RESISTANCE FACTORS AND PROLIFERATIVE ACTIVITY IN CHILDHOOD ACUTE NONLYMPHOBLASTIC LEUKEMIA

Thirty-four children with newly diagnosed acute nonlymphoblastic leuke mia were analysed for the expression of P-glycoprotein (P-170), glutat hione S-transferase-pi, (GST-pi) topoisomerase II (Topo II) and the pr oliferation antigen Ki-67 by the streptavidin-biotin-peroxidase method . Overexpression of P-170 was present in 26 cases (76%) and GST-pi ove rexpression was seen in 11 patients (32%). Down regulation of Topo II was found in 16 patients (47%) and Ki-67 positive cells (>5%) were det ectable in 9 patients (26%). The remission rate was not influenced by P-170 or GST-pi expression, whereas patients with down regulation of T opo II or low Ki-67 expression had lower remission rates. The data wer e not significant. The probability of continuous first remission (CR) was lower in patients with P-170 expression (p=0.09). A significantly lower probability of CR was also seen in patients with low proliferati ve activity (p=0.03, log-rank test). The expression of the resistance proteins and the proliferative activity were found to be independent o f the clinical parameters age, sex, FAB-type, and initial white blood cell count.