Fig. 4

Characteristic alterations in CTLA-4 and Ki67-expression of VZV-specific T cells in patients with VZV-associated PFP. A Patients with PFP were subclassified according to a composite PFP-score based on the results of available routine clinical diagnostics (see Additional file 1: Table S1, n = 53, 2 patients with Guillain-Barré syndrome were not included) to allow determination of the most probable cause of PFP. Scores < − 1 were scored as idiopathic (n = 28), scores between ≥ − 1 and ≤ 1 as unclear (n = 17), and scores > 1 as inflammatory with or without detectable pathogen (n = 8, including 5 PFP-patients with VZV-induced skin disease (3 × zoster oticus, 1 × Ramsay Hunt zoster, 1 × with concomitant cervical (C2) zoster efflorescence)). B VZV-specific CD4 T cell levels of PFP-patients with positive VZV T cell status (n = 45) were compared depending on the PFP-score. Expression of C CTLA-4 (n = 39), D CD27 (n = 34), and E Ki67-positivity (n = 34) of VZV-specific T cells is shown in patients with different PFP-scores. F Dot plots of a 79-year-old PFP-patient with VZV-reactivation show characteristic expression of CTLA-4 (upper) and Ki67 (lower) on (IFNγ +) CD4 T cells after in vitro stimulation with VZV-antigen. G CTLA-4 and Ki67-expression of VZV-specific CD4 T cells was correlated among all VZV T cell-positive samples of PFP-patients where both markers were available (n = 34). To ensure robust statistics, analysis in C, D, E and G was restricted to samples with at least 20 antigen-specific CD4 T cells. Dotted lines in C, E and G represent cut-offs (3579 MFI for CTLA-4 [22], and 8% for %Ki67-positive) which discriminated best between VZV-associated PFPs and non VZV-associated PFPs. Patients with dark red and light red symbols refer to patients with high CTLA-4 expression levels on VZV-specific T cells and/or high percentage of Ki67-positive VZV-specific T cells. Among them, dark red symbols refer to patients with VZV-related skin disease (3 patients with zoster oticus, 1 patient with Ramsay Hunt zoster and 1 patient with concomitant cervical (C2) zoster efflorescence). One patient (light red) did not have sufficient blood for CD27- and Ki67-staining. Numbers in panel F indicate CTLA-4-MFI and percentage of Ki67-positive of VZV-reactive CD4 T cells. CTLA-4, cytotoxic T-lymphocyte antigen 4; IFN, interferon; MFI, median fluorescence intensity; PFP, peripheral facial palsy; VZV, varicella-zoster virus