Immunization with syngeneic Sendai virus-infected cells induce no MHC-restricted antibodies but antibodies specific for H-2 class I determinants

To find out whether immunoglobulins are able to recognize foreign antigens in the context of syngeneic MHC determinants, an effort was made to trigger the production of MHC-restricted antibodies by syngeneic Sendai virus (SV)-infected cells using the spleen-fragment culture technique. Antibodies were found that mimicked MHC-restricted antibodies by recognizing MHC + SV better than MHC alone. However, the binding was not specific for SV and also occurred on mitogen-stimulated (SV^–) or influenza virus-infected cells. We describe the production of H-2 class I-specific lymphocytotoxic antibodies by primary B cells responding to syngeneic SV-infected cells. No viral-specific, H-2-restricted antibodies were found.     

Immunomodulative properties of conjugates composed of detoxified lipopolysaccharide and capsular polysaccharide of <Emphasis Type="Italic">Vibrio cholerae</Emphasis> O135 bound to BSA-protein carrier

O135 serotype Vibrio cholerae isolated from Slovak river was used as a source of surface polysaccharide antigens. Following detoxification procedure, fractions of polysaccharides were separated by size exclusion chromatography. Two resultant fractions were the capsular polysaccharide (M _w ∼ 197,000 Da) and the lipopolysaccharide fragment (M _w ∼ 13,300 Da). These materials were used for preparation of four novel glycoconjugates. Two of them containing detoxified lipopolysaccharide as antigen were prepared by original chemical method using the new biocompatible polymer as carrier of antigen. Additionally, other two conjugates were prepared by direct linking of capsular and detoxified lipopolysaccharide antigens to the protein carrier using adipic acid dihydrazide spacer. The immunogenicities (induced IgM, IgG, IgA antibodies) of all conjugates were determined by enzyme-linked immunosorbent assay. Polymer containing conjugates elicited higher levels of specific anti-lipopolysaccharide IgM and IgG antibodies in comparison with other conjugates without polymer carrier. Enhanced IgM vibriocidal activity of mice antisera was also evident here.     

Stepwise synthesis of methyl 4-O-[3-O-(β-d-xylopyranosyl)-β-d-xylopyranosyl]-β-d-xylopyranoside

The general properties and specificity of a dextran α-(1→2)-debranching enzyme from Flavobacterium have been examined in order to apply this enzyme to the structural analysis of highly branched dextrans. The optimum pH range and temperature were pH 5.5–6.5, and 45°, respectively. The enzyme was stable up to 40° on heating for 10 min, and over a pH range of 6.5–9.0 on incubation at 4° for 24 h. The effects of various metal ions and chemical reagents have also been examined. The debranching enzyme has a strict specificity for the (1→2)-α-d-glucosidic linkage at branch points of dextrans and related branched oligosaccharides, and produces d-glucose as the only reducing sugar. The degree of hydrolysis of the dextrans by this enzyme and the K_m value (mg/mL) were as follows: B-1298 soluble, 25.2%, 0.21; B-1299 soluble, 31.5%, 0.27; and B-1397, 11.8%, 0.91. The debranching enzyme thus has a novel type of specificity as a dextranhydrolase. We have termed this enzyme as dextran α-(1→2)-debranching enzyme, and its systematic name is also discussed.