THE RELATIONSHIP BETWEEN BCL-2 EXPRESSION AND RESPONSE TO CHEMOTHERAPY IN ACUTE-LEUKEMIA

Immunocytochemistry was used to assess bcl-2 expression in blasts obta ined from the bone marrow of 28 patients with acute lymphoblastic leuk aemia (ALL) (16 children and six adults at presentation and three chil dren and three adults on relapse) and 20 with acute myeloid leukaemia (AML) (19 adults and one child, 13 with de novo AML, 11 at presentatio n and two on relapse, and seven secondary to myelodysplasia or chronic myeloid leukaemia). Slides were examined both for the percentage of p ositive cells and for the intensity of staining using a five-point sca le. There was a statistically significant increase in both the percent age of positive cells seen (P < 0.002) and the intensity of staining ( P < 0.01) between samples obtained at relapse and those at presentatio n in ALL. There was a significantly greater intensity of staining in c ells from patients with ALL (P < 0.05) and AML (P < 0.05) who failed t o achieve remission after chemotherapy than in those who responded. Th e intensity of staining in cases of secondary AML was lower than that in de novo disease (P < 0.01). These results suggest that expression o f bcl-2 may be an important prognostic feature in both de novo AML and in ALL, but not in secondary AML.