This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to measure and compare levels of TGF¿1 in cystic fibrosis patients and healthy control subjects. TGF¿1 has been implicated as a potential immune modulator in CF patients with certain genotypes (results from GCRC #1774) and has been shown to alter wound repair. This study is being done to further characterize what differences (if any) exist between circulating TGF¿1 levels in CF patients with two different genotypes and in addition, to describe TGF¿1 levels in normal volunteers. The initial blood samples used to determine genotype will come from samples already collected under GCRC #1774 ?Gene Modifier Study? and the normal volunteer samples will be requested from the Environmental Polymorphisms Registry (GCRC #2140). Both groups of subjects will then be asked to come to either the GCRC or the CF clinic to have a single 35 ml blood sample drawn to measure TGF¿1 levels. A clearer understanding of the potential role of TGF¿1 may lead to further studies as a potential therapeutic target for CF.