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Extracellular antigens have been isolated from Streptococcus mitis, Streptococcus salivarius and group A streptococcal cultures grown in a synthetic medium. Analysis of the antigens was performed by immunoelectrophoretic and double diffusion techniques using rabbit immune sera. S. mitis cultures produced 10 antigens, S. salivarius six antigens and group A streptococcus 12 antigens, when tested with their corresponding antisera. S. mitis and S. salivarius antigens had only one common antigen when tested with antisera to both antigen pools. No cross reaction was found between the exo-antigens of group A and viridans streptococci. While the extracellular antigen pool of group A streptococci contained ribonuclease, deoxyribonuclease, hyaluronidase, diphosphopyridine-nucleotidase, streptokinase and streptolysin 0, that of S. mitis contained only ribonuclease and that of S. salivarius contained hyaluronidase and collagenase. Each of the three streptococcal antigen pools contained a hemosensitizing factor which sensitized mammalian cells to passive immune kill. Sonicates produced from the mitis, salivarius and group A streptococcus contained six antigens, most of which cross reacted with each other. S. mitis sonicates were separated into six fractions by ion exchange chromatography on ECTEOLA cellulose, and into three major fractions following gel-filtration on Sephadex 0-200 columns. Rabbits injected i.v. with sonicates derived from S. mitis developed cardiac and hepatic lesions which, in some cases, were accompanied by a steep rise in serum glutamic oxalacetic transaminase, sorbitol dehydrogenase and total lipids. The relationship of tissue damage to enzyme rise is discussed in relation to the possible early diagnosis of tissue damage following streptococcal infection.

Rabbits injected with streptococcal extracellular protein (SEP) developed degenerative and infiltrative lesions in the heart and liver, with coagulation necrosis and multinucleated giant cells in the latter organ. The majority of these rabbits also showed elevated levels of glutamic-oxalacetic transaminase, or of sorbitol dehydrogenase, and all showed elevated serum lipids. These biochemical indications of cell injury could be found within 2 to 4 hours after a first injection of SEP. No such biochemical or pathologic effects were found following an injection of heated SEP or a commercially available streptokinase-streptodornase preparation from group C streptococcal culture. In a preliminary fractionation of SEP all the activity was found in a fraction not adsorbed to DEAE cellulose at pH 7.4 (0.05 M P04). The active fraction contained at least five antigens and four of the known streptococcal enzymes. Injection of extracts of sonically disrupted streptococci produced similar biochemical and pathologic changes. There was some cross-reacting material between the sonicates and anti-SEP serum.

Various streptococcal species produce an haemosensitizing factor during the logarithmic phase of growth. A variety of mammalian cells sensitized with this factor become agglutinated following the addition of antistreptoccocal serum and also undergo cytopathic changes in the presence of complement. The haemosensitizing factor is thermostable and is unaltered by trypsin, papain, chymotrypsin, lipases or ribonucleases. Attempts to destroy the binding sites on the cell membrane by treatment with phospholipase C from Clostridium welchii or by neuraminidase failed. Treatment with trypsin or papain on the other hand markedly increased the binding capacity of red blood cell for the haemosensitizing factor. Studies on the nature of the binding sites on the erythrocyte membrane of the haemosensitizing factor suggest that cholesterol and phospholipids constitute some of the binding sites for this factor.

Many studies have been made of tissue alterations due to infections with Group A streptococci in laboratory animals. Cardiac lesions characterized by muscle necrosis, myocarditis, and giant-cell formation have been reported in a variety of laboratory animals following injections of living Group A streptococci and some of their products.1l Some of these lesions were described as quite similar to the Aschoff bodies of rheumatic carditis.4 The mechanism of formation of these cardiac lesions has been attributed to toxic effects of streptococcal products,6 7 to immune response to streptococcal components (hypersensitivity or autoimmunity) ,10 or to combinations of these processes. Among these studies, the pharyngeal cavity of animals was used as the portal of entry of streptococci only in that of Glaser et al.,11 who found cardiac lesions within 72 hr. of a single intratonsillar injection of virulent Group A streptococci. These lesions were focal, and showed muscle necrosis, infiltrations of mononuclear cells, and occasional giant cells. No streptococci could be isolated from such lesions, and it was concluded that the lesions were probably not caused by an immunologic process."' The present report describes the induction of lesions in cardiac and other tissues of rabbits following injection, by intratonsillar and other routes, of streptococcal extracellular products (SEP) obtained from Group A streptococci grown in steady-state culture. These lesions occured soon after single injections of these materials and probably reflect direct toxic effect on the cells of these tissues.