Nonspecific and specific immunological mitogenicity by group A streptococcal pyrogenic exotoxins

Biological effects of Pseudomonas aeruginosa exotoxin A: lymphoproliferation of T lymphocytes in athymic mice

Pseudomonas aeruginosa exotoxin A has been observed to exert modulatory effects on the immune response. The present study examines the ability of exotoxin A to induce proliferation of splenocytes from athymic nu/nu mice. We observed that exotoxin A induced the proliferation of athymic nude splenocytes which could be abrogated by heating the toxin at 70 degrees C or by preincubation of the toxin with rabbit anti-exotoxin A antiserum. Photoaffinity-labelled toxin significantly induced splenocyte proliferation although the relative activity was reduced. Maximum nude splenocyte proliferation was observed at a toxin dose of 100 ng. This same dose was shown previously for athymic splenocytes to induce an enhanced response to the thymus-dependent (TD) antigen, sheep red blood cells (SRBC). The increased [3H]-TdR uptake in athymic splenocytes stimulated by exotoxin A was initiated by 24 hours and continued to day 10. Nude splenocytes depleted of Ig+ and Ia+ cells were induced to proliferate by exotoxin A. Cyclosporin A addition abrogated the ability of exotoxin A to induce proliferation. These results suggest that Pseudomonas aeruginosa exotoxin A can stimulate the proliferation of splenic T lymphocytes in athymic nu/nu mice.

Cross-neutralization of staphylococcal and streptococcal pyrogenic toxins by monoclonal and polyclonal antibodies

We evaluated cross-reactivity of antibodies against staphylococcal and streptococcal pyrogenic toxins. Monoclonal antibodies against staphylococcal enterotoxin (ET) C1 and streptococcal pyrogenic exotoxin (SPE) A were tested for reactivity with homologous and heterologous pyrogenic toxins in vitro. Ten immunoglobulin G1 anti-ET C1 monoclonal antibodies showed little or no cross-reactivity in an enzyme-linked immunosorbent assay, but many of these could neutralize the mitogenic effect of ET B, SPE A, or both. Two immunoglobulin M anti-ET C1 monoclonal antibodies and eight immunoglobulin M anti-SPE A monoclonal antibodies showed extensive cross-reactivity in the enzyme-linked immunosorbent assay and the mitogenicity neutralization assay. No cross-reactivity was observed with SPE C or toxic shock syndrome toxin 1. Rabbits immunized against ET B, ET C1, or SPE A were resistant to challenge with the immunizing toxin. In addition, reciprocal immunity was stimulated by the two ETs, and immunity to SPE A provided protection against ET B but not ET C1. These results show that staphylococcal and streptococcal pyrogenic toxins which share sequence homology have common antigenic determinants which may not be detected in Ouchterlony immunodiffusion assays.

Physiology of the potentiation of lethal endotoxin shock by streptococcal pyrogenic exotoxin in rabbits

Streptococcal pyrogenic exotoxin (SPE) dramatically potentiates the lethal shock induced by gram-negative bacterial endotoxin. To provide further understanding of the mechanism underlying the potentiating effect, the physiological basis for the toxic synergism of the two toxins was investigated. Pretreatment of rabbits with an intravenous (i.v.) dose (10 micrograms/kg of body weight) of SPE greatly enhanced the endotoxin lethality and reduced the 50% lethal dose to less than 5 micrograms of endotoxin per kg. The SPE pretreatment dose caused severe pathophysiological changes in combination with a small i.v. dose of endotoxin (1 microgram/kg). These changes included transient hyperglycemia followed by profound hypoglycemia, elevation of the blood lipoperoxide level, and an acute increase in plasma beta-glucuronidase activity. These changes were comparable with those in animals given a large i.v. dose of endotoxin (100 micrograms/kg) alone. An injection of SPE alone did not alter any of the parameters described above. These results suggest that SPE renders rabbits more sensitive to extensive pathophysiologic effects of endotoxin, and the potentiating effect on endotoxin lethality may thus involve a general potentiation of physiologic failures. The SPE pretreatment depressed the vascular clearance of a large dose of endotoxin (100 micrograms/kg) but failed to affect that of a small dose of endotoxin (1 microgram/kg). The data suggest that the potentiating effect is not readily explained solely on the basis of the decreased clearance of endotoxin.

Investigations on the binding of erythrogenic toxin A of Streptococcus pyogenes on human peripheral blood lymphocytes. I. Light and electron microscopical demonstration of cell surface receptors using colloidal gold-labelled toxin

Receptors for erythrogenic toxin A (ETA) of Streptococcus pyogenes (strain NY-5) were demonstrated on human peripheral blood lymphocytes by binding of ETA-gold conjugates to the cell surface. The specificity of the binding was proved in control experiments. The dark-red granules observed by light microscopy on unfixed cells were revealed by transmission electron microscopy to be patches of gold particles. By light microscopy on samples from 48 blood donors a mean value of 34 +/- 13% of ETA-receptor bearing lymphocytes was ascertained. The predominant part of the cells exhibited only a weak or moderate labelling. Transmission electron microscopy of prefixed cells revealed an attachment of single gold particles distributed over the whole cell surface. Counts of gold particles on serial sections yielded depending on prefixation values of 50-600 receptors/cell (1% glutaraldehyde) and 1000-7000 receptors/cell (0.26% glutaraldehyde), respectively. ETA cloned in Streptococcus sanguis as well as the toxoid of ETA exhibited a comparable binding as ETA (NY-5).

Purification and characterization of Streptococcus pyogenes erythrogenic toxin type A produced by a cloned gene in Streptococcus sanguis

The gene of Streptococcus pyogenes erythrogenic toxin type A (speA) has been previously cloned in Streptococcus sanguis (Challis) and produces extracellular erythrogenic toxin type A (ET A). The ET A produced and secreted by this heterologous host was purified to homogeneity and shown to have properties identical to ET A produced by S. pyogenes strain NY-5; i.e., serological identity in immunodiffusion, migration in SDS-polyacrylamide gel electrophoresis, mitogenic activity, inhibition of mitogenic activity by specific antibody, and precipitation by an international scarlatina antitoxin preparation. The cloned speA gene specified an ET A which had a molecular weight identical to that of ET A from S. pyogenes previously reported from this laboratory. NH2-terminal sequence determination of the purified protein showed the first nine residues to be gln gln asp pro asp pro ser gln leu; this is consistent with predictions made from the nucleotide sequence of the speA gene according to Weeks and Ferretti and different from the sequence published by Johnson et al.

Cloning and expression of streptococcal pyrogenic exotoxin A and staphylococcal toxic shock syndrome toxin-1 in Bacillus subtilis

The genes encoding streptococcal pyrogenic exotoxin type A (SPE A) and staphylococcal toxic shock syndrome toxin-1 (TSST-1) were stably cloned and expressed in Bacillus subtilis. In the non-pathogenic Bacillus background, the recombinant speA clone expressed 32-fold more SPE A than the native streptococcus, and similarly, the recombinant plasmid harboring tst expressed 4-fold more TSST-1 in Bacillus than in the native Staphylococcus aureus. The Bacillus-derived products were secreted into the culture fluid, were resistant to proteolytic degradation and their biological activities mimicked native preparations.

Mitogenic activity of extracellular cationic products produced by group A streptococci; analysis of the lymphocyte response

The cationic fraction (isoelectric point greater than 8.5) of supernatant products of group A streptococcal cultures exerted a strong mitogenic effect on human peripheral lymphocytes at concentrations as low as 1 ng/well. Incorporation rates were highest at concentrations of 1-10 micrograms; rabbit peripheral lymphocytes also responded strongly, only a weak response was seen with mouse peripheral lymphocytes and rabbit thymocytes. Purified OKT4 positive (T helper) and OKT8 positive (T suppressor) lymphocyte subpopulations both responded, the former more strongly. Although accessory cells (monocytes) were not absolutely necessary, in their presence higher incorporation of 3H-thymidine was observed. Isolated B cells did not respond.

High production of the acquired immunodeficiency syndrome virus (lymphadenopathy-associated virus) by human T lymphocytes stimulated by streptococcal mitogenic toxins

Purified streptococcal mitogens (SMs) including erythrogenic exotoxin were compared with phytohemagglutinin (PHA) for their ability to sustain lymphadenopathy-associated virus (LAV) replication after the stimulation of normal human peripheral blood mononuclear cells and purified CD4+ and CD8+ T cells infected with LAV. Both SM and PHA supported LAV production in peripheral blood mononuclear and CD4+ cells but not in CD8+ cells. LAV production assessed by the assay of reverse transcriptase in cell supernatants appeared earlier after stimulation with SM and was 6- to 10-fold greater than after stimulation by PHA.

Streptococcal pyrogenic exotoxin type A (scarlet fever toxin) is related to Staphylococcus aureus enterotoxin B

The nucleotide sequence of the gene encoding group A streptococcal pyrogenic exotoxin type A (SPE A) was determined by the dideoxy chain termination method. The first 30 residues of the translation product represented a hydrophobic signal peptide. The mature protein was 220 amino acids in length and had a molecular weight of 25,805. It has significant protein sequence homology with Staphylococcus aureus enterotoxin B but not with other proteins in the Dayhoff library.

Cell wall preparation consisting of group A carbohydrate and peptidoglycan moieties from Streptococcus pyogenes activates murine B lymphocytes

Cell walls from Streptococcus pyogenes strain Sv (Group A, M type 3) were lysed with M1 endo-N-acetylmuramidase, and the group A-specific carbohydrate antigen was purified by Sephadex G-100 gel filtration. The initial eluting antigen (M1gA) peak was assessed for mitogenic and polyclonal lymphocyte-activating properties in murine spleen cell cultures. Good mitogenic responses were induced over a broad dose range (1-100 micrograms) with M1gA in both BALB/c and C3H/HeJ splenic cultures. Similar mitogenic responses were induced in nude (nu/nu) and nu/+ splenic cultures, suggesting that M1gA is a B cell mitogen. The M1gA induced anti-trinitrophenyl, anti-sheep erythrocytes, and anti-horse erythrocytes polyclonal plaque-forming cell responses in splenic cell cultures. Studies with purified splenic B cells and M1gA suggest that the mitogenic responses were indeed thymic independent. These studies clearly indicate that native group A carbohydrate antigen is a B cell mitogen and polyclonal B cell activator.

Tissue cages for study of experimental streptococcal infection in rabbits. II. Humoral and cell-mediated immune response to erythrogenic toxins

Infection of rabbits with erythrogenic toxin producing streptococcal strains caused a marked increase of humoral antibodies, which was detected by immunoprecipitation and ELISA. An antibody response directed towards the erythrogenic toxin type A was demonstrated by fused rocket immunoelectrophoresis. All toxinogenic reference strains produced ET type A under in vivo conditions despite that this toxin was not always demonstrated under in vitro conditions. The infection resulted in an increase of mitogenic response of peripheral lymphocytes to the initial nonspecific mitogenic erythrogenic toxins, whereas the Con A stimulation was depressed starting 14 days after infection and lasting during a period of 90 days. Since a normal antibody response was evoked, it seems likely that the T helper cell function was not affected.

The gene for type A streptococcal exotoxin (erythrogenic toxin) is located in bacteriophage T12

The infection of Streptococcus pyogenes T25(3) with the temperate bacteriophage T12 results in the conversion of the nontoxigenic strain to type A streptococcal exotoxin (erythrogenic toxin) production. Although previous research has established that integration of the bacteriophage genome into the host chromosome is not essential for exotoxin production, the location of the gene on the bacteriophage or bacterial chromosome had not been determined. In the present investigation, recombinant DNA techniques were used to determine whether the gene specifying type A streptococcal exotoxin (speA) production is located on the bacteriophage chromosome. Bacteriophage T12 was obtained from S. pyogenes T25(3)(T12) by induction with mitomycin C, and after isolation of bacteriophage DNA by phenol-chloroform extraction, the DNA was digested with restriction enzymes and ligated with Escherichia coli plasmid pHP34 or the Streptococcus-E. coli shuttle vector pSA3. Transformation of E. coli HB101 with the recombinant molecules allowed selection of E. coli clones containing bacteriophage T12 genes. Immunological assays with specific antibody revealed the presence of type A streptococcal exotoxin in sonicates of E. coli transformants. Subcloning experiments localized the speA gene to a 1.7-kilobase segment of the bacteriophage T12 genome flanked by SalI and HindIII sites. Introduction of the pSA3 vector containing the speA gene into Streptococcus sanguis (Challis) resulted in transformants that secreted the type A exotoxin. Immunological analysis showed that the type A streptococcal exotoxin produced by E. coli and S. sanguis transformants was identical to the type A exotoxin produced by S. pyogenes T25(3)(T12). Southern blot hybridizations with the cloned fragment confirmed its presence in the bacteriophage T12 genome and its absence in the T25(3) nonlysogen. Therefore, the gene for type A streptococcal exotoxin is located in the bacteriophage genome, and conversion of S. pyogenes T25(3) to toxigenicity occurs in a manner similar to the conversion of Corynebacterium diphtheriae to toxigenicity by bacteriophage beta.

Alteration of murine immune response by Pseudomonas aeruginosa exotoxin A

Pseudomonas exotoxin A has been implicated as a possible virulence factor in Pseudomonas infections. This toxin has a direct cytotoxic effect on a number of cell types, including macrophages and their precursors, and therefore may affect other cells of the immune system. NFR/N(H-2q) (+/nu or nu/nu) mice were immunized with either T-dependent or T-independent antigens along with various doses of exotoxin A. The immune response was then assayed by a modification of the Jerne plaque assay. Exotoxin A induced a dose-dependent suppression of the in vitro and in vivo immune responses to T-dependent and T-independent antigens in immunocompetent +/nu mice. However, in NFR/N nu/nu mice, suppression of the immune response to the T-independent antigen trinitrophenylated-Ficoll was not observed. Instead, a marked enhancement of the response was observed at doses of 100 and 10 ng of exotoxin A. Removal of T-cells with anti-Thy 1.2 antiserum plus complement before antigen and exotoxin A stimulation in +/nu mice results in abrogation of the suppression. These data suggest that Pseudomonas exotoxin A exerts an effect on both B- and T-lymphocyte populations to modulate the immune response and that this activity may be one facet of the pathogenic effects of this toxin.

Group A streptococcal phage T12 carries the structural gene for pyrogenic exotoxin type A

The structural gene for group A streptococcal pyrogenic exotoxin (SPE) type A was cloned into E. coli. DNA fragments used for cloning the toxin gene were isolated from bacteriophage T12. Toxin, present in cell lysates of E. coli clones, immunoprecipitated with antisera raised against purified SPE type A and formed a line of identity with streptococcal-derived A toxin. The cloned toxin shared the following biological activities with streptococcal A toxin: Pyrogenicity; enhancement of host susceptibility to lethal endotoxin shock; nonspecific lymphocyte mitogenicity; and alteration of immunoglobulin production. The physical location of the toxin gene on the phage T12 genome was determined.

A physical map of the group A streptococcal pyrogenic exotoxin bacteriophage T12 genome

A physical map of group A streptococcal bacteriophage T12 was constructed with restriction endonucleases Sal/I, PstI, and EcoRI. The map is circularly permuted with a total length of 36.0 kb. Sub-molar quantities of certain restriction fragments, some of very precise MW and some of heterogeneous MW, were observed. This observation, together with mapping data, suggests that DNA packaging is initiated at a precise site on a concatemeric precursor and proceeds for a limited number of rounds.

Effects of carrier ampholyte contamination on the biological and biochemical properties of streptococcal pyrogenic exotoxin type C

Three streptococcal pyrogenic exotoxins (SPEs), designated as SPE A, B, and C, have been purified and characterized. Routine purification of the SPEs includes the technique of isoelectric focusing. An earlier study showed that the removal of commercial carrier ampholytes (Ampholines) from SPE was difficult. The physiochemical properties of SPE C were previously reported; however, the SPE C preparation used in those experiments was contaminated with Ampholines. As an alternative to Ampholines, we used simple buffers to generate the isoelectric focusing pH gradient and used this SPE C in a comparative study to evaluate the effects of Ampholine contamination on the biological and biochemical properties of this toxin. We found that Ampholine contamination overestimates protein concentration; consequently, the biological activity of SPE C was actually greater than reported. The most serious effect of Ampholines in SPE C was on amino acid analysis. The presence of Ampholines causes an apparent increase in neutral amino acids and a decrease in basic amino acids.

Tissue cages for study of experimental streptococcal infection in rabbits. I. Production of erythrogenic toxins in vivo

Tissue cages implanted subcutaneously were used to infect rabbits with erythrogenic toxin (ET) producing streptococci. The in-vivo production of ET was followed during the infection by immunoprecipitation analyses of the tissue cage fluid (TCF). ET types A and C were mainly detected during the first week of infection, but, as late as 4 weeks after the inoculation, ET was occasionally found in TCF. The nonspecific mitogenic activity of ET on human lymphocytes was also used as a biological marker to recognize ET in TCF. Mitogenic activity was detected in 90% of samples during the first week. In order to characterize the mitogenic material released by growing streptococci, TCF was electrofocused in polyacrylamide gel. The eluates of sliced gels were checked for mitogenic activity and compared with a purified ET preparation containing ET types A and C. It could be verified that ET type A was produced under in-vivo conditions by strains NY-5 and SF130, while ET type C was produced by strain T18. Differences between production of toxins in vitro and in vivo might be of significance for the understanding of the pathogenetic mechanisms in streptococcal infection.

Differences in lymphoproliferative responses to the bacterium Actinomyces viscosus in various mammalian species

A water-soluble extract of Actinomyces viscosus (AVS) was tested for its capacity to induce DNA synthesis in lymphocytes from man, monkeys, mice and guinea pigs. The results indicated that the AVS induced an in-vitro lymphoproliferative response, as assessed by tritiated thymidine incorporation, in mouse-spleen cells, in the majority of human peripheral blood samples tested and in macaque monkey spleen cells. The AVS also elicited a blastogenic response from spleen, lymph node and peripheral blood lymphocytes from guinea pigs immunized with A. viscosus. The AVS did not elicit a lymphoproliferative response from human-cord blood cells, monkey peripheral blood lymphocytes, or peripheral blood and spleen lymphocytes from non-immunized guinea pigs. Thus there was a difference in the ability of A. viscosus to induce DNA synthesis in lymphocytes from the different animal species tested.

Enzyme-linked immunosorbent assay for detection of type A streptococcal exotoxin: kinetics and regulation during growth of Streptococcus pyogenes

We describe the detection and quantitation of type A streptococcal exotoxin (erythrogenic toxin, streptococcal pyrogenic exotoxin) by an enzyme-linked immunosorbent assay. This sensitive and specific technique detected microgram amounts of type A exotoxin and was useful for studying the kinetics and regulation of type A exotoxin production during the growth of Streptococcus pyogenes NY5. Maximum production of type A exotoxin was observed during the mid-log phase of growth, similar to the production of other streptococcal extracellular products. When S. pyogenes NY5 was grown at 42 degrees C, decreases in both growth and type A exotoxin production were observed. The results obtained when we studied the influence of nutrient additives and metal ions on the production of type A exotoxin led to the conclusion that none of these factors significantly affected type A exotoxin synthesis and that regulation was constitutive.

Staphylococcal scarlet fever: role of pyrogenic exotoxins

Staphylococcal pyrogenic exotoxin (PE) types A and B were tested for their role in production of a scarlatiniform rash. The PEs elicited minimal skin reactions after intracutaneous injection into animals not presensitized to the toxins. In contrast, erythematous injection into animals not presensitized to the toxins. In contrast, erythematous and edematous rashes were produced after administration of either PE to animals presensitized to homologous toxin. After 3 to 4 days, the erythematous areas showed membranous desquamation. Staphylococcal PEs also enhanced delayed and Arthus hypersensitivity skin reactions developed against unrelated proteins; the reactions subsequently desquamated. In addition, animals previously sensitized to either staphylococcal PE type developed scarlatiniform rashes after challenged with heterologous staphylococcal or any group A streptococcal PE. The data suggest that staphylococcal PEs produce scarlet fever-like rashes comparable to group A streptococcal PEs and that all PE types contain a common core moiety against which delayed hypersensitivity may be developed.

Purification and characterization of staphylococcal pyrogenic exotoxin type B

Staphylococcal pyrogenic exotoxin (PE) type B was purified and characterized biochemically and biologically. The exotoxin was purified from cell-free culture supernatant fluids by using differential precipitation with ethanol and resolubilization in pyrogen-free distilled water followed by preparative thin-layer isoelectric focusing. A final purification of 153-fold was achieved on the basis of the capacity of the exotoxin to produce fever. The toxin migrated as a homogeneous protein with a molecular weight of approximately 18 000 when tested with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Hyperimmune antisera raised against the purified exotoxin reacted with partially purified toxin in an immuno-diffusion assay to form a single precipitin line. The isoelectric point of the PE was estimated to be 8.5. Alanine was identified as the N-terminal amino acid. The exotoxin contained significant amounts of lysine but few aromatic amino acids. The PE was pyrogenic and enhanced host susceptibility to lethal shock and myocardial damage by endotoxin. In addition, the exotoxin was a potent nonspecific lymphocyte mitogen and suppressed immunoglobulin M synthesis against sheep erythrocytes.

Mitogenic activity of cytoplasmic membranes isolated from L-forms of Staphylococcus aureus

Cytoplasmic membranes of L-forms of Staphylococcus aureus exerted a strong mitogenic effect on splenocytes of athymic nude mice as well as normal mice, while a cytoplasmic fraction of the same bacteria did not show definite mitogenicity. The mitogenic principle(s) of the membrane fraction was resistant to treatment with trypsin and was heat stable (at 100 C for 10 min). The active principle(s) in the insoluble residue of the membrane fraction digested with trypsin was not extracted with cold acetone, but could be solubilized by extraction with a cold chloroform-methanol mixture (2:1, v/v). The mitogenic principle(s) in the extract was fractionated by silicic acid column chromatography. Among five fractions separated by chromatography, fractions eluted with chloroform-methanol mixtures (1:1 and 1:20, v/v) were found to be strongly mitogenic. The cytoplasmic membranes of the L-forms also exerted a definite mitogenic effect on guinea pig splenocytes, but not on the thymocytes.

Species-dependent response to streptococcal lymphocyte mitogens in rabbits, guinea pigs, and mice

Extracellular mitogen preparations from NY5 and S84 strains of streptococci induced different responses among rabbit, guinea pig, and mouse lymphocytes. Evidence of T-cell mitogenicity is presented.

Activation of murine T-suppressor lymphocytes by group A streptococcal and staphylococcal pyurogenic exotoxins

The effect of group A streptococcal pyrogenic exotoxin (PE) type C and staphylococcal PE on the in vitro antibody response to sheep erythrocytes was studied in cultures of mouse spleen cells. Both exotoxins suppressed the day 4 direct plaque-forming cell response when added to the cultures. The maximum suppression was obtained with 1.0 or 0.1 ng of toxin per culture, and the suppressive effect was reversed by addition of gangliosides to the cultures at the same time as the exotoxins. Preincubation of T lymphocytes for 4 days with either exotoxin resulted in the generation of a suppressor cell population, which produced dose-dependent suppression of the direct plaque-forming cell response when added to fresh sheep eyrthrocyte-activated splenocytes. The suppression obtained was not reversed by gangliosides indicating toxin carry-over was not responsible for the effect. B cells, preincubated with exotoxin, failed to suppress the direct plaque-forming cell response of fresh erythrocyte-activated spleen cells.

Inhibition of ribonucleic acid synthesis by group A streptococcal pyrogenic exotoxin

Group A streptococcal pyrogenic exotoxins (SPEs) A, B, and C and alpha-amanitin enhance host susceptibility to lethal endotoxin shock. The capacity of SPE C and alpha-amanitin to prepare rabbits for the enhancement phenomenon required pretreatment of the animals 1 to 2 h before giving endotoxin. Endotoxin clearance from the circulation of rabbits pretreated with either SPE C or alpha-amanitin was reduced. Even at the time of death, significant amounts of endotoxin remained in the circulation. It is proposed that the SPE and alpha-amanitin inhibit ribonucleic acid synthesis in Kupffer cells with concomitant alteration in reticuloendothelial clearnace function, allowing endotoxin to persist in the circulation and produce host injury. All three SPE types and alpha-amanitin inhibited ribonucleic acid synthesis by 50% or greater in whole liver cells. Kupffer cells, liver cell nuclei, and liver nuclear extracts; inhibition was observed liver cells from both mice and rabbits. The inhibitory effect by SPEs was dose dependent and was observed after as little as 15 min of preincubation with liver cells. The content of ribonucleic acid in liver nuclei of mice pretreated with either SPE C or alpha-amanitan was reduced, whereas total deoxyribonucleic acid and protein content remained unaltered.

Ganglioside and monosaccharide inhibition of nonspecific lymphocyte mitogenicity by group A streptococcal pyrogenic exotoxins

Group A streptococcal pyrogenic exotoxins (SPE) types A, B, and C are potent nonspecific lymphocyte mitogens. The mitogenicity of these exotoxins was inhibited by gangliosides and sialic acid, whereas concanavalin A was unaffected. The capacity of both concanavalin A and SPE-A to stimulate lymphocytes was suppressed by alpha-methyl-D-mannopyranoside. Galactose reduced the activity of SPE-C. The sugars, glucose, N-acetylglucosamine, alpha-methyl-D-glucopyranoside, and fucose, did not affect SPE mitogenicity.

Natural phosphorylation of group A streptococcal pyrogenic exotoxin type C

Group A streptococcal pyrogenic exotoxin (SPE) type C, produced by strain T18P grown in the presence of 32P, was separated from culture supernatant fluids by using alcohol precipitation. The resulting toxin (EtOH-1) contained 3 X 10(6) to 5 X 10(6) cpm of 32P per milligram of protein. The radiolabel migrated with SPE C during isoelectric focusing in polyacrylamide gels (pI 6.7) and double immunodiffusion, in which the toxin formed a line of identity with highly purified SPE C when reacted with hyperimmune antisera raised against SPE C. The EtOH-1 radiolabeled toxin was pyrogenic and had the capacity to enhance host susceptibility to lethal endotoxin shock. EtOH-1 toxin lost both radiolabel and biological activity after being treated with alkaline phosphatase. The nonspecific lymphocyte mitogenicity of purified unlabeled SPE C was stimulated by adenosine monophosphate but not adenosine, adenosine diphosphate, or adenosine triphosphate. Adenosine monophosphate may function as a cofactor of SPE C and contribute the phosphate group required for biological activity.

Reinterpretation of the Dick test: role of group A streptococcal pyrogenic exotoxin

Because of the association of the group A streptococcal pyrogenic exotoxins (SPEs) with erythrogenic toxin used in the classical Dick test, the involvement of the SPEs in production of erythematous skin reactions was assessed. Unless they had been presensitized, young adult rabbits failed to show skin reactions after intracutaneous challenged with SPEs. Rabbits presensitized to purified protein derivative exhibited enhanced skin reactivity when given purified protein derivative plus SPE C; the enhancement was neutralized by antiserum to SPE C. Rabbits sensitized to bovine serum albumin showed extensive red rash development resembling scarlet fever rashes when given bovine serum albumin containing SPE C. Desquamation occurred 5 to 10 days after injection. Animals sensitized to one SPE type showed enhanced skin reactivity to challenge with homologous or heterologous SPE types, indicating the presence of a cross-reactive determinant within the SPE molecules. Repeated challenge of SPE-sensitized animals with homologous toxin resulted in concomitant antitoxin production with reduction of the enhanced skin reactivities, until typical delayed-hypersensitivity skin reactions remained. The data indicate that, in addition to the toxic reaction previously described, SPEs enhance Arthus and delayed-hypersensitivity skin reactions. It follows that erythrogenic toxin represents the enhancement of acquired skin reactivity to streptococcal antigens by one or more SPE types. Therefore, the Dick test measures SPE-enhanced hypersensitivity to streptococcal products.

Nonspecific T-lymphocyte mitogenesis by pyrogenic exotoxins from group A streptococci and Staphylococcus aureus

Group A streptococcal pyrogenic exotoxins types A, B, and C and staphylococcal pyrogenic exotoxin were shown to be potent nonspecific T-lymphocyte mitogens. Adherent cell populations did not significantly affect the nonspecific mitogenicity.

Purification and physicochemical and biological characterization of a staphylococcal pyrogenic exotoxin

A staphylococcal pyrogenic exotoxin was purified and characterized biochemically and biologically. The organism producing the toxin was a group I Staphylococcus aureus strain which was isolated from a vaginal infection of a patient with mucocutaneous lymph node syndrome (Kawasaki's disease). The possible association of the toxin with the disease syndrome is discussed. The toxin was purified from cell-free culture supernatant fluids by means of differential precipitation with ethanol and resolubilization in pyrogen-free distilled water followed by preparative thin-layer isoelectric focusing. The pyrogenic exotoxin produced fevers in both rabbits and mice and enhanced host susceptibility to lethal shock and myocardial and liver damage by endotoxin. Also, the toxin was a potent nonspecific lymphocyte mitogen, stimulating rabbit spleen cells and human cord blood lymphocytes to proliferate. The toxin migrated as a homogeneous protein when tested with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (molecular weight, 12,000) and reisoelectric focusing (pI 5.3). Hyperimmune antisera raised against the purified toxin reacted with ethanol-precipitated toxin, using immunodiffusion to form a single precipitin arc. The toxin was distinguished from other staphylococcal toxins by a variety of methods. The amino acid composition was determined.