Previous data from this laboratory have shown that fluorescein-specific cytotoxic T cells derived from naive mice are capable of distinguishing between different isomeric forms of the fluorescein hapten, as well as between the iodoacetamido-, isothiocyanate- and dichlorotriazinyl amino-fluorescein derivatives. In this report, we show that T cells derived from previously immunized animals, while demonstrating a stronger and more cross-reactive response overall, display identical fine specificity patterns to those of primary T cells for a panel of fluorescein homologues. We interpret this finding to indicate that the antigen receptor repertoires utilized by primary and secondary cytotoxic T cells are indistinguishable and that the enhanced response of memory as compared with naive CTL results from factors such as a higher density of cell surface receptors or receptor-associated molecules and/or a higher frequency of antigen-responsive T cells.
Animals Cells, Cultured