Rejection and infection are primary causes of morbidity and mortality in solid organ transplant recipients. Current clinical practice relies on immunosuppressive drug levels measured in plasma to reflect the peripheral immune response in solid organ transplant recipients. Direct measurement of the number and functions of the immune cells themselves using multi-parameter flow cytometry may enable individualized immunosuppression management for organ transplant recipients. Multi-parameter flow cytometry will be used to compare levels and functional capabilities of multiple lymphocyte subsets between cohorts of patients receiving depletion induction and those receiving a non-depletion regimen. The activation state, cytotoxic potential and the functional capabilities of these cells will be examined within patients over the first six months post transplant.