The results of hepatitis B surface antigen (HBs-Ag) testing in a large volunteer blood donor population are described. Counterelectrophoresis and three versions of solid-phase radioimmunoassay technic are compared and evaluated. Initial results suggested that the radioimmunoassay technic are compared and evaluated. Initial results suggested that the radioimmunoassay technic detected more than five times as many reactive donors as did counterelectrophoresis. The specificity of the radioimmunoassay technic has been increased by successive modifications, and recent results show that the technic detects 73 percent more reactive donors than does counterelectrophoresis. Not all of these reactions are specific, and it is estimated that the true gain in detection of HBsAg carriers is 49 percent of the value found by counterelectroesis. The incidence of HBsAg carriers in the America Red Cross donor population is about 1.25 per 1,000.

Samples of platelet concentrate prepared by double plasmapheresis of volunteers were stored at 4 C and 22 C for four to ten days and cultured from 0072 hours on brain heart infusion media, thioglycolate broth, and tryptic soy broth and incubated at 22 and 37 C for 21 days. A closed system was used for 42 units and a limited entry system involving pooling of platelet concentrates was used for 68 units. All 110 units were negative for bacterial contamination at both 4 C and room temperature, based on cultures using multiple media under maximized growth conditions for anaerobic as well as aerobic bacteria. Platelet concentrates handled in both a closed system and a limited entry system and stored up to at least 72 hours at room temperature remained free of bacterial contamination and appeared safe for transfusion.

Several in vitro platelet function assays were examined. Two units of platelets from each of ten volunteer donors were obtained by plasmapheresis, stored three days, and examined by various functional parameters. The second unit of platelets from an individual had generally lower functional parameters than the first, suggesting a subtle physiological change in the donors' circulation between the time of drawing the first and second units. For in vitro comparisons, this difference was overcome by a pooling procedure. Platelet storage was examined at room temperature and at 4 C.

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