| Research Abstract |
Recently, a monoclonal antibody E87 has been developed by Sawada et al. From the wide cross-reactivity againsy P. aeruginosa isolates, this antibody seems to be useful in immunotherapy for P. aeruginosa infection. In this project the occurrence and structure of E87 antigen were studied, and the following results are obtained.
(1) Rhamnose-rich polysaccharides were isolated from the O-polysaccharide fractions of three P. aeruginosa strains, IFO 3080 (Homma serotype M), IID 1020 (serotype G), and T424 (serotype G), after selective degradation degradation of the respective major O-antigens. On the basis of their chemical composition, measurement of ^1H - and ^<13>C-NMR spectra, and determination of optical rotatory, it is concluded that these polysaccharides have the same D-rhamnan structure, -3)-D-Rha(alpha1->2)-D-Rha(alpha1->3)-D-Rha(alpha1->, just like D-rhamnan from the strain IID 1008.
(2) In competitive ELISA, the above rhamnose-rich polysaccharide preparations as well as the D-rhamnan of strain IID 1008 inhibited, in the same extent, the binding of monoclonal antibody E87 to P. aeruginosa PAC 1 cells. Thus, the isolated polysaccharides are immunologically indistinguishable from the D-rhamnan.
(3) The enzyme assay system for GDP-D-rhamnose synthetase was developed, and it was shown that this enzyme occurs in nine (A, D, F, G, H, I, K, L, and M) of tested thirteen serotypes of P. aeruginosa. This enzyme distribution was closely correlated to the binding spectrum of monoclonal antibody E87 to these cells.
The above results strongly supports a possibility that E87 antigen is D-rhamnan- linked lipopolysaccharides. From their wide occurrence, the D-rhamnan-linked lipo polysaccharide may be a common antigen in P. aeruginosa.
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