Polymorphism and Auto-reactive B and T Cells Subsets in Adult's Immune Thrombocytopenia (ITP) (Poly-ITP)

Fc Gamma RIIIA V/F158 Polymorphism and Auto-reactive B and T Cells Subsets in Adult's Immune Thrombocytopenia (ITP) and Correlations With Treatment

Aims of the study : 1) To determine whether the presence of the V158 allele of Fc gammaRIIIA gene is associated with a better outcome of Immune Thrombocytopenia (ITP) in adults and especially with a higher response-rate to rituximab. 2) To analyze the impact of therapy and especially rituximab on some B and T cells autoreactive subsets in the peripheral blood. Patients and Methods : Inclusion criteria : age ≥ 18 years, primary ITP defined according to the recent consensual criteria (Rodeghiero F et al. Blood 2009), active ITP defined as an ITP with a platelet count < 50 x 109/L requiring treatment, informed consent. Main exclusion criteria : secondary ITP. Blood samples (serum, plasma, DNA) will be collected in every patient at time of inclusion (pre-treatment) and then sequentially at 3, 6 and 12 months after inclusion in patients treated with rituximab or during the remission phase for other treatments for immunological studies. When a marrow analysis is indicated, some marrow specimens will also be collected and studied and if a patient will have to undergo a splenectomy as a standard of care, some spleen specimens will also be collected. Fc gamma RIIIA V/F158 polymorphism will be assessed by means of an allele-specific PCR. The sequential analysis of anti-platelets (anti-GpIIbIIIa) antibodies producing B cells will be performed by means of flow cytometry and ELISPOT analysis. T cells subsets will be harvested in presence of GpIIbIIIa immunodominant peptides and and cytokines expression will be measured on supernatants on days 2 and 11 in vitro by using Luminex technology in order to characterize and distinguish TH1, TH2, TH17, TFH and Tregs subsets. The primary outcome will be the overall response rate 1 year after inclusion defined by a platelet count > 30 x 109/L with at least a two-fold increase of the initial (pre-treatment) count. For the patients treated with rituximab as a standard of care, based on the overall expected response-rate (40-50%) and based on preliminary data on FcgammaRIIIA V/F158 distribution, the inclusion of 85 patients should be sufficient to show an association of the V158 allele and the response (b risk 20% and a 5%). Responders and non responders will be compared by non parametrical tests, a multivariate analysis will be than performed using a logistic regression model. The immunological data B and T cells subsets) obtained in both the responders and the non responders will be compared over time (To, M3, M6 and M12) by non parametrical matched tests.

Immune thrombocytopenia, Fc gamma RIIIA V/F158 polymorphism, Rituximab, autoreactive B and T cells, ITP

The overall response rate to rituximab defined by a platelet count > 30 x 109/L with at least a two-fold increase of the initial (pre-treatment) count

Inclusion Criteria: Age ≥ 18 years Primary ITP as defined by the internation consensus on terminology (Rodeghiero et al. Blood 2009) regardless the phase of the disease (newly-diagnosed, persistent of chronic ITP) active ITP defined by a platelet count < 50 x 109/L at time of inclusion with indication for treatment Informed consent Exclusion Criteria: Secondary ITP