RESUMEN
BACKGROUND: Several methods have been used to evaluate the engraftment and to monitor residual disease after bone marrow transplantation (BMT). Among them, karyotyping have been useful in gauging engraftment following opposite sex BMT. More recently, fluorescence in situ hybridization (FISH) has also been applied to determine engraftment and residual status. In order to establish the utility of this method in clinical practice, we have evaluated the data from FISH and several methods. METHODS: We performed FISH using chromosome X alpha-satellite probe (Oncor , USA) on twenty eight peripheral blood and nine bone marrow nuclear cells from eleven patients who underwent sex mis-matched transplant and from a patient who had a loss of X chromosome. RESULTS: In nine patients with well engrafted BMT, signals of host cells showed less than 5% in all patients, evaluated 21-210 days post-transplant. Mixed chimerism was detected in six patients; transiently in early post-transplant period in four, in a patient with engraftment failure, and in a patient with relapse, respectively. CONCLUSION: FISH using X probe is a rapid, quantitative and sensitive 'interphase cytogenetic method' for the evaluation of engraftment and monitoring of residual disease following sex mis-matched BMT or BMT in a patient with a loss of X chromosome; It is especially useful in early post-transplant period when ony a few cells are available during severe cytopenia.