Cleavage of bacterial flagellin with proteolytic enzymes. II. Induction of enhanced delayed-type hypersensitivity to flagellin by peptic fragments of the protein

Escherichia coli-based cell free production of flagellin and ordered flagellin display on virus-like particles

Bacterial flagellin has been explored as a potential vaccine adjuvant for enhancing immune responses. In this article, we describe Escherichia coli-based cell-free protein synthesis (CFPS) as a method to rapidly produce soluble phase 1 flagellin (FliC) protein from Salmonella typhimurium. The yield was about 300 µg/mL and the product had much higher affinity for the TLR5 receptor (EC50 = 2.4 ± 1.4 pM) than previously reported. The flagellin coding sequence was first optimized for cell-free expression. We then found that the D0 domain at the C-terminus of flagellin was susceptible to proteolytic degradation in the CFPS system. Proteolysis was reduced by protease inhibitors, the use of protease-deficient cell extracts or deletion of the flagellin D0 domain. A human Toll-Like Receptor 5 (hTLR5)-specific bioactivity analysis of purified flagellin demonstrated that, although the D0 domain is far from the TLR5 recognition region, it is important for flagellin bioactivity. We next incorporated a non-natural amino acid displaying an alkyne moiety into flagellin using the CFPS system and attached flagellin to hepatitis B core virus-like particles (VLPs) using bioorthogonal azide-alkyne cycloaddition reactions. The ordered and oriented VLP display of flagellin increased its specific TLR5 stimulation activity by approximately 10-fold.

Immune deviation: a historical perspective

In this paper I have reviewed my early studies, between 1966 and 1976, on the phenomenon of immune deviation. Initially summarized are experiments with different forms of the flagellin antigen from Salmonella adelaide which established the inverse relationship between delayed-type hypersensitivity (DTH) and antibody formation. Based on the flagellin studies, many of the key factors which determine whether an antigen will induce either DTH or antibody formation were delineated. These factors are just as relevant today as they were 25 years ago. Subsequent analyses at the cellular level demonstrated that different T cell subsets mediate DTH and T cell help and maintain immune deviation by suppressor mechanisms. A number of fundamental questions raised by this early work remain unanswered and are discussed. These include the nature of the primary signalling events which initiate immune deviation, the role of B cells in the deviating process and the mechanism by which CD8+T cells suppress antibody production.

Regulation of delayed-type hypersensitivity (DTH) response to hen egg-white lysozyme (HEL)

Delayed-type hypersensitivity (DTH) can be demonstrated in A/J mice immunized with hen egg-white lysozyme (HEL) in complete Freund's adjuvant (CFA) by challenging primed animals in the ear with aqueous HEL. Normal A/J mice receiving soluble HEL derivative peptide, P-Ib, sequence 29-54 and 109-123 linked by a single S-S bond, 7 days prior to immunization with HEL showed much lower DTH response specific to the protein. The inhibition of DTH reactivity is due to active suppression and involves the generation of suppressor T-cells (Ts). Thus, the suppression induced with a single i.v. injection of P-Ib solution was able to be transferred into syngeneic recipients by the spleen cells from mice pretreated with P-Ib. These suppressor cells are T-cells, since their ability to suppress DTH is completely abrogated by treatment wit anti-Thy 1.2 and complement. Amongst HEL derivative peptides tested in the present study, only P-Ib could induce the tolerance.

Localization of antigenic activity and immunogenic capacity in different conformational domains of procollagen peptide

The antibody response to the amino-terminal CNBr peptide of sheep procollagen which consists of a globular and a collagenous segment, was studied in inbred strains of mice. The determinants reacting with antibody could be localized in the globular domain and were lost by reduction of disulfide bridges. The ability to induce an antibody response required the collagen-like sequences and was independent of the triple-helical conformation of this segment. The data were interpreted as indicating a different conformation dependence of hapten and carrier determinants.

Studies on delayed-type hypersensitivity to hen egg-white lysozyme. I. Peptide fragments of lysozyme inducing delayed-type hypersensitivity

Eleven peaks were separated by Carboxymethyl-cellulose column chromatography of peptic digest of lysozyme. Being stronger in antigenic activity two peaks of them, P-3 and P-9, were selected and purified further respectively by Amberlite IRC-50 and Sephadex G-50 column chromatography. As the results, PP-3 and PP-9 were obtained each as a single peak. For estimation of their capacities to induce delayed-type hypersensitivity, the antigen-induced 3H-thymidine incorporation, the migration inhibition of peritoneal cells and the delayed-type skin reaction were tested in guinea pigs immunized with native lysozyme or any of its fractions. PP-9 was almost as active as intact lysozyme in these capacities. On the other hand, PP-3 showed a slight inhibition of migration of peritoneal cells and no stimulation of 3H-thymidine incorporation into the lymph node cells. Moreover, the delayed-type skin reaction elicited by PP-3 was always weaker than that elicited by PP-9. Guinea pigs immunized with either PP-3 or PP-9 were also tested for these reactions. PP-9 and native lysozyme elicited these reactions in guinea pigs immunized with PP-9, but PP-3 did not. On the other hand, PP-3 and lysozyme elicited these reactions in those immunized with PP-3, but PP-9 did not. The possibility of recognition of two functionally different areas, one for production of the circulating antibody and the other for induction of delayed-type hypersensitivity, on the lysozyme molecule was discussed.