Antigenic Determinants in Cellular Reactions

Precise information on antigenic determinants reactive in T-cell activation, delayed hypersensitivity, and other manifestations of cellular immunity is quite limited. What has clearly emerged, however, is the notion that B- and T-cells react normally or at least frequently to different determinants on the same molecule. The classical example is that of Gell and Benacerraf (1959), where heat-denatured proteins lost their capacity to react with antibody against the native protein, whereas delayed reactions could be provoked with either native or denatured antigen. This finding was open to at least two possible interpretations namely that cellular immunity has a broader specificity than antibody responses, or that the structural entities serving as determinants in humoral and cellular immunity are not the same. 

CA-DNP. On the other hand, conjugates such as RAT-EACA-RAT induced delayed hypersensitivity or helper activity but no anti-RAT antibody. Thus RAT and DNP in this system are distinctive T-cell and B-cell determinants. 

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