AB0165 In Depth Immunophenotypic Analysis In Juvenile Idiopathic Arthritis (JIA): A Crossectional Study

Background The potential of expanded flow cytometric analysis of PBLs has not been yet been fully exploited to study JIA heterogeneity neither to monitor JIA patients9 on biological treatments Objectives To analyze in depth lymphocyte subpopulations in treated JIA patients stratified by age and gender. Methods One hundred one patients, 69 children and 32 adult fulfilling JIA (ILAR) criteria attending HUVH rheumatology clinic were included. All patients were treated with either MTX, anti-TNFα, or a combination of both. Controls were sex/age matched volunteers either healthy or attending the clinics of HUVH for non inflammatory conditions (59 controls, 29 paediatric and 30 adult). Extended immunophenotype following FITMaN protocol that discerns 57 peripheral blood lymphocyte (PBL) subpopulations was applied. Bonferrroni9s correction indicated that the cut off for significance was p Results Changes common to each group of patients irrespective of treatment are as follows: paediatric patients showed lower percentage of CD8 effector cells (CD45RA+CCR7-) when compared to controls (10.53±5.71 vs 16.92±5.71). Percentage of total CD4 cells was higher on JIA children than in controls (42.21±7.40 vs 36.04±5.22). No differences were found on percentages nor in absolute number of Th1 (CXCR3+CCR6-), Th2 (CXCR3-CCR6-), or Th17 (CXCR3-CCR6-) CD4 cells. Interestingly all Th subpopulations showed decreased expression of HLA-DR in JIA children when compared with controls (6.06±3.08 vs 10.49±5.02; 0.81±0.51 vs 1.48±0.64; 8.57±3.81 vs 12.6±4.95; respectively). JIA adults presented no significant differences in T cells subpopulations compared to adult controls, but showed higher percentage of CD21- switch-memory B cells (IgD-IgM-CD27-) than controls (10.82±5.33 vs 4.29±4.33). In a second analysis of the JIA patients few differences were observed according to the administered therapy. Paediatric patients treated with MTX (n=27) showed a lower proportion of the effector memory (CD45RA-CCR7-) cells both CD4+ and CD8+, when compared to controls, anti-TNF, and anti-TNF plus MTX groups (20.01±7.76 vs 27.64±9.27; 20.01±7.76 vs 27.84±4.27; 20.01±7.76 vs 27.07±10.05; for CD4s and 26.42±7.23 vs 37.10±12.38; 26.42±7.23 vs 42.08±11.59; 26.42±7.23 vs 37.27±12.54 for CD8s, respectively). Percentage of CD25+ lymphocytes was higher in the anti-TNF plus MTX group. The Th1–17 (CCR6+CXCR3+) CD4 cell subpopulation was significantly increased in anti-TNF and anti-TNFα plus MTX groups compared with controls and MTX (10.45±3.14 vs 6.38±3.89; 10.45±3.14 vs 4.78±2.56 and 9.43±4.63 vs 6.38±3.89; 9.43±4.63 vs 4.78±2.56, respectively). Adult patients treated with anti-TNFα+MTX and MTX presented higher levels of CD21- naive B cells compared to HC and to anti-TNF groups (4.86±3.24 vs 2.32±1.69; 4.86±3.24 vs 2.95±1.94 and 5.38±1.54 vs 2.32±1.69; 5.38±1.54 vs 2.95±1.94). Conclusions In depth phenotypic analysis of PBL in JIA showed alterations in cell subpopulations that seem dependent on age group. Our data also suggests that detailed in depth phenotypic analysis can be a valuable tool for monitoring and comparing JIA treatments. Disclosure of Interest None declared