In view of prior reports of platelet activation in the sickling disorders, platelet aggregation, malondialdehyde (MDA) production following stimulation with N-ethylmaleimide, and/or production time (survival) measurements were examined in 44 children with homozygous sickle cell disease. Aggregation in response to epinephrine, collagen, and adenosine diphosphate was similar to or only slightly less than in normal black controls, rendering high unlikely the circulation of a sizable population of refractory or 'exhausted' platelets. The platelets from the normal blacks aggregated less in response to epinephrine than those from white control subjects. MDA generation in sickle cell platelets was not increased, and platelet production time was not shortened in 6 patients studied during crisis. These observations do not support the occurrence of a marked degree of platelet activation and consumption in sickle cell anaemia.
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