P29 Reduced expression of Tim-3 renders Th1 and Th17 effector cells less amenable to T-reg control in autoimmune hepatitis

IntroductionIn autoimmune hepatitis (AIH), CD4 effector immune responses are permitted by defective CD4+CD25+ regulatory T-cells (T-regs). In murine studies apoptosis of Th1 effector cells is mediated by binding of T-cell-immunoglobulin-and-mucin-domain3 (Tim-3) on their surface to Galectin-9 (Gal9) expressed by T-regs. In AIH, Tim-3 is down-modulated on CD4 effector cells.AimTo test the frequency of Tim-3+ cells within the Th1, Th2 and Th17 subsets and to evaluate whether Tim-3 expression by CD4 effectors affects their responsiveness to T-reg control.Method39 ANA/SMA+ patients (23 females; median age: 13.9 years) and 16 healthy subjects (HS, 12 females; median age: 29.5 years) were studied. Cell phenotype was determined by cytofluorimetry using monoclonal antibodies to CD4, CD25 and TIM3. The frequency of cells positive for T-bet, GATA3 and RORC, transcription factors defining Th1, Th2 and Th17 cell subsets, was determined by intracellular staining. Proliferation of CD25−, CD25−Tim-3+ and CD25−Tim-3− target cells was assessed by 3H-thymidine incorporation after 5-day co-culture with T-regs.ResultsThe frequency of Tim-3+ cells within the Th1 and the Th17 subsets was lower in AIH than in HS (Th1: 5.1±0.7 vs 13.6±1.7, p