a, d PBMC from pediatric Pandemrix-associated NT1 patients (NT1; validation cohort) or pediatric Pandemrix-vaccinated healthy controls (C) were stimulated in culture with overlapping 15-mer peptides from influenza (A/reassortant/NYMC X-179A (California/07/2009 × NYMC X-157)(H1N1)) vaccine virus neuraminidase (NA) or nucleoprotein (NP), as indicated. b, c, e, f PBMC from NT1 patients (invariably HLA-DQB1*0602 positive; discovery and validation cohorts combined; HLA-DQB1*0602 homozygous NT1 patients marked with red dots) or HLA-DQB1*0602 positive (C/DQ6+) or negative (C/DQ6−) healthy controls were stimulated with single NA- or NP-derived peptides. The secretion of IFN-γ was measured by FMIA (protein). Results are expressed as the ratio between cytokine concentrations measured in peptide-stimulated and negative control samples (stimulation index). Statistical comparisons between groups were performed, using Kruskal–Wallis and Dunn’s multiple comparisons tests.