Structural requirements for T-cell recognition of tyrosine-azobenzene-arsonate in the rat and mouse.

The ability of various analogues of tyrosine-azobenzenearsonate (ABA-tyr) to elicit responses in CBA mice and Lewis rats was studied in order to determine the essential features for association with Ia molecules on accessory cells and T-cell recognition. Exquisite specificity for the AsO3H2 group was found in the rat while substantial cross-reactivity was seen in the mouse when other acidic but not neutral groups were substituted. The azo linkage was found to be essential for specificity as was the phenolic ring of tyrosine. Reaction was found to be less specific for changes in the COOH group than the NH2 group of the tyrosine moiety indicating the associations of this end with Ia molecules was dependant on both charge and hydrophilic interactions and differed also between rat and mouse cells. It was concluded that an antigen's reaction with T-cells is affected by an epitope, determining specificity, an agretope, determining association with an appropriate Ia molecule, and an ability to be processed down to these minimal essential structures.