Biomedical subjects

G Kronvall

Publications and source records attributed to G Kronvall.

At least 91 records · Page 5Linked to original sources

PubMed1984

Surface characteristics of group A streptococci with and without M-protein.

Twenty M protein-positive and eight M protein-negative strains of group A streptococci were investigated with respect to surface hydrophobicity and amount of lipoteichoic acid (LTA). Surface hydrophobicity as determined in polymer two-phase systems varied substantially between individual strains and there was no correlation to the presence of antiphagocytic M protein. The amount of LTA on the surface of the bacteria varied with hydrophobic affinity of the cells. Strains with a high content of surface LTA were found among both M-positive and M-negative streptococci. Cellular and extracellular LTA was estimated on six strains by the ability of hot phenol extracts and culture fluids to sensitize erythrocytes and by rocket immunoelectrophoretic quantitation. Differences in content of surface LTA did not correlate to differences in the total amount of cellular LTA. Pepsin digestion of M-positive group A streptococci at suboptimal pH resulted in a loss of M antigen whereas surface LTA and the hydrophobic interaction liability was retained. The results indicate that the degree of surface hydrophobicity as measured by two-phase partitioning is not correlated to either the type-specific or the antiphagocytic moiety of M protein. The results support the correlation between surface LTA and surface hydrophobicity of group A streptococci.

Antigens, Bacterial↗

PubMed1984

Interaction of thermally aggregated human IgG with bacteria.

Ninety-three bacterial strains, representing 16 Gram-positive and Gram-negative species, were tested for quantitative binding of 125I-labelled monomeric and thermally aggregated human IgG. Aggregated IgG bound to all bacterial species studied, in contrast to monomeric IgG, which interacted only with S. aureus, group A, C and G streptococci, viz. bacteria possessing previously described IgG-Fc receptors. A positive correlation was observed between binding of monomeric IgG and the uptake of thermally aggregated IgG (r = 0.92). Monomeric IgG inhibited effectively the binding of monomeric IgG but only partially the uptake of aggregates. Absorption with bacteria revealed that only a fraction of aggregated IgG could interact with bacteria lacking specific IgG-Fc receptors. A human group G streptococcus strain (G-148), tested with increasing amounts of immunoglobulin, was capable of binding at least ten times as much aggregates as monomeric IgG, implying binding to separate binding sites. These data indicate that polymeric IgG produced by thermal aggregation of human polyclonal IgG can interact with bacterial surface components found in most pathogenic microorganisms. This interaction seems to be less specific than the binding to previously described IgG-Fc receptors.

Escherichia coli↗

PubMed1984

Methodological aspects of Staphylococcus aureus peptidoglycan serology: comparisons between solid-phase radioimmunoassay and enzyme-linked immunosorbent assay.

In the present studies we compared the ability of two commonly used assays, solid-phase radioimmunoassay and enzyme-linked immunosorbent assay (ELISA), to detect human antibodies to Staphylococcus aureus peptidoglycan. ELISA was superior, with a reproducibility of 12.0%, as compared with 18.1% in solid-phase radioimmunoassay. Much lower serum dilutions could be used in ELISA. We also studied the effects of solubilizing the antigen by lysostaphin, lysozyme, or ultrasonication. Lysostaphin-treated peptidoglycan cannot be recommended since solid-phase radioimmunoassay could not distinguish positive from negative serum samples with this preparation. On the other hand, the sensitivity in both assays was high when peptidoglycan treated with lysozyme for 240 min or with ultrasonication for 30 min was used as antigen. The interassay correlation between solid-phase radioimmunoassay and ELISA was slightly better with sonicated peptidoglycan (correlation coefficient = 0.94, P less than 0.01), as compared with lysozyme-treated peptidoglycan (correlation coefficient = 0.76, P less than 0.01). We recommend the ELISA with sonicated peptidoglycan as antigen for use in routine serology.

Adult↗

PubMed1984

Purification and some properties of streptococcal protein G, a novel IgG-binding reagent.

Protein G, a bacterial cell wall protein with affinity for immunoglobulin G (IgG), has been isolated from a human group G streptococcal strain (G148). Bacterial surface proteins were solubilized by enzymatic digestion with papain. Protein G was isolated by sequential use of ion-exchange chromatography on DEAE-cellulose, gel filtration on Sephadex G-100, and affinity chromatography on Sepharose 4B-coupled IgG. The presence of protein G in various pools and fractions during the isolation was followed by their ability to inhibit the binding of radio-labeled IgG to G148 bacteria. A highly purified protein G was obtained. On polyacrylamide gel electrophoresis in sodium dodecyl sulfate, the apparent m.w. was 30,000, and on agarose gel electrophoresis the purified protein gave rise to a single band in the alpha 1-region. Protein G was found to bind all human IgG subclasses and also rabbit, mouse, and goat IgG. On the IgG molecule, the Fc part appears mainly responsible for the interaction with protein G, although a low degree interaction was also recorded for Fab fragments. IgM, IgA, and IgD, however, showed no binding to protein G. This novel IgG-binding reagent promises to be of theoretical and practical interest in immunologic research.

Bacterial Outer Membrane Proteins↗

PubMed1983

Different protein A immunosorbents may have different binding specificity for rat immunoglobulins.

Purified polyclonal immunoglobulin preparations representing the 4 rat IgG subclasses were tested for binding to Staphylococcus aureus protein A attached to 3 different solid phases (Staphylococcus aureus Cowan I bacteria, Sepharose CL4B and Sepharose 6MB). Protein A Sepharose CL4B showed higher reactivity with IgG1 and IgG2b than the staphylococci, whereas protein A Sepharose 6MB showed a lower uptake of these subclasses. No differences were seen for IgG2a and IgG2c. Protein A on different solid phases cannot be used interchangeably without confirmation of binding specificity.

Animals↗

PubMed1983

Alternative non-immune F(ab')2-mediated immunoglobulin binding to group C and G streptococci.

We tested 140 bacterial strains representing 19 different species for binding of purified radiolabelled F(ab')2 fragments prepared by pepsin digestion of polyclonal and monoclonal human IgG. Both polyclonal and monoclonal F(ab')2 fragments showed positive binding to group C and G streptococci with maximum uptake levels of 50% and 85%. Binding was obtained both with fresh bacteria and with organisms stabilized by heat treatment. F(ab')2 fragments of two human IgG1 myeloma proteins with anti-staphylolysin specificity showed a similar binding pattern. IgG present in normal human serum inhibited the uptake of F(ab')2 fragments, whereas albumin and fibrinogen and purified Fc fragments prepared by papain digestion of polyclonal IgG and monoclonal IgG1 did not show such capacity. Fourteen human myeloma proteins representing IgA, IgM and the four IgG subclasses were tested for inhibiting capacity. Reactivity was noted with at least one myeloma protein within each IgG subclass but not with IgA or with IgM monoclonal proteins. Normal rabbit serum was as inhibitory as normal human serum, whereas dog serum was less reactive. These data demonstrate that group C and G streptococci carry a heat-stable surface component interacting with the F(ab')2 portion of the IgG molecule. The results suggest that the reactive site on the immunoglobulin molecule may reside in the more constant part of the variable domain. This new reactivity is different from the previously known non-immune reaction involving the IgG Fc portion. This alternative non-immune reactivity is analogous to but distinct from the alternative protein A reaction in Staphylococcus aureus.

Antibodies, Monoclonal↗

PubMed1983

Antibody response to alpha- and betahemolysin from Staphylococcus aureus in patients with staphylococcal infections and in normals.

One hundred and nineteen patients with S. aureus infections and 22 patients with non-S. aureus septicemia were investigated for anti-alpha hemolysin antibodies using a radioimmunoassay (RIA). As compared to 16- healthy controls, patients with S. aureus endocarditis, septicemia, chronic osteomyelitis and recurrent furunculosis showed significantly higher antibody levels, while the non-S. aureus septicemia group showed normal levels. Corresponding results were obtained using the conventional anti-staphylolysin (ASTA) test. Only patients with recurrent furunculosis had significantly elevated anti-beta hemolysin antibody levels assessed by RIA, in comparison with healthy controls. The highest antibody levels were found in furunculosis patients infected with S. aureus strains which were high producers of beta hemolysin. The results indicate that furunculosis patients do not have a defective serological response against S. aureus beta hemolysin.

Antigen-Antibody Reactions↗

PubMed1983

Demonstration of a receptor for mouse and human serum albumin in Streptococcus pyogenes.

A new type of surface receptor for serum albumin was detected in strains of Streptococcus pyogenes (group A). This receptor, called type e, was different from albumin receptors in other streptococcal species. Only mouse and human serum albumin was bound to the receptor. The albumin-binding capacity was high: 2 X 10(8) bacterial organisms bound 11 micrograms of mouse albumin. The receptor was stable even when treated at 100 degrees C for 5 min. Binding of albumin was not mediated by lipoteichoic acid (LTA) because of lack of correlation to surface LTA, restricted albumin reactivity, and positive binding in presence of 2% Tween 20. Presence of albumin receptor type e correlated to presence of M-protein as measured by growth in the bactericidal test. All 51 M-protein positive group A streptococcal strains tested could bind mouse albumin whereas only 3 out of 8 M-protein negative strains showed positive binding (P less than 0.001). The sensitivity to trypsin digestion suggests that the albumin receptor is of protein nature or mediated by a protein.

Animals↗

PubMed1983

Solid-phase radioimmunoassay of immunoglobulin G antibodies to Staphylococcus aureus peptidoglycan in patients with staphylococcal infections.

A solid-phase radioimmunoassay (SPRIA) for determination of antibodies against S. aureus peptidoglycan was used for serological diagnosis of staphylococcal infections. Elevated IgG antibody levels were found in 21/21 patients with S. aureus endocarditis and in 10/24 patients with S. aureus septicemia. Two patients with streptococcal and one patient with pneumococcal septicemia showed elevated antibody levels as well, probably due to cross reactions between peptidoglycans of different bacterial species. In cases of chronic osteomyelitis caused by S. aureus, 12/33 patients showed elevated antibody levels while all patients with recurrent furunculosis had normal antibody levels. Anti-peptidoglycan antibodies were also found in all healthy controls (n = 160) but at lower levels. This might explain the rapid booster response of IgG antibodies found in 73 per cent of patients with S. aureus endocarditis already within 10 days after the first symptoms. The best clinical value of the assay seems to be in separating S. aureus endocarditis from uncomplicated septicemia.

Adolescent↗

PubMed1983

Lipoteichoic acid is the major cell wall component responsible for surface hydrophobicity of group A streptococci.

The contribution of lipoteichoic acid (LTA) to the hydrophobic surface properties of group A streptococci was investigated in aqueous dextran-polyethylene glycol two-phase systems. Enzymatic digestions were performed to characterize the hydrophobic surface structure. The results obtained indicated that LTA is a major factor responsible for the hydrophobic character of the cell surface of group A streptococci. This was further supported by the similarity of partition in polymer two-phase systems between whole group A streptococci and tritiated LTA extracted from a group A streptococcal strain. Surface LTA was also determined on intact organisms by a new method measuring the adsorption of antibodies to LTA to the bacterial surface. A correlation was found between the content of surface LTA and the hydrophobicity of the group A streptococci. We conclude that surface-associated LTA is the major factor determining surface hydrophobicity of group A streptococci.

Antigens, Bacterial↗

PubMed1983

Electron microscopic localization of receptors for aggregated beta 2-microglobulin on the surface of beta-hemolytic streptococci.

The presence and location of receptors for aggregated human beta 2-microglobulin (beta 2m) on the surface of group A, C, and G streptococci were studied by electron microscopic techniques. Ferritin-conjugated aggregates of human beta 2m were used in direct binding experiments. Ferritin-conjugated antibodies against beta 2m were employed in a two-step indirect binding assay where the streptococci were incubated with unlabeled beta 2m aggregates before the addition of antibodies. Similar results were obtained with these two methods. Among tested group C and G strains, some showed binding of beta 2m, whereas others were negative. In group A streptococci, beta 2m binding was localized to filamentous structures typical of M protein. In two M protein-negative group A strains, the reactivity was heterogeneous, revealing a majority of unlabeled, but also some heavily labeled streptococci. Morphologically, these beta 2m-binding bacteria exhibited M protein-like projections in contrast to the smooth surfaces of unlabeled cells.

Cell Membrane↗

PubMed1983

Single-strain regression analysis for determination of interpretive breakpoints for cefoperazone disk diffusion susceptibility testing.

A novel approach for setting interpretive breakpoints in disk diffusion antibiotic susceptibility testing according to determined minimum inhibitory concentration (MIC) limits is described, using the method of single-strain regression analysis. The procedure was tested on reference strains Staphylococcus aureus (ATCC 25923), Streptococcus faecalis (ATCC 29212), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853), using published results from cefoperazone disk diffusion experiments. The correlation between logarithm of the disk content and inhibition zone diameter squared was linear, excluding three endpoint values. When constants A and B in the new regression line equation were calculated for the four strains, all four showed different regression lines. Zone diameters corresponding to various MICs were calculated for a disk content of 75 micrograms. The values obtained for the four strains were 20.1, 20.9, 24.9, and 25.8 mm, respectively, for an MIC of 16 micrograms/ml, and 15.7, 15.7, 22.3, and 17.9 mm, respectively, for an MIC of 64 micrograms/ml. The following zone diameter breakpoints were determined for the "I" (intermediate) category, using a 75-micrograms disk: S. aureus, 18 to 15 mm; S. faecalis, 23 to 13 mm; E. coli, 20 to 17 mm; and P. aeruginosa, 20 to 17 mm.

Bacteria↗

PubMed1983

The clinical significance of serological methods in the diagnosis of staphylococcal septicaemia and endocarditis.

In comparison to healthy controls we have found that patients with endocarditis and septicaemia caused by Staphylococcus aureus show significantly higher antibody levels against either S. aureus peptidoglycan, crude staphylococcal antigen or alpha-toxin. The serological methods used in these studies were radio-immunoassays. These results have now been further evaluated concerning their clinical significance. The occurrence rate of S. aureus endocarditis and septicaemia at the clinic was 0.36% and 2.0%, respectively, during the study period. In spite of relatively high levels of test specificities, 93.8-96.9%, the predictive values for positive test results were low, 2.7-23.2%. Using the PG-assay, satisfactory predictive values of 100% together with a sensitivity of 95.2% could nevertheless be reached in the screening for S. aureus endocarditis, if the upper normal limit was raised.

Antibodies, Bacterial↗

PubMed1982

beta 2-Microglobulin in saliva and its relation to flow rate in different glands in man.

The concentration of beta 2-microglobulin (beta 2-m) in parotid saliva and sera from 13 adult hypogammaglobulinaemic subjects and in parotid saliva from 7 normal adults was determined by radioimmunoassay. Parotid and submandibular/sublingual saliva was collected from four normal and one hypogammaglobulinaemic subject in unstimulated and stimulated samples, and concentrations of IgA and beta 2-m were determined. The beta 2-m concentration in parotid saliva from hypogammaglobulinaemic subjects was 0.50 mg/l (0.2-1.1) and in normal adults 0.41 mg/l (0.2-0.9). In parotid saliva, the concentration of beta 2-m was negatively correlated with the flow rate, whereas in submandibular/sublingual a positive correlation was seen. Serum levels of beta 2-m in hypogammaglobulinaemic subjects were within the normal range of healthy adults. Gel filtration of saliva separated beta 2-m from IgA and from high molecular weight agglutinins. Beta 2-m was eluted as one single peak.

Adult↗

PubMed1982

Fractionation of rat IgG subclasses and screening for IgG Fc-binding to bacteria.

The four IgG subclasses of the rat, IgGl, IgG2a, IgG2b and IgG2c, were purified from normal serum by a combination of protein A-affinity chromatography and DEAE-cellulose chromatography. Purified, radiolabelled preparations of IgG were tested for binding to Gram-positive bacteria representing five different Fc-receptor (FcR) types. Distinct rat subclass-specific Fc-binding was noted to bacterial species belonging to different Fc-receptor types. Staphylococcus aureus (FcR I) strains bind IgGl and IgG2c as shown by others. Group C and G Streptococci (FcR III) bind all four subclasses of rat IgG. Streptococcus zooepidemicus strains (FcR V) also bind all four subclases but only to a lower degree. Human group A Streptococci (FcR II) and bovine group G Streptococci (FcR IV) do not bind any of the rat IgG subclasses. Elution studies on two strains. Staphylococcus aureus, Cowan I, and human group G Streptococcus, G 148, showed that both thiocyanate and pH-elution might be useful for the fractionation of IgG subclasses bound to bacterial cells. The present work indicates the possible use of bacterial cells as solid-phase absorbents in immunological studies of rat IgG.

Animals↗

PubMed1982

Detection of Staphylococcus aureus antibodies in patients with S. aureus infections and in normal persons, using solid phase radioimmunoassay.

One hundred and thirteen patients with S. aureus infections, eight patients with non-S. aureus septicemia and 167 normal controls were investigated by solid-phase radioimmunoassay for staphylococcal antibodies. All serum samples tested had measurable antibodies, including the normal controls. The test could differentiate the patients group with S. aureus endocarditis from patients with other S. aureus septicemia, as well as from normal controls, as the endocarditis group had significantly higher antibody levels. Patients with non-bacteremic S. aureus infections, such as osteomyelitis and recurrent furunculosis, showed a wide range of antibody levels, 1/3 and 1/4 of the patients, respectively, showing high levels comparable to the endocarditis patients. Among normal controls, high antibody levels were found in 13 per cent.

Antibodies, Bacterial↗

PubMed1982

Isoelectric points and surface hydrophobicity of Gram-positive cocci as determined by cross-partition and hydrophobic affinity partition in aqueous two-phase systems.

Thirty-nine streptococcal strains belonging to groups A, C, and G and 12 staphylococcal strains were investigated with respect to surface charge and hydrophobicity. Isoelectric points of the bacteria were determined by cross-partition experiments in dextran-polyethylene glycol two-phase systems containing charged polymers. The results obtained indicate that group A, C, and G streptococci have isoelectric points of pH 3.75 +/- 0.15 standard deviation. Staphylococci show an isoelectric point of around pH 2 and thereby differ markedly from the streptococci. Pretreatment of bacteria with human serum resulted in a significant change in the isoelectric points of streptococci. In a second series of experiments, an aqueous dextran-polyethylene glycol two-phase system containing polyethylene glycol palmitate or stearate was used to study the hydrophobic surface properties of the bacterial cells. The partition of the staphylococci was not influenced by the addition of up to 1% (wt/wt) polyethylene glycol palmitate or stearate, whereas the streptococci showed a large variation in affinity for polyethylene glycol-bound hydrophobic groups. The bacterial strains included in the study were also tested for uptake of human serum proteins. A positive correlation was found between the hydrophobic affinity of group A streptococci and the density of receptors for aggregated beta-2-microglobulin.

Blood↗

PubMed1982

Receptor in group C and G streptococci detects albumin structures present in mammalian species.

The presence of albumin structures with the capacity to bind to a surface receptor in group C and G streptococci was studied in serum samples from 45 mammalian species representing 15 different orders, using an inhibition assay. The ability of animal sera to inhibit the uptake of radiolabeled human serum albumin by the streptococci indicated the presence of such albumin structures. Positive reactions were found in species of most orders tested, with Marsupialia as a notable exception. All Carnivora sera tested were strongly positive. In some orders such as Artiodactyla both positive and negative species were identified. Serum samples from 62 bird species representing 15 orders and from 5 fish species were also tested in the inhibition assay. None of these serum samples was capable of inhibiting the uptake of human serum albumin by streptococci. Some differences were also noted in the results obtained with group C and G streptococci from human and bovine sources, respectively, indicating the presence of two types of receptors. The present studies suggest a phylogenetic origin of albumin structures with affinity for the streptococcal receptor to a period after the divergence of Marsupialia from the other mammalian orders.

Animals↗