Chimerism in allogeneic mini-transplantation

The need of quantitation of chimerism is increasing as mini-transplantation has been on trial and they are possibly become the mixed chimeras. FISH method using XY chromosome as a marker is effective in heterosexual transplantation, And STR-PCR method is effective in homosexual transplantation. There is wide range in strength of pre-conditioning in Mini-transplantation; almost all stronger pre-conditioning with fludarabine end up in completely donor-type, and the pre-conditioning with ATG, TBL, L-PAM, M-Pred, 40% became mixed chimera but they all became completely donor type with DLI. There is a report that there are less GVHD with mixed chimera. To decide which pre-conditioning to use, we need to examine the rate of the relapse.