The effect of isolated leukaemic blasts on platelet aggregation

The effect of blastic cells isolated by Böyum's method from the blood of 20 nontreated patients with acute myelogenous leukaemia on normal platelet aggregation has been studied. The isolated blasts in concentration of 2,000/microliter and higher, inhibit normal platelet aggregation induced by ADP or collagen, but have no influence on aggregation initiated by epinephrine. This effect is unaffected by the presence of metabolic poisons or by the disruption of the blastic cell membrane. Our results seem to exclude interference of blastic cells with platelet prostaglandin biosynthesis. In patients with acute leukaemia and an increased leukocyte count the preparation of platelet suspension free of blastic cells is not possible, even by the albumin gradient method or by gel filtration. The leukaemic blast content in platelet-rich suspensions may account for the variations in the aggregation behaviour which are found in these patients. The influence of blastic cells may be an important factor in the bleeding tendency in myelogenous leukaemia