Kinetic Analysis of Immune Cells in Blood and Chronic Graft-Versus-Host Disease-Affected Tissues after Allogeneic Hematopoietic Cell Transplantation

Inclusion Criteria

• * BOTH COHORTS: ** Documented written informed consent of the participant and/or parent/guardian. *** Assent from pediatric participants will be documented per institutional policies and practice. ** Patients who have received allogeneic hematopoietic cell transplant (HCT) regardless of donor type, condition regimen, or GVHD prophylaxis. ** Age: ≥ 18 years or ≥ 7 years if 30 kg and above ** Willingness to: *** Provide blood sample(s), stool, saliva, and buccal mucosa, *** If applicable: Permit medical record/ clinical laboratory result review * COHORT 1: ** Patients who have received allogeneic hematopoietic cell transplant (HCT) regardless of donor type, condition regimen, or GVHD prophylaxis. * COHORT 2: ** Patients diagnosed with cGVHD at any time-point after allogeneic HCT regardless of donor type, condition regimen, or GVHD prophylaxis.

Exclusion Criteria

• * Women of childbearing potential: Pregnant/nursing * Individuals with impaired decision-making capacity * An employee who is under the direct/ indirect supervision of the PI/ a co-investigator/ the study manager * A direct study team member