Originally the study included 11 groups as listed; however, at present only groups 1,4, and 8 remain active. Whereas the initial study duration was 6 years, this was extended to 11 years in order to follow over more extended time a B cell signature identified for tolerant kidney subjects and how this signature may change. (Refer to publications section: Newell, Kirk et al, J Clin Invest. 2010).