Flagellin produced in plants is a potent adjuvant for oral immunization

The aim of this study was to produce adjuvant with high biosafety, efficacy and low cost. Towards this goal, the plant Nicotiana benthamiana transient expression system was successfully used to express Salmonella typhimurium's flagellin (FljB). The yield of the expressed FljB was 280 mg per kg of fresh weight (FW) leaves. The lyophilized plant powder containing plant expressing FljB was mixed with ovalbumin (OVA) and used for oral immunization of BALB/c mice. The ELISA analysis showed higher and accelerated OVA-specific serum antibody responses in mice given the mixture when compared to animals receiving OVA alone. Furthermore, FljB elicited a mixed Th1/Th2 response as shown by the presence of specific anti-OVA IgG1, IgG2a and IgG2b isotypes. OVA-specific IgAs were also detected in mice given the mixture. Cell-mediated immune response to OVA was induced by FljB as determined by a spleen lymphocyte specific proliferation test. No immune response was generated against FljB. In conclusion, our results showed for the first time the production of FljB in plants and the efficient use of the crude lyophilized extract as an adjuvant for oral immunization.

Characterization of anti-irradiation-denatured ovalbumin monoclonal antibodies. Immunochemical and structural analysis of irradiation-denatured ovalbumin

Five monoclonal antibodies (OVA-01, -02, -03, -04, -06) produced against irradiated ovalbumin were investigated in relation to the conformational change in the ovalbumin molecule induced by irradiation with Cobalt-60 gamma-rays. Four antibodies (OVA-01, -02, -04, -06) recognized both native and irradiated ovalbumin, but OVA-03 reacted only with irradiated ovalbumin. These antibodies were classified by modified competitive ELISA, and their K(d) values were determined by the Klotz equation. Epitope analyses were also performed on OVA-03 using CNBr-cleaved peptide fragments from ovalbumin, and it was confirmed that OVA-03 bound to the fragment corresponding to residues Val173-Met196 of the ovalbumin molecule that consists of internal beta-sheet strand 3A and helix F1 containing one open turn. These results demonstrate that dramatic conformational changes in proteins can be induced or that some tertiary or secondary structures can be broken down by gamma-ray irradiation, producing new antigenic sites.

Proliferative responses towards native, heat-denatured and pepsin-treated ovalbumin by peripheral blood mononuclear cells from patients with hen's egg-sensitive atopic dermatitis

In order to clarify the mechanism of food-antigen recognition, the proliferative responses of peripheral blood mononuclear cells (PBMCs) to native, heat-denatured or pepsin-treated ovalbumin (OA) were investigated in 16 hen's egg-sensitive patients with atopic dermatitis (AD). Seven of them had hypersensitivity to boiled hen's egg and others had not. The responses of PBMCs to heat-denatured OA were lower than those to native OA in the patients without hypersensitivity to boiled hen's egg. However, there were no differences of the responses of PBMCs between heat-denatured OA and native OA in the patients with hypersensitivity to boiled hen's egg. Moreover, the reduction of the responses of PBMCs to pepsin-treated OA was recognized in six out of seven patients. The primary structure of OA did not change by heating or pepsin treatment according to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). These results suggested that the secondary structure of OA changed in connection with the reduction of the responses of PBMCs to denatured OA. In addition, we demonstrated the suppressive effect of anti-HLA-DR and anti-HLA-DQ monoclonal antibodies on the proliferative response of PBMCs to OA. The results suggested that the proliferative responses of PBMCs to OA were restricted by HLA-DR or HLA-DQ in hen's egg-sensitive patients with AD.

Mice ascites as a source of polyclonal and monoclonal antibodies

A large quantity of polyclonal anti-ovalbumin antibodies was obtained from mice by a simple modification of the method described by Kurpisz et al. (1988). In addition, the cells from ascitic fluid were used to produce monoclonal antibodies. Egg ovalbumin hyperimmunized BALB/c mice were injected successively with pristane, antigen and a non-antibody secreting myeloma cell line: the production of ascitic fluid containing antiovalbumin antibody activity was observed after 10-25 days. Cells from ascitic fluid were harvested, washed and fused together with polyethylene glycol to produce monoclonal antibodies. Two fusions were performed and a large number of monoclonal anti-ovalbumin antibodies was obtained. This method is simple, reproducible, allows many fusions to be obtained from one mouse, and allows the use of ascitic B cells rather than the more, frequently used splenic B cells.

Common antigenic properties of a g-type (goose) and a c-type (duck) egg white lysozyme: antibody responses in rabbits and mice

Embden goose (GEWL) and Barbary duck (DEWL) egg white lysozymes possess different amino acid sequences corresponding to the g-type and c-type, respectively. GEWL was shown to be a better immunogen than DEWL in both rabbits and mice. The antigenicity of the two lysozymes was tested using different techniques (i.e. indirect ELISA, inhibition tests and immunoabsorption experiments). Injection of either GEWL or DEWL into rabbits and mice induced both specific antibodies and cross-reacting antibodies. Moreover, anti-GEWL antibodies, in contrast to anti-DEWL antibodies, did not cross-react with hen egg white lysozyme (HEWL), a c-type lysozyme. While the structure of GEWL was not modified after binding to plastic, DEWL was denaturated, but it did keep some native epitopes. It was concluded that g-type and c-type lysozymes, which have different amino acid sequences, exhibit strong common antigenic properties.