<qa>  What is the CART22 trafficking assessment?All patients will have blood tests to assess CART22 safety, engraftment and persistence at regular intervals throughout the study Visit Evaluation Schedule in Appendix 1. Circulating CART22 T cells subsets will be assessed at various times after infusion. CART22 trafficking will be assessed in bone marrow aspirates, and other tissues, if available. Follow up is planned at a minimum of weekly for 4 weeks, monthly for 6 months, then patients will be followed quarterly for the remainder of the year to obtain a medical history, undergo a physical examination, and blood tests. Additional samples collections and assessments between schedule visits after CART22 cell infusion will be performed as clinically indicated. 