アラキドン酸代謝に異常を認めずＡ２３１８７による凝集障害を示した新しい血小板放出機構異常症の一家系 [in Japanese] A family of platelet release mechanism abnormality with normal arachidonate metabolism and defective response to ionophore A23187 [in Japanese]
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Three cases in a family with platelet release mechanism abnormality who had intact arachidonate metabolism and defective response to ionophore A23187 were reported.<br>The proband was a 3 year old boy who showed prolonged bleeding time, small platelet volume and normal clot retraction. No second wave of aggregation with ADP, epinephrine or ristocetin and poor aggregation with collagen were observed. ATP release, investigated with a lumi-aggregometer (Chrono-log Co.), was not detected during the aggregation. Not only arachidonate (2mM at final concentration) but also A23187 (10, 20μg/ml at final concentration) failed to induce the aggregation or release reaction of his platelets. In normal subjects who ingested either aspirin or indomethacin, A23187-induced aggregation and release were normal. Production of metabolites of <sup>14</sup>C-arachidonic acid assessed by thinlayer radiochromatogram was normal. Platelet lysate prepared from the patient caused the aggregation of normal platelets as well as lysate from normal subjects, and the amount of platelet adenine nucleotides was within the normal range. His sister and mother were revealed to have similar defects to those of the proband.<br>From these results, it was assumed that abnormality of release mechanism in these patients was not due to defective arachidonate metabolism (either phospholipase A<sub>2</sub>, cyclo-oxygenase or thromboxane A<sub>2</sub> deficiency) but was attributable to defective mobilization of Ca<sup>++</sup> into the cytoplasm and/or abnormal interaction between Ca<sup>++</sup>, thromboxane A<sub>2</sub> and cyclic AMP. These cases and three patients in another family with similar defects previously reported by us (Takahashi, et al., 1978) might be a new type of platelet release mechanism abnormality.
- Blood & Vessel
Blood & Vessel 12(2), 223-228, 1981
The Japanese Society on Thrombosis and Hemostasis