Mixed chimerism after sex-mismatched allogeneic BMT: evaluation of two molecular techniques.

ABSTRACT

Two different molecular techniques were used to monitor chimerism following 17 non-T cell-depleted BMTs from female donors to male recipients pHY10, a Y chromosome-specific probe (Southern or slot blots), and a set of primers for Y chromosome sequence-specific amplification by the polymerase chain reaction (PCR). On Southern blots, male DNA was detectable at a level less than 1% of 10 micrograms DNA while cross-reactivity with autosomal sequences was avoided. On slot blots, male DNA was reliably detectable at levels less than 0.5%, even in small sample (0.5 microgram DNA). With the PCR technique, male DNA was detectable at levels of 110(6) to 110(7) of 0.5 microgram DNA. Slot blot and PCR results were concordant in 19 of 23 samples. Both techniques demonstrated a constant small mixed chimerism during the first year after BMT and in four of nine patients, this chimerism persisted even longer (up to 29 months after BMT).