Immunology

The investigators want to study if lower doses of chemotherapy will help babies with SCID to achieve good immunity with less short and long-term risks of complications after transplantation. This trial identifies babies with types of immune deficiencies that are most likely to succeed with this approach and offers them transplant early in life before they get severe infections or later if their infections are under control. It includes only patients receiving unrelated or mismatched related donor transplants.

The study will test if patients receiving transplant using either a low dose busulfan or a medium dose busulfan will have immune recovery of both T and B cells, measured by the ability to respond to immunizations after transplant. The exact regimen depends on the subtype of SCID the patient has. Donors used for transplant must be unrelated or half-matched related (haploidentical) donors, and peripheral blood stem cells must be used. To minimize the chance of graft-versus-host disease (GVHD), the stem cells will have most, but not all, of the T cells removed, using a newer, experimental approach of a well-established technology. Once the stem cell transplant is completed, patients will be followed for 3 years. Approximately 9-18 months after the transplant, vaccinations will be administered, and a blood test measuring whether your child's body has responded to the vaccine will be collected.

Cystic Fibrosis Related Diabetes has been identified by the CF community as one of the top ten priorities for CF research. In CF clinical decline due to dysglycemia begins early, prior to diagnosis of diabetes and increases mortality from pulmonary disease. There is presently no way to determine who, of those with dysglycemia, will experience clinical compromise. However, the CF Center in Milan has found that measurable age- and sex-dependent variables on oral glucose tolerance testing (OGTT) predict β-cell failure-the primary driver of decline in CF. the investigators propose a multi-center trial to develop nomograms of age and sex dependent reference values for OGTT-derived measures including glucose, insulin, c-peptide, and the resultant OGTT-derived estimates of β-cell function, β cell sensitivity to glucose, and oral glucose insulin sensitivity (OGIS) and to determine correlation of these with clinical status (FEV-1, BMI z score, number of pulmonary exacerbations over the past 12 months). In a subset of the cohort the investigators will perform additional studies to determine possible mechanisms driving abnormal β cell function, including the role of lean body mass (as measured by DXA), impact of incretin (GLP-1, GIP) and islet hormones (glucagon, pancreatic polypeptide) on β cell function and the relationship of reactive hypoglycemia and catecholamine responses to β cell function, as well as the relationship of β cell sensitivity to glucose as determined by our model to abnormalities in blood glucose found in a period of free living after the study (determined by continuous glucose monitoring measures (Peak glucose, time spent \>200 mg/dl, standard deviation). the investigators will also develop a biobank of stored samples to allow expansion to the full cohort if warranted and to enable future studies of dysglycemia and diabetes in CF. the investigator's eventual goal is utilization of the nomograms to determine the minimum number of measures to accurately predict risk for clinical decline from dysglycemia in CF.