Specificity and affinity of antibodies produced after in vitro and in vivo activation of B cells with lipopolysaccharide, DNP-lipopolysaccharide, flagellin and DNP-flagellin.
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The molecular weights of the flagellins of 13 strains of Escherichia coli, each with a different H antigen, were estimated using polyacrylamide gel electrophoresis. In each case only one major polypeptide was demonstrated, although some strains possessed apparently sheathed flagella. Considerable differences in the molecular weight of flagellin accompanied the previously described structural differences between flagella from strains with different H antigens. The relationship between flagellar diameter and the molecular weight of the corresponding flagellins was similar for both unsheathed and apparently sheathed flagella. Crosss-polymerization occurred between seed consisting of fragment of unsheathed flagella and flagellin solution from apparently sheathed flagella and vice versa. Co-polymerization of flagellin from unsheathed flagella and flagellin from apparently sheathed flagella was also demonstrated. These polymerization experiments indicate that the assembly pattern of flagellin molecules is probably the same in all E. coli flagella. The above and other evidence suggests that there is no true sheath, but that the differences in flagellar surface structure between different E. coli flagella are the result of differences in the superficial parts of the flagellin molecules.
The double-immunodiffusion technique and sodium dodecyl sulfate-polyacrylamide electrophoresis were used to demonstrate the presence of flagellin-like material strongly attached to ribosomes of Salmonella typhi Ty 2. This flagellin-like material contaminating the ribosome preparation interferes with the induction of antiribosome serum promoting the formation of antisera reacting either only with flagellin or in some cases with flagellin and ribosomes, but giving a very weak reaction with the latter. The interference is also observed when purified ribosomes from a nonflagellated mutant of S. typhi (S. typhi O-901) mixed with purified S. typhi Ty 2 flagellin are utilized as antigens. The antiribosome sera obtained with ribosomes from S. typhi O-901 have a considerably higher titer than those that are interfered with. These sera were able to react with ribosomes obtained from several related species and did not react with flagella-derived flagellin of S. typhi Ty 2.
We have studied the binding of M467, an IgA murine myeloma protein, to flagellin from seven species of Salmonella. It was found that M467 was reacting with antigenic determinants that were common to all the flagellins studied. These determinants were not related to serotypic antigens. Electronmicrographs of unreduced M467 showed a variety of polymeric species bound to flagella in a manner that could produce immobilization as well as agglutination and precipitation through cross-linking of antigenic determinants. Immunodiffusion in agar gel revealed that M467 was recognizing more than one group of peptide determinants on the flagellins studied. Passive hemagglutination inhibition and a solid phase radioimmunoassay provided evidence that there were differences in binding avidities between M467 and the various Salmonella flagellins studied. It was concluded that M467 is binding more than one specific group of antigenic peptide determinants on flagellin molecules. Flagellin from four of the seven species of Salmonella studied were deficient in one or more of these determinants.
Cutaneous hypersensitivity and antibody-producing capacity were assessed in patients with lepromatous leprosy with defective immunity, by immunizing them with monomeric flagellin from Salmonella adelaide. Results were compared with those of controls, matched for age and sex, derived from similar socioeconomic stratum, but without any defect of the immunological system. In contrast to the normal individuals, who showed Jones-Mote type of hypersensitivity, no lepromatous patient could mount any 'delayed-in-time' cutaneous hypersensivivity reaction against an intradermal challenge of monomeric flagellin. However, when immunized through the subcutaneous route, both groups could produce adequate amounts of specific serum antibody. In addition to this unique split tolerance found in all lepromatous patients, some patients showed low levels of 'natural' IgM antibody, reduced formation of specific antibody when immunized through the subcutaneous route, and incomplete maturation of IgG class of anti-flagellin antibody. When immunized by the intradermal route, however, production of both anti-flagellin antibody and maturation of IgG antibody was significantly inhibited in normal adults but not in lepromatous patients. Thus, contrary to the earlier concept of hyperactivity of the humoral immune apparatus in lepromatous leprosy, the present study detected B-cell hypofunction in some patients.
The authors obtained and studied immunologically flagellae of S. typhi and flagellins (monomeric and polymeric) obtained from them. Immunological activity of flagellin was the greater the higher the molecular weight of the preparation (the polymer molecules were the largest and the most immunogenic). There were revealed differences between the preparations according to the dependence of the immunizing effect on the dose and the capacity to induce synthesis of 19S- and 7S-antibodies. A sharp change of the immunogenicity of flagellin preparation following gel-filtration through sepharose 2B was demonstrated.
Purified flagellins derived from 16 strains of Bacillus subtilis were classified into at least five distinct groups on the basis of their reaction with antiflagellar filament antibody and antiflagellin antibody. This classification was in good accord with that derived independently on the basis of amino acid analyses of the flagellins. Flagellar antigenicity appears to provide a useful typological character in classifying B. subtilis strains.
Leucocyte adherence inhibition (LAI) was used to detect cell-mediated immunity of mice to Salmonella adelaide polymeric flagellin and its monomeric derivative. In the direct LAI technique, antigen inhibited the in vitro adherence to glass of peritoneal cells (PC) from antigen-primed mice which were capable of exhibiting in vivo delayed hypersensitivity reactions to the same antigen. In the indirect technique, primed PC exposed to antigen in vitro released a soluble factor, which inhibited the adherence of normal PC. Production of the factor was prevented by prior treatment of primed PC with anti-theta serum, indicating the participation of T-lymphocytes. The LAI reaction could be blocked by serum from mice which had been re-injected with antigen 72 h after a priming injection. Features of the production and biological properties of serum blocking activity suggest that it may be attributed to antigen-antibody complexes.
The characteristics of antibody-forming cell (AFC) progenitors lacking previous contact with specific antigen (virgin AFC progenitors) has been studied using sedimentation velocity and buoyant density separation for the investigation of physically distinct B-cell subpopulations. Functional characterization of isolated subsets was made using a quantitative adoptive immune assay for the IgM AFC progenitors responding to the antigen 4-hydroxy-3-iodo-5-nitrophenylacetic acid conjugated polymerized bacterial flagellin. Extensive heterogeneity is present among B lymphocytes, only some subpopulations of which exhibit AFC progenitor function. In the spleen of adult conventional CBA mice, atypically fast sedimenting cells of low buoyant density are active, while typical small B lymphocytes do not appear to be progenitors of IgM AFC. Spleen of adult specific pathogen-free (SPF), germfree, and athymic nude mice give similar results, although a minor population of typical slowly sedimenting dense cells are active in the latter two sources. Adult conventional bone marrow cells are as physically and functionally heterogeneous as splenic B cells, and although a significant proportion of AFC progenitor activity is found among dense, slowly sedimenting cells, most of the activity is among low density, faster sedimenting cells. In contrast to this situation in adult animals, where most of the unprimed AFC progenitors are large, atypical B cells, the spleens of neonatal mice provide a site where virgin AFC progenitors with the physical properties of typical small B lymphocytes are found. While being present in conventional and SPF neonatal spleens, these virgin cells are predominant in 7-day-old germfree mouse spleen. These findings suggest that the newborn virgin B cell is a typical small lymphocyte. However, few cells of this type are found in the adult animal. The unprimed AFC-progenitor population in the adult consists of large, fast sedimenting, low buoyant density, adherent cells, the physical properties of which are characteristic of activated B lymphocytes. It is suggested that these atypical cells are derived from the small newborn virgin B cell by the nonspecific effects of environmental antigenic stimuli.
Previous studies have defined 28 genes necessary for the synthesis of the flagellar apparatus of Escherichia coli K-12. This study analyzed the influence of the flagellar genes on the expression of the hag gene (structural gene for flagellin). To this end, a hag::Mu d(Apr lac) mutant which had the lac genes fused to the promoter of the hag gene was constructed. This allowed the measurement of hag gene expression by detection of beta-galactosidase activity. The following observations were made. (i) The hag gene was expressed constitutively in Fla+ cells. (ii) hag gene expression was positively regulated by flaA, FLAB, flaC, flaD, flaE, flaG, flaH, flaI, flaK, flaL, flaM, flaN, flaO, flaP, flaQ, flaR, flaV, flaW, flaX, flaY, flaZ, flbA, and flbB genes.hag-lac expression was not observed in strains with these fla mutations. (iii) The hag gene was expressed in mutants with flaS, flaT, flaU, and flbC defects. Therefore, these genes were not involved in regulation of hag gene transcription.
The work is devoted to the study of conditions required for the purpose of creation of standard and the most active preparations of erythrocytic H-diagnostic agents. The dependence of binding of the H-antigen by erythrocytes on the pH and the ionic power of the medium was investigated. It was demonstrated that in the process of erythrocyte sensitization with flagellin of great importance were electrostatic, hydrogen, and hydrophobic powers.
Flagellar preparations were obtained from 6 salmonellae strains by differential ultracentrifugation; they were characterized by morphological, immunochemical, and serological tests. The results of investigations showed that the preparations possessed high serological activity; somatic antigen admixture was insignificant. Flagellins extracted from the flagellae were used to prepare erythrocytic H-diagnostic agents. The results of their use in the examination of sera of healthy persons, and of those suffering from typhoid fever and salmonellosis indicated the expediency of using passive H-hemagglutination for diagnostic purposes.
As known, in typing of salmonellae H-antigens play an important role. Flagellae bear on their surface specific antigenic determinants, this permitting to differentiate H-antigens serologically. Monomeric form of H-antigens d,a,b,1,2 bear on their surface not only specific, but also common for the given H-antigens determinant group. Common flagellin determinant group in the flagella is screened.
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The antibody responses in serum and secretions obtained from the mucosal surfaces of the small intestine of rats immunized by a parenteral and intestinal route have been compared. Though no significant differences in the mean serum titres were found, the responses of animals immunized via the latter route to large doses of antigen were far less uniform. Apart from the first few days of the primary response, antibody activity was found in three major immunoglobulin classes (IgG2, IgA and IgM), irrespective of the route of immunization. Significant antibody activity appeared in the intestinal surface secretions only after two injections of antigen. In rats immunized parenterally the activity was found only in the IgG2 component. Whilst activity was found in both IgG2 and IgA fractions of the secretions obtained from intestinally immunized rats, it was predominantly of the IgG2 class. The possible significance of this observation is discussed.
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