Peripheral blood anti-coagulated with sodium heparin (25U/ml) form 60 healthy volunteers invariably had a reduced platelet count, when whole blood was mixed in the presence of air. Smear findings similar to those observed in EDTA-induced pseudothrombocytopenia and the counteracting effect of prostaglandin E₁ (1μM) on thrombocytopenia suggest that this thrombocytopenia is due to platelet activation and aggregate formation. Mixing may activate platelets, because the extent of thrombocytopenia had a positive correlation with the air volume and mixing intensity. Aspirin (1.8mM) and 5-HT₂ blocker (sarpogrelate 100μM) also inhibited this phenomenon. These findings suggest that the mechanism of platelet activation might be partly related to arachidonate metabolism and serotonin release. Oxygen appears to have no direct effects. It is suggested that red blood cells and/or white blood cells participate in platelet activation, because platelet aggregation of platelet-rich plasma was less than that of whole blood. 5-lipoxygenase inhibitor had little effect. To measure platelet counts, it appears essential to eliminate the copresence of air in blood samples anti-coagulated with heparin.

View full abstract

A 44 year-old man was admitted to our hospital in October, 1992 with epistaxis. Fifteen months before admission, thrombocytopenia had been pointed out, but he had no bleeding episode. At admission, neither hepatosplenomegaly nor lympha node swelling was observed. Hematological findings were as follows; WBC 10,000/μl, Hb 14.0g/dl, PLT 5,000/μl, including giant platelets. Platelet assciated IgG (PAIgG) was 471ng/10⁷ cells. Bone marrow aspiration revealed normocellularity with moderate increase in the number of mature megakaryocytes, but no dysplastic changes were seen. Biochemical and radiological examinations disclosed neither malignant diseases nor autoimmune diseases. Based on the diagnosis of idiopathic thrombocytopenic purpura, danazol therapy (300mg/day) was started in November, 1992. After initiation of treatment, the platelet count chaged cyclically every 4 weeks. To elecuidate the mechanism of this phenomenon, we periodically evaluated the patient's immunological background. T lymphocyte counts and subset proportions remained almost the same through out the course, whereas NK cell counts and NK activity coincided with the change of the platelet count. These results suggest that in this case NK cells may play a role in the cylic fluctuatilon of platelet count by regulating the immune system.

View full abstract

A 67-year old man noticed swelling of left maxillar in October 1992. Surgical biopsy of the left maxillar tumor revealed the plasmacytoma at the department of oral surgery. The Tumor disappeared after radiation therapy. He was admitted with dizziness and tarry stool in June 1994. We found left cervical and abdominal paraaortic lymphode swellings by the computer tomography.
He died inspite of chemotherapy in December. Autopsy showed that plasma cells diffusely and nodularly invased in all alimentary tract with multiple ulcerations. Invasion was also observed in the liver, lungs, thyroid, heart, kidneys, and adrenals. The plasma cells in the liver showed IgG κ type by tissue immunostain. Diffuse invasion of extramedullary plasmacytoma is very rare in alimentary tract and many other organs. This case may be value to delineate the nature of this disease.

View full abstract