FIG 4 .

During AIM, patients with mild or severe disease have selected different TCR Vβ families in the expanding cross-reactive IAV-M1 tetramer⁺ cells (analyzed directly ex vivo in PBMCs). This suggests that each group had different cross-reactive TCR repertoires prior to acute EBV infection, with differential effects on disease severity. (a) Directly ex vivo sorted CD8 T cells from PBMCs were costained with IAV-M1 tetramer and Vβ-specific MAbs. Both severe-AIM (n = 11) and mild-AIM (n = 8) patients had more diverse IAV-M1-specific TCR Vβ family use than HD-SP (n = 8), as calculated by the SDI (see Materials and Methods). (b, part i) Decreased use of commonly used Vβ19 in the IAV-M1-specific TCR repertoire in AIM patients compared to that in HD-SP. (b, part ii) The Vβ repertoire of IAV-M1-specific T cells differed between AIM patients (n = 19) and HD-SP (n = 18), with increased use of Vβ20, -9, -2, and -29, which are more often associated with EBV-BM responses. (c) IAV-M1-specific TCR Vβ repertoires differed between mild- and severe-AIM patients. Severe-AIM patients (n = 11) preferentially used Vβ4.1, while mild-AIM patients (n = 8) preferentially used Vβ2 and Vβ29. (d, part i) Disease severity correlated directly with specific TCR Vβ use in AIM patients, suggesting that it plays a role in the mediation of disease severity. There was a direct correlation between the frequency of IAV-M1-specific TCR Vβ4.1 use and the peak frequency of atypical T lymphocytes during AIM. (d, part ii) There was an inverse correlation between the frequency of IAV-M1-specific TCR Vβ2 use and the peak frequency of atypical T lymphocytes. The TCR Vβ frequency of each donor is based on the mean of the first four visits (to enhance reproducibility), except for Vβ4.1, where it is based on the mean of all visits. The Student t test was used to compare two groups, and one-way ANOVA with Sidak’s multiple-comparison test was used to compare more than two groups.