A B S T R A C T The detection of platelet isoantibodies by the release of ['H]serotonin from platelets has been evaluated. The conditions for optimal release of ['H]serotonin with platelet isoantibodies using a microtechnique have been defined. A group of cardiac surgery patients were followed pre-and post-transfusions, with 48% developing a positive serotonin release assay. Of these patients, 16% also had a platelet complement-fixing and/or lymphocytotoxic isoantibody. There was variation in the degree of correlation between ['H]serotonin release and lymphocytotoxicity using individual National Institutes of Health typing serum. The matching obtained between family members by both techniques showed a close correlation when each technique was evaluated separately using the same NIH typing serum. The detection of isoantibodies in patients with hematological malignancies correlated with the unresponsiveness to unmatched platelet transfusions in 15 out of 17 cases. The use of the patient's isoantibody to matched platelets of family members by ['H]serotonin release correlated well with the clinical response to transfusion with these platelets. The data suggest that (a) platelet isoantibodies can be

The authors have developed an improved assay for von Willebrand factor (VIIIVWF) utilizing 4% dimethylsulfoxide (DMSO) to freeze formalin-fixed washed platelets. A platelet aggregometer is used to conduct the assay. The platelets are thawed and an activity curve is established using normal pooled plasma to support ristocetin-induced agglutination. The VIIIVWF level in unknown plasma can then be measured. The platelet preparation is stable for more than a year. Correlation of VIIIVWF measured by this system and Factor VIII antigen (VIIIAg) measured by electroimmunodiffusion was excellent. This is evidence that these two properties reside on the same molecule. Neither VIIIVWF nor VIIIAg correlates well with Factor VIII antihemophilic factor (VIIIAHF).

The clinical, hematologic, and histological characteristics of two patients who progressed from refractory anemia to acute leukemia are described. When first studied, nuclear bridging of erythroblasts, similar to that seen in congenital dyserythropoietic anemia type I and megakaryocytic dysplasia, were the only abnormalities. Within 6 years, both patients died, the first of acute nonlymphocytic leukemia, the second of erythroleukemia. Nuclear bridging of erythroblasts in the marrow of these patients was an early and transient phenomenon and was not observed during the terminal phase of leukemia.

Phytohemagglutinin and poly-L-ornithine were tested for their ability to stimulate uptake of transferrin-bound zinc by lymphocytes from both normal donors and donors with chronic lymphocytic leukemia. The ratio of zinc uptake in poly-L-ornithine cultures to zinc uptake in phytohemagglutinin cultures was 0.9 +/- 0.3 for leukemic lymphocytes and 1.9 +/- 0.2 for normal lymphocytes. Results indicated that this technique may be useful in the diagnosis of chronic lymphocytic leukemia as well as in the assessment of the efficacy of chemotherapeutic regimens.

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