The objective of this study is to assess the efficacy of hydroxychloroquine (HCQ) when
combined with Mesalamine in reducing clinical and histologic disease activity in patients who
have active mild to severe Ulcerative Colitis (UC) and also to assess the immunological
effects of hydroxychloroquine in this population. These outcomes will be evaluated both
clinically and experimentally. In vitro, flow cytometry will be employed to measure the
expression of CTLA-4 on activated CD4+CD25+CD127- Tregs from patients prior to treatment with
HCQ, and then at the end of a 4 month follow up period. Suppression assays will be used to
determine the functional capacity of the patient derived Tregs. Clinically, patients will be
monitored for remission as defined by reduction in patient reported stool frequency and
rectal bleeding (mayo sub-score 0 or 1) and endoscopically, by improvement in mucosal
appearance (mayo sub-score 0 or 1), all objective measures in the mayo score.