National identity remains one of the most potent forces in global politics, yet surprisingly little is known about processes of national identity formation and change. This article argues that national identity preferences are susceptible to fluctuations in group status and distance but constrained by conflict experience and socialization. Integrating research on conflict socialization with social identity theory, we hypothesize that growing up during violent intergroup conflict socializes individuals into identities and attitudes which are durable to significant changes. Conversely, the identity preferences of those who grow up during relative peace are more malleable and likely to change due to significant events which affect perception of group identities. Exploiting the unique political context in Northern Ireland, where individuals can legally choose to identify as Irish, British, or both, we use a diff-in-diff approach to estimate national identity preferences of individuals before and after the EU referendum. The results show that 20% of Protestants who did not experience conflict shifted from British towards Irish identity after the referendum. However, for those who experienced violent intergroup conflict, there is a ‘durable distance’ between groups which constrains identity change irrespective of fluctuations in status. The results have important implications for our understanding of national identity, particularly in post-conflict societies.

In recent years, a record number of people have been forcibly displaced or migrated due to conflict. Whilst established political science research suggests that displaced communities are an added risk factor for conflict due to their support for extreme co-ethnic political parties and movements, this has been challenged by recent research which shows that migrants can be a moderating force. We offer a potential reconciliation of these divergent findings by distinguishing between first- and second-generation migrants. Due to their relative lack of conflict exposure, second-generation migrants will have significantly less support for co-ethnic political parties than first-generation migrants and those who remain. We test our argument using granular survey data comparing Kurds who migrated out of the conflict zone in Turkey with those who remained. The results support our theoretical framework and have important implications for our understanding of migrant attitudes and the long-term effects of conflict exposure.

Background:Effective treatment of Rheumatoid arthritis (RA) patients is achievable within a short window of opportunity following diagnosis. T-cells are early drivers of synovial inflammation of RA, therefore, identification of pathogenic T-cell subsets at the synovial tissue of pre-RA, arthralgia subjects, would greatly improve our understanding of disease pathogenesis. Comparative analysis of healthy control, arthralgia subject and RA-patient derived synovial tissue T-cell responses will lead to the identification of pathogenic as well as protective cytokine milieu, thus enabling the identification of early therapeutic targets to help steer the immune response towards resolution.Objectives:Characterization of T-cell polyfunctionality in the periphery and synovial tissue of ’at-risk; subjects (Arthralgia) RA-patients and healthy controls (HC).Identification of specific, pathogenic, synovial tissue T-cell subsets.Methods:Synovial biopsies from RA, AR and HC were obtained by arthroscopic surgery followed by RNAseq analysis (Guo et al., PLoS One, 2018). Single cell synovial tissue cell suspensions from RA, AR and HC and paired PBMC were stimulated in vitro and polyfunctional synovial T-cell subsets examined by flow cytometric analysis, SPICE visualization and FlowSom clustering. Flow-Imaging, was utilised to confirm specific T-cell cluster identification. Fluorescent Lifetime Imaging Microscopy (FLIM) was used to visualise metabolic status of specific T-cell populations.Results:T-cell associated pro-inflammatory gene pathways were increased in RNAseq analysis of RA-patient and arthralgia subject compared to HC synovial tissue biopsies. Flow cytometric analysis of pro-inflammatory cytokine (TNF-α, IFN-γ, IL-2, GM-CSF, IL-17A, IL-22) production and SPICE analysis of ex vivo stimulated T-cells revealed marked polyfunctionality of arthralgia subject synovial T-cells, thus providing evidence for a dysregulated synovial T-cell response that pre-dates clinical onset of disease. Importantly, HC synovial tissue harbours a small, albeit surprisingly polyfunctional, CD4 T-cell population characterised by significantly increased IL-4 and GM-CSF cytokine production compared to arthralgia subject (P<0.001 and P=0.01) and RA-patient (P<0.001 and P=0.004) synovial tissue. However, not all polyfunctional T-cells are equal in their pathogenic potential. Therefore, in order to identify highly pathogenic synovial T-cells, cluster analysis of flow cytometric data using the unsupervised algorithm FlowSom was performed and led to the identification of specific T-cell clusters with unique polyfunctionality characteristics. Specifically a cluster of CD4+CD8+ double positive (DP) T-cells with high polyfunctionality scores was identified. Hybrid flow cytometry and imaging technique confirmed the co-expression of CD4 and CD8 by a synovial T-cell population. DP T-cells are enriched in RA-patient synovial fluid and synovial tissue and arthralgia subject synovial tissue, but are absent from HC synovial tissue. Importantly, DP T-cell synovial accumulation strongly (P=0.002) correlates with DAS28(CRP) of RA-patients. Initial studies utilising the novel, non-invasive FLIM technique for visualisation of cellular NAD, revealed that DP T-cells have a metabolic profile indicative of activated memory T-cells.Conclusion:These data highlight a key early loss of balance between protective and pathogenic synovial T-cell polyfunctionality and the emergence of specific, highly polyfunctional and pathogenic T-cell clusters in RA.Figure 1.Identification of highly polyfunctional and pro-inflammatory synovial DP T-cells. A. Cluster analysis of RA-patient synovial tissue T-cells (asterisks indicate DP T-cell clusters). B. Flow imaging of CD4+, CD8+ and DP synovial T-cells. C. SPICE flow cytometric data visualization of DP arthralgia subject and RA-patient synovial T-cells. D. Correlation between the frequency of RA-patient synovial DP T-cells and disease severity.Disclosure of Interests:Achilleas Floudas: None declared, Nuno Neto: None declared, Mary Canavan: None declared, Trudy McGarry Employee of: Novartis, Vinod Krishna Employee of: Janssen, Sunil Nagpal Employee of: Janssen, GSK, Michael Monaghan: None declared, Douglas Veale Speakers bureau: Abbvie, Janssen, Novartis, MSD, Pfizer, UCB, Consultant of: Abbvie, Janssen, Novartis, MSD, Pfizer, UCB, Grant/research support from: Janssen, Abbvie, Pfizer, UCB, Ursula Fearon Speakers bureau: Abbvie, Grant/research support from: Janssen, Abbvie, Pfizer, UCB.