Antigenic determinant structural studies

A structural study on lipid A and the O-specific polysaccharide of the lipopoly-saccharide from a clinical isolate of Bacteroides vulgatus from a patient with Crohn s disease was conducted by Hashimoto and coworkers [39]. They separated two potent virulence factors, capsular polysaccharide (CPS) and lipopolysaccharide (LPS), from a clinical isolate of B. vulgatus and characterized the structure of CPS. Next, they elucidated the strucmres of O-antigen polysaccharide (OPS) and lipid A in the LPS. LPS was subjected to weak acid hydrolysis to produce the lipid A fraction and polysaccharide fraction. Lipid A was isolated by PLC, and its structure was determined by MS and NMR. 

Within the Cl oligosaccharide hapten it is likely that several different regions elicit complementary antibodies. Hopefully, further structural studies and the synthesis of a few oligosaccharides may help us identify an 07 antigenic determinant with even higher specificity for Salmonella serogroup Cl. 

G. Schiffman, E. A. Kabat, and W. Thompson, Immunochemical studies on blood groups. XXXn. Immunochemical properties of and possible partial structures for the blood group A, B, and H antigenic determinants, Biochem. J., 3 (1964) 587-593. 

Although myeloma antibodies provide a substantial advantage for structural studies of antigenic determinants in that they contain homogeneous combining sites, nevertheless the specificities available are limited. Only one myeloma with antiprotein specificity has been found d it is... 

The studies described above, as well as numerous others, have led to the conclusion that protein antigens may contain two general classes of determinant structures, namely, sequential and conformational. Sequential determinants would be those occurring in a linear conformation, as in the unfolded form of a protein, and conformational determinants would be those that are recognized by their homologous antibodies only when they occur in a particular conformation. The latter class would include determinants formed from amino acids that are located at distant points in the... 

Considering our familiarity with the pharmacological behavior of different sulfonamides, it is fjntstrating, indeed, to concede defeat no correlation appears to exist between their structural or functional characteristics and their tendency to become antigenic determinants. Table I - which has been compiled and averaged from multiple sources - presents biochemical and metabolic studies of various sulfonamides and notes, for each, the reported incidence of sensitization. We have been unable to find a common denominator. Even so, it is instructive to take a critical look at certain hypotheses which have been advanced. 

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