Contributions
Abstract: P754
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - Immunology
Neuropathological and immunological studies suggest that neuroinflammation in MS might be caused by an immunopathological response toward a persistent, intracerebral EBV infection. CD8+ T cells dominate the immune infiltrate in the MS brain and several studies showed enrichment of EBV-specific CD8+ T cells in patients' CSF. However, demonstration of EBV-specific CD8+ T cells in situ is still missing.
The aim of this study was to find out whether EBV-specific CD8+ T cells could be visualized in MS brain sections using the pentamer technique.
Post-mortem snap frozen brain tissue blocks from patients with progressive MS were obtained from the UK MS Tissue Bank. Thirty-six tissue blocks from 34 MS patients carrying the appropriate MHC class I alleles were screened for good tissue preservation and presence of florid immune infiltrates. Brain samples from 12 MS cases were included in the pentamer binding study. Brain sections were stained with HLA class I-matched pentamers (ProImmune) to identify CD8+ T cells specific for immunogenic peptides from EBV latent and lytic proteins, proteins of control viruses (HCMV, influenza A) and myelin basic protein (MBP). The localization and frequency of pentamer+ cells in the total infiltrating CD8+ T cell population was assessed.
EBV-specific CD8+ T cells were detected in brain sections from 11/12 MS cases and binding of EBV pentamers to CD8+ T cells was confirmed by double pentamer/CD8 immunostainings. Cells binding EBV pentamers were present in the inflamed meninges and perivascular spaces of inflamed blood vessels in active white matter lesions. The fraction of CD8+ T cells specific for individual EBV protein-derived peptides ranged between 0.1 and 4.5%; CD8+ T cells specific for EBV proteins associated with latency III/growth program and with immediate early (BZLF1) and early (BMLF1) phases of the lytic cycle were the most frequent. CMV-specific CD8+ T cells were detected at a very low frequency (< 0.1%) in brain samples from 4 of 12 MS cases; no influenza A- and MBP-specific T cells were found. No pentamer+ cells were observed when sections were stained with HLA class I-mismatched pentamers.
These results suggest selective migration of EBV-specific CD8+ T cells in the MS brain. Together with neuropathological evidence that EBV infection is dysregulated in the MS brain, these data support the concept that a CD8+ T cell-mediated immunopathological response toward EBV might sustain chronic neuroinflammation in MS.
Disclosure: This study is funded by Fondazione Italiana Sclerosi Multipla (to BS) and Italian Ministry of Health (to FA).
The authors have nothing to disclose.
Abstract: P754
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - Immunology
Neuropathological and immunological studies suggest that neuroinflammation in MS might be caused by an immunopathological response toward a persistent, intracerebral EBV infection. CD8+ T cells dominate the immune infiltrate in the MS brain and several studies showed enrichment of EBV-specific CD8+ T cells in patients' CSF. However, demonstration of EBV-specific CD8+ T cells in situ is still missing.
The aim of this study was to find out whether EBV-specific CD8+ T cells could be visualized in MS brain sections using the pentamer technique.
Post-mortem snap frozen brain tissue blocks from patients with progressive MS were obtained from the UK MS Tissue Bank. Thirty-six tissue blocks from 34 MS patients carrying the appropriate MHC class I alleles were screened for good tissue preservation and presence of florid immune infiltrates. Brain samples from 12 MS cases were included in the pentamer binding study. Brain sections were stained with HLA class I-matched pentamers (ProImmune) to identify CD8+ T cells specific for immunogenic peptides from EBV latent and lytic proteins, proteins of control viruses (HCMV, influenza A) and myelin basic protein (MBP). The localization and frequency of pentamer+ cells in the total infiltrating CD8+ T cell population was assessed.
EBV-specific CD8+ T cells were detected in brain sections from 11/12 MS cases and binding of EBV pentamers to CD8+ T cells was confirmed by double pentamer/CD8 immunostainings. Cells binding EBV pentamers were present in the inflamed meninges and perivascular spaces of inflamed blood vessels in active white matter lesions. The fraction of CD8+ T cells specific for individual EBV protein-derived peptides ranged between 0.1 and 4.5%; CD8+ T cells specific for EBV proteins associated with latency III/growth program and with immediate early (BZLF1) and early (BMLF1) phases of the lytic cycle were the most frequent. CMV-specific CD8+ T cells were detected at a very low frequency (< 0.1%) in brain samples from 4 of 12 MS cases; no influenza A- and MBP-specific T cells were found. No pentamer+ cells were observed when sections were stained with HLA class I-mismatched pentamers.
These results suggest selective migration of EBV-specific CD8+ T cells in the MS brain. Together with neuropathological evidence that EBV infection is dysregulated in the MS brain, these data support the concept that a CD8+ T cell-mediated immunopathological response toward EBV might sustain chronic neuroinflammation in MS.
Disclosure: This study is funded by Fondazione Italiana Sclerosi Multipla (to BS) and Italian Ministry of Health (to FA).
The authors have nothing to disclose.