Self-perpetuating arthritis was induced in knee joints of rabbits by intraarticular injections of large amounts of cell free extract derived from group A streptococci disintegrated mechanically. The pathological alterations were characterized by synovial lining cell proliferation, polymorphonuclear and mononuclear cell infiltration with the appearance of pseudo-follicles and pannus formation. Electron microscopical proliferation of B cells was predominant. An active inflammatory exudate and numerous new capillaries were also seen. The induced arthritis was self-perpetuating and appears to resemble human rheumatoid arthritis.

In previous reports (1, 2) it has been shown that lysosomal enzymes derived from various populations of mammalian leukocytes failed to degrade 14C-Iabeled group A streptococci in vitro, On the other hand, Staphylococcus albus, Micrococcus Iysodeikticus and Escherichia coli were degraded to a large extent by leukocyte lysosomal enzymes. It was thus of interest to study the degradation of a variety of labeled microorganisms in vivo in inflammatory lesions in the thigh muscle of the mouse induced by the injection of heat-killed microorganisms. The results indicate that there may be a correlation between the degree of degradation of microorganisms by leukocyte lysates in vitro (1, 2) and the length of their persistence in lesion sites in vivo.

In previous reports (1-3), it has been shown that lysosomal enzymes derived from a variety of mammalian leukocyte populations degrade 14C-Iabeled Micrococcus lysodeikticus and Staphylococcus albus extensively. On the other hand, group A streptococci are very resistant to lysis by leukocyte lysates. It has also been shown that, unlike S. albus and M. lysodeikticus, streptococci which are resistant to lysis in vitro persist for long periods in granulomatous lesions in mouse and rabbit tissues (1, 2). Other reports (4, 5) have shown that bacteria coated with specific antibodies are degraded at a slower rate following phagocytosis, as compared with untreated bacteria. Cationic polyelectrolytes, such as polylysine and polyarginine, agglutinate a variety of bacteria (6), and cationic proteins derived from leukocytes as well as from calf thymus histone are bactericidal for a variety of microorganisms (7). The possibility was therefore investigated that, by analogy to antibodies, cationic proteins may coat bacterial cells and thus interfere with their degradation by leukocyte lysosomal enzymes.

The evaluation of the streptozyme test in sera from 34 patients with streptococcal pyodermal nephritis was studied. Ninety-seven percent of the patients developed high titers of antistreptozyme antibodies on the first bleeding after hospitalization, in contrast to only 40% of patients who developed elevated antistreptolysin O titers. The high antistreptozyme titers declined during convalescence and reached normal levels in the sixth month after onset of the disease. The most significant fall in titers occurred between 1 and 2 months from the onset of disease. The streptozyme test may be particularly helpful as a rapid screening test for antibodies in streptococcal pyodermal nephritis.

Earlier reports had described the presence, in supernates of streptococcal steady-state cultures, of a macromolecular toxin which causes infiltrative and necrotic lesions in the heart and liver of rabbits and changes in the serum level of certain enzymes and lipids. In the present study, following treatment of the culture supernate concentrates with trichloroacetic acid and ethanol, and dialysis, material with these biologic activities has been found, in the dialysate, and was not excluded by Sephadex G-15. The molecular weight of the toxin, by this criterion, is near that of vitamin B12.

Although numerous epidemiological and clinical studies have shown a definite relationship between a previous infection with strains of Group A streptococci and the appearance of sequelae (rheumatic fever, arthritis, nephritis), the mechanisms which lead to their development are still not fully understood. Since man is the only animal species which suffers from natural infections with Group A streptococci, and since it is agreed that viable streptococci cannot usually be isolated from the lesions characteristic of the chronic complications, Koch’s postulate can at best incriminate these micro-organisms only in the etiology of the acute infections but not in their subsequent complications. Despite many attempts to duplicate rheumatic fever, arthritis and acute glomerulonephritis in laboratory animals including higher apes, as a rule, the tissue lesions which developed in some of the animals bore little resemblance to the human lesions, and no true duplication of a disease syndrome similar to that seen in human beings has been reported. Two major theories have been proposed by various investigators to explain the nature of poststreptococcal complications. One theory proposes that the toxic effects of some streptococcal products (streptolysins O and S, erythrogenic toxin, proteinase, cell-wall mucopeptide-polysaccharide complex) are responsible for the initiation of the chronic lesions in the heart, joint and kidney characteristic of poststreptococcal diseases. The second theory suggests that the immunopathological phenomena (immune complex disease, cross-reactive immunity, delayed hypersensitivity) which develop in certain pa- tients who have become sensitized to one or more of the streptococcal products are responsible for the initiation of the disease in man. These two hypotheses are not, of course, mutually exclusive. Although no unified theory has been advanced which adequately explains the nature of the various post- streptococcal complications, a combination of both views may fit many, if not all, the features characteristic of these sequelae. Some theories on the pathogenesis of human poststreptococcal diseases and on the mechanisms of tissue injury induced by Group A streptococci have been recently reviewed (Taranta and Uhr, 1971; Ginsburg, 19720, b). The purpose of this paper is to describe some of the mechanisms by which Group A streptococci localize and persist in mammalian tissues and to relate the experimental models to the pathogenesis of poststreptococcal sequelae in man.

Streptolysin S exists in a cell-bound form and as an extracellular complex between a nonspecific carrier (serum, serum albumin, ribonucleic acid [RNA], Triton, Tween) and a hemolytic moiety (probably a peptide) synthesized by streptococci. Although all the forms of streptolysin S, at 100 hemolytic units, killed mouse leukocyte monolayers, the time needed to kill 100% of the cells varied with the different streptolysin S preparations. Whereas 30 min was sufficient for the cell-bound hemolysin to kill all of the cells, 60 and 180 min were required when RNA streptolysin S and serum streptolysin S, respectively, were employed. Addition of 10% mouse serum to RNA streptolysin S or to cell-bound hemolysin delayed the killing of the leukocytes. The delayed killing observed with serum and albumin hemolysins is probably due to competition for the hemolytic moiety between the carrier molecules and target sites (phospholipids) upon the leukocyte membrane. Serum streptolysin S must be constantly incubated with the cells for 90 min for 100% of the cells to undergo cytopathic changes upon subsequent incubation for an additional 90 min. Streptolysin S inhibitor (trypan blue) added to the system after 30 or 60 min of incubation resulted in the killing of 50 and 100% of the leukocytes, respectively, when the cells were further incubated for 120 min. It is suggested that 30 min of incubation was not sufficient for the transfer of enough streptolysin S molecules upon the cell surface to allow killing of all of the cells. Sublethal amounts of streptolysin S, streptolysin O, and saponin suppressed phagocytosis of streptococci by mouse peritoneal macrophages. This effect was abolished by inhibitors of streptolysin S (trypan blue) and of streptolysin O and saponin (cholesterol). With sublethal amounts of streptolysin S, no inhibition of the reduction of nitro blue tetrazolium by nonphagocytosing cells was observed, but these amounts of streptolysin S caused a 50% inhibition of the reduction of nitro blue tetrazolium by phagocytosing leukocytes. It is suggested that some metabolic systems, which are normally enhanced during phagocytosis, have been affected by sublethal doses of streptolysin S. The results indicate that the in vivo production of small amounts of streptolysins S and O by group A streptococci may inhibit phagocytosis and may thus contribute to the invasiveness and pathogenicity of this microorganism.

The cell-sensitizing factor (SF) of group A streptococci is a teichoic acid which can sensitize mammalian cells to agglutination and lysis in the presence of anti ·SF antibodies and complement. SF is highly immunogenic in the rabbit when bound naturally to some constituent of the streptococcus cell, but only feebly so when it is extracted from the cells by phenol. Both rabbit and human antibodies to SF, which are mainly associated with the macroglobulin fraction (IgM) of serum, are destroyed by treatment with 2-mercaptoethanol. While human anti-SF antibodies are readily destroyed by freezing and thawing and by heating to 58 C, the rabbit anti-SF antibodies are not destroyed at 64 C and are relatively resistant to repeated freezing and thawing. Complexes formed between SF and rabbit antibodies fix complement both in the absence and presence of red blood cells (RBC). Anti-SF antibodies interact with SF and prevent the latter from sensitizing RBC. Rabbits immunized with heat-killed streptococci and which developed anti-SF antibodies, developed severe arthritis when SF was injected into their knee joints. The arthritic lesions were characterized by a marked proliferation of the synovial membrane, a chronic inflammatory exudate and the accumulation of large numbers of lymphocytes in the form of "pseudolymphatic follicles." Nonimmunized animals failed to develop such lesions. It is suggested that sensitization of cells with SF during streptococcal infection may lead to passive immune cytolysis and may thus contribute to the pathogenicity of streptococci.

The production of extracellular nicotinamide adenine dinucleotide glycohydrolase (NADG) and the cell-bound lipoproteinase (serum opacity reaction, SOR) by strains of different serological types of group A streptococci, in relation to the T typing, was studied. The production of both NADG and SOR, or only one of them, was found to be characteristic of serotypes, as determined by M and T antigen. No difference in the production of these enzymes was found in relation to M-positive and M-negative variants. Investigation into NADG and SOR production as related to the T type enabled the division of a single agglutination pattern into four main groups, each of which corresponds to one specific M type or more. Of the 370 strains belonging to 12 different T-agglutination patterns, 21% produced both enzymes and 42.5% failed to produce any of them, whereas the remaining 36.5% produced only one out of the two enzymes. Five streptococcal types which did not produce NADG and SOR also failed to synthesize streptolysin S at the early logarithmic phase of growth, indicating that streptolysin S production by young cultures may be also related to serotype. No correlation was found between the production of NADG-SOR as related to serotype and the production of streptolysin O, acid phosphotase, esterase, N-acetylglucosaminidase, hyaluronidase, streptokinase, and the cell-sensitizing factor. The practical and potential usefulness of NADG and SOR production in epidemiological studies is discussed.

Washed suspensions of group A, C, and G streptococci and group A L-forms possess phosphatase, esterase, and N-acetylglucosaminidase, respectively. Cell-free extracts, obtained from streptococci and Informs by mechanical disintegration or by treatment of group A streptococci with phage-associated lysin, possess, in addition to these enzymes, an adenosine triphosphatase (ATPase). Over 90% of the total ATPase and NAGAase and 50% of phosphatase and esterase activities were solubilized by cell breakage, indicating that the latter 2 enzymes are membrane-bound. A partial separation between the phosphatase, NAGAase, and ATPase was achieved by gel filtration of cell-free extracts on Sephadex G-200. Phosphatase was eluted with high molecular weight material excluded from the column. NAGAase and ATPase were associated with much lower molecular weight fractions, while esterase activity was present in both high and low molecular weight fractions. Studies on substrate specificity showed that fractions which split PNP-phosphate also split PNP-acetate and PNP-propionate fractions which split ATPase also split CTP, ITP, and GTP but to a lesser extent. Fractions which were active against β-napthylacetate also split β-naphthyl butyrate (15% efficiency); no activity against longer fatty acid esters of PNP or β-naphthyl derivatives was present.

Rabbits injected intravenously with extracellular products ("toxins") of group A streptococci develop myocardial, muscular, and hepatic lesions. When such animals are then challenged with fluorochrome-labeled group A streptococci or with titanium oxide particles the labeled bacteria or particles localize within phagocytic cells in the tissue lesions caused by the toxins. Similarly, labeled streptococci or titanium oxide particles will also localize within phagocytic cells in skin lesions of guinea pigs that develop delayed hypersensitivity to tuberculin or to bovine gamma globulin. It is proposed that a combined mechanism of injury and localization of bacteria in damaged tissues may be responsible for poststreptococcal sequelae or other chronic inflammatory diseases.

Studies on the host parasite relationship in experimental streptococcal infections have been greatly aided by fluorescent antibody techniques (1). By such methods it is possible to follow the localization and persistence of group A streptococcal antigen in cells and tissues of laboratory animals (2-6). To detect such antigens by fluorescent techniques, frozen sections are often employed and the antisera to streptococcal antigens must be repeatedly absorbed with organ powders to remove nonspecific staining. The present communication describes a simple method for applying a label of fluorescein isothiocyanate (FITC) to living group A streptococci, streptococcal cell-wall fragments,mucopeptides, and streptococcal Lforms. Such labeled streptococci and products were found to persist for long periods of time in inflammatory sites in the muscle and heart of mice and rabbits.