbial therapy. Non-major histocompatibility complex-restricted lymphocytotoxicity to isolated heart cells can be present in one third of patients. Circulating immune complexes normalize during therapy. They may be the cause of many clinical symptoms of infective endocarditis. Anti-bacterial and also anti-sarcolemmal antibodies which are crossreactive to the bacterium are secreted in a polyclonal immune response. Anti-sarcolemmal antibodies which are cytolytic in vitro in the presence of complement may partly explain the myocardial factor of heart failure in patients with only marginal valve incompetence due to the endocarditic vegetation.

Immune responses in endocarditis

“…Maisch found that the polyclonal antibody response in endocarditis included antimyolemmal and antisarcolemmal antibodies 7. The antisarcolemmal antibodies could be shown to cross react with streptococcal antigens, as demonstrated previously in rheumatic fever and for viral antigen in myocarditis.…”

Natural Autoantibodies: An Undersugn Hero of the Immune System and Autoimmune Disorders—A Point of View

“…It is well known that in sympathetic ophthalmia, release of hidden autoantigens in abundance, from, e.g., trauma of one eye are readily recognized by circulating preexisting autoreactive lymphocytic clones leading to autoimmune insult in the other eye ( 27 ). It is also well understood that chronic activation of the immune system, as occurs in chronic infections like subacute bacterial endocarditis ( 28 ), leishmaniosis ( 29 ), and others, may lead, in genetically susceptible individuals, to immune complex formation and development of autoimmune disease. Furthermore, many years ago, we have shown, followed by others that chronic activation of the immune system, as occurs in individuals who received allogeneic bone transplants and develop chronic graft versus host disease also leads to the development of a variety of systemic autoimmune diseases such as systemic lupus erythematosus (SLE), Sjögren’s syndrome, biliary cirrhosis, and scleroderma ( 30 – 32 ).…”

Dealing with the Substance Abuse Epidemic and Infective Endocarditis:Clinical, Immunologic and Pathogenetic Aspects

“…There are several reports of autoreactive mechanisms in IE, including polyclonal antibody response. Maisch [76] have reported the presence of antimyolemmal and antisarcolemmal antibodies. The former were cytolytic in vitro to heart cells in the occurrence of complement and the later were cross-reacting with streptococcal antigens.…”