Purpose: To evaluate in a sequential fashion the activity of the leukocyte alkaline phosphatase (LAP) in the chronic phase and the blastic crisis of chronic myelogenous leukaemia (CML).
Material and methods: This study is comprised of 43 patients diagnosed of CML according to standard criteria. The initial LAP scores were compared with those recorded in the blastic crisis, using cytochemical methods. The statistical analysis was performed with Student's test and chi-square.
Results: The LAP activity at diagnosis was low in 40 of the 43 cases (93%), the score being 0 in 20 instances. In the blastic crisis low scores were found in 27 patients (63%), while LAP activity appeared normal or increased in 16 others (37%). When the LAP scores of the two phases of the disease were compared the differences were found statistically significant (p less than 0.0001 and p less than 0.0007, respectively).
Conclusions: These results confirm that the onset of the blastic crisis of CML is often accompanied by an increase of the LAP activity, although this last persists low in the majority of the patients.