Figure 4.

HLA restriction and epitope mapping for S_811–831

(A) IFN-γ responses (ELISA) of 3 representative T cell clones with confirmed reactivity to S_811–831 presented by partially HLA-matched APCs (LG2, 9068, MN605); Bar graphs: means ± standard deviations, with responses to S_811–831 in black and DMSO control in gray.

(B) Antigen presentation blocking assays using T cell clones presented in A, and antibodies to DR, DQ, DP, and MHC class I. Inhibition indicated by colored arrows. Bar graphs: means ± standard deviations.

(C) Summary of T cell clone responses (clone number on top of graph) to S_811–831; color scale represents the ΔOD₄₅₀ (peptide-DMSO).

(D) Summary of blocking assay; color scale represents the percentage of inhibition.

(E) HLA alleles expressed by APCs shared with donors originating the T cell clones.

(F) Responses to a set of 11-mer peptides covering S_811–831; bars: response (%) of each truncated peptide relative to the full-length peptide. Representative clones for different reactivity patterns are shown; clone number on top; number of clones exhibiting a similar pattern in parentheses. Minimal sequence required to explain reactivity is highlighted.

(G) Summary of the 2 partially overlapping patterns observed in 32 clones (boxed in blue for DQ and yellow for DP).

(H) Location of minimal epitopes from (F), shown aligned with S_811–831 (color of lines match color of boxes; thickness of line represents approximate frequency of the pattern). Binding motifs for DQ5 and DP4 are shown as sequence logos.

(I) Normalized binding (half-maximal inhibitory concentration[IC₅₀]-positive control/IC₅₀ peptide) for truncated peptides to purified DQ5 or DP4 (see also Figures S2, S3 and S4).