Inclusion Criteria: - Healthy participant, defined as having no clinically significant active or ongoing medical condition, physical examination abnormality, abnormal ECG finding, with no current use of tobacco - A negative QuantiFERON-TB Gold® test result at screening or documentation of a negative result within 3 months of the screening visit and a weight ≥ 50 kg and BMI between 18.0 and 32.0 kg/m2 inclusive at screening. - Participants must not be current users (within 6 months before screening) of tobacco or tobacco- or nicotine-containing products; they must also be willing to refrain from using any of these products during their participation in the study. - Men who are sexually active with women of childbearing potential (WOCBP) must agree to follow instructions for method(s) of contraception (APPENDIX 4) for the duration of treatment with BMS-986256 or MMF, plus 5 half-lives of BMS-986256 (19 days) plus an additional 90 days (duration of sperm turnover) for a total of 109 days post treatment. In addition, participants must be willing to refrain from sperm donation during this time. Exclusion Criteria: - Any significant acute or chronic medical illness or condition, in the opinion of the investigator in addition to prior exposure to BMS-986256 - Major surgery within 4 weeks before study treatment administration, drug abuse or drug addiction. - Participants who have smoked or used smoking cessation or other nicotine-containing products within 6 months before the first dose of study drug. - History or presence of malignancy including hematological malignancies. However,participants with a history of basal cell or squamous cell carcinoma of the skin that has been completely and successfully treated with no evidence of recurrence may not be excluded, at the discretion of the investigator.