Automated counting of in situ hybridization dots in interphase cells of leukemia samples

Twenty-seven samples (cell cultures prepared for routine cytogenetics) of leukemia patients with known cytogenetic abnormalities were stained by in situ hybridization for interphase cytogenetics with centromere specific probes for chromosome Nos 4, 6, 7, 8, 9, 12, 17, 18, X and Y. The number of hybridization domains per nucleus was quantified using a semi-automated system developed in our laboratory. Results of this automated counting procedure (with and without verification of the counting results by the operator) were compared with conventional cytogenetic data and with visual scoring of the number of hybridization dots. The findings show that the system is capable of analysing 1000 cell nuclei in less than 30 min, including the necessary verification of the results by the operator. Automated counting and visual scoring were in good agreement. Conventional cytogenetics and interphase cytogenetics agreed in only 50% of the cases, confirming other studies showing that conventional cytogenetic results are not always representative for the majority of the cell population.