Both adult and pediatric patients who undergo allogeneic HSCT during the study period will be identified. Data will be collected from the computerized database as detailed below. Prior to conditioning and HSCT a baseline stool sample will be obtained and evaluated for bacterial content. Subsequent surveillance stool samples will be obtained on a weekly basis and at the onset and recovery of iGVHD and evaluated. if endoscopy/colonoscopy is performed for evaluation for iGVHD, intestinal tissue will be obtained and evaluated for the presence and quantification of specific cytokines (e.g. iL-17 and iL-23) and also transcription and protein levels of TLRs.
- Pediatric patients who undergo allogeneic HSCT at Children's Medical Center Dallas.
-Pediatric patients who undergo allogeneic HSCT at Cincinnati Children's Hospital Medical Center.