The Use of Streptococcal Antigens to Probe the Mechanisms of Immunity

Abstract

The difficulty to comprehend the immune response resides both in the complexity of antigens, in terms of linear structure and arrangement in space, as the eliciting signal and the complex molecular and cellular interactions that result in the induction and the expression of antibodies. In addition, every antibody response is the sum of many clonal responses, specific and cross-reactive. Hence, any study dealing with the expression of antibodies calls in the last analysis for means to separate the antibody forming clones and their products, the monoclonal antibodies (9). The analysis of myeloma proteins (37) as an alternative for antibodies with predetermined specificities can only be regarded as a substitute for the issue to be addressed -these substrates are the final products that rarely have known antigen specificity and cannot tell the story leading to their expression -until a unifying model will become available to resolve the structure-function relationship of antibodies, the connections between specific antibodies and correlating T cell receptor specificity, and the genetics of the immune response and of the antibody variable regions.A number of different antigen systems and of antibody models have been used to tackle these problems (18). Undoubtedly, the streptococcal group polysaccharide antigens have played a significant role in this line of research, since antibody responses of restricted heterogeneity to these bacterial cell wall antigens were reported (28,35), and could later be elicited at will and in a predictable fashion both in selectively bred rabbits and in certain inbred strains of mice (5,8, IS,29). No other antigen system has been applied for such a variety of studies until the monoclonal antibodies were generally made available by the hybridoma technique (25, 32).I t is the purpose of this review to point out the contributions made to immunology and to bacteriology by the system of antibodies of restricted heterogeneity This article was written on the basis of the special lecture delivered at the 56th Annual Meeting of Japanese Society for Bacteriology (Osaka, April 5-7, 1983). 823

Preparation and characterization of monoclonal antibodies to group-specific antigenic determinant of group a streptococcus polysaccharide

“…This may be due to different affinity of the examined MAb. Precipitating antibodies to A-PS are high-affinity, while non-precipitating are characterized by low affinity [8]. Presumably, the precipitating and non-precipitating antibodies are directed to different sites of polysaccharide chain, which is confirmed by our results.…”

“…MAb 96G10 may be similar to precipitating antibodies to A-PS which are directed towards repeated 13GlcNac moieties along the polysaccharide chain [8]. MAb 48B5 seem to be directed to a smaller determinant.…”

Platelet Aggregation Induced by Serotype Polysaccharides fromStreptococcus mutans

“…In addition, the RGPs could activate rabbit and human platelets by inducing shape changes. Interestingly, the RGPs of S. mutans share a common structural relationship with the group-specific polysaccharide antigens of Lancefield group A, C, and E streptococci and the RGP antigen of Streptococcus sobrinus (5,35).…”

Expression and Characterization of StreptococcalrgpGenes Required for Rhamnan Synthesis inEscherichia coli

“…The group-specific polysaccharide antigens of Lancefield group A, C, and E streptococci (3,26), the serotype-specific antigen of Streptococcus mutans (18,27), and the rhamnose-glucose polysaccharide (RGP) antigen of Streptococcus sobrinus (19) share a common structural relationship. The backbones of these polysaccharides are polymers of ␣1,2-and ␣1,3-linked rhamnose units.…”