Apoptotic fraction in childhood ALL assessed by DNA in situ labelling is ploidy independent

Apoptotic cell fraction and presence or degree of aneuploidy may both affect treatment outcome in childhood acute lymphoblastic leukaemia (ALL), which is largely defined by drug resistance. Independence of the variables is at present not established. Until the development of in situ labelling of cells committed to the apoptotic pathway, the fraction of cells in apoptosis could not be determined objectively.

To determine the relationship between apoptotic cell fraction and karyotype in childhood ALL using in situ labelling.

1.3.1. Study Groups and Samples. Diagnostic, pretreatment bone marrow trephine and aspirate samples of 24 consecutive, unselected cases of childhood ALL were included in the study: Normal karyotype (n = 11, 5M,6F), high hyperdiploid aneuploidy (DNA index > 1.5, n = 7, 1M,6F), complex karyotypic anomalies (n = 6, 5M,1F). 1.3.2. Apoptotic Cell Labelling. In situ labelling of the 3'-OH ends of the apoptosis specific DNA (Klenow) fragment (Frag-EL, CalBiochem, USA). 1.3.3. Quantitation. Apoptotic cell fraction was established using 10 systematically random fields of > 20 nuclei. Results were tabled per group. After calculations of means, differences between groups were assessed using t-test.

Apoptotic cell fraction, ranging from < 1 to 95%, did not differ statistically significant between the three study groups.

Apoptotic cell fraction in childhood leukaemia is independent of ploidy status and euploid karyotypic anomalies.