Identification of the CTL-2A12 minimal mHA epitope. (A) A peptide reconstitution assay was conducted to determine the concentration of peptides needed to stimulate CTL-2A12. Undecameric peptide (MEIFIEVFSHF), its C-terminal deleted decameric peptide (MEIFIEVFSH), and N-terminal deleted decameric peptide (EIFIEVFSHF) were synthesized and titrated by adding to the antigen-negative donor B-LCL. (B) Transcript of HMSD (encoding a 139-mer polypeptide) predicted by computer algorithm is indicated with ▩. ▨ indicates the presumed HMSD-v transcript region encoding a 53-mer polypeptide starting with an ATG codon and including the CTL-2A12 epitope. The location of the identified 2A12 epitope is shown below the HMSD-v cDNA. These 2 polypeptides have no homology because they are translated from different reading frames.