Comparison of radioisotope methods and a non-radioisotope method to measure platelet survival in the baboon.

BACKGROUND: The in vivo survival of autologous fresh and preserved platelets can be measured using 51-Cr and 111-In-oxine radioisotope procedures and by a non-radioisotope procedure using biotin-X-N-hydroxysuccinimide (NHS) with detection in the flow cytometer using fluorescent streptavidin. This study was done to assess the specificity of the radioisotopes 51-Cr and 111-In-oxine and non-radioactive biotin-X-NHS to label platelets to measure their in vivo recovery and lifespan. STUDY DESIGN AND METHODS: In the study reported here, aliquots of autologous platelets from the same baboon were labeled with 51-Cr, 111-In oxine and biotin-X-NHS to measure platelet survival. Both cell-associated and platelet-associated 51-Cr and 111-In oxine radioactivity were assessed to measure the in vivo recovery and lifespan of platelets. Blood volume was measured using the 125I albumin plasma volume and the total body hematocrit. RESULTS: In vivo recovery values measured during the 1-3h post-infusion period and during the 8 day post-infusion period showed significant differences between the 51-Cr-labeled and the 111-In-oxine labeled platelets. In the 51-Cr-labeled platelets, the cell-associated radioactivity was about 50% higher than the platelet-associated radioactivity. In the 111-In-oxine labeled platelets, the cell-associated radioactivity was about 10% higher than the platelet-associated radioactivity. Similar in vivo recovery values were observed in the biotin-X-NHS labeled platelets and the 111-In-oxine labeled platelets assessed from the cell-associated 111-In-radioactivity. CONCLUSION: The radioisotope 51-Cr and 111-In are non-specific labels for platelets, whereas biotin-X-NHS is a specific label for platelets identified in the flow cytometer with fluorescent streptavidin. The in vivo recovery values of autologous baboon platelets were similar when assessed from the cell-associated 111-In-oxine radioactivity and biotin-X-NHS labeled platelets.

Circulation and distribution of 111-In-oxine-labeled autologous baboon platelet aggregates and buffy coat.

BACKGROUND: Although it is known that RBC concentrates may contain buffy coat and platelet concentrates may contain platelet aggregates, the circulation and distribution of these materials in the blood products have never been reported. STUDY DESIGN AND METHODS: Baboon platelets were labeled with 111-In-oxine, aggregated with ADP and autotransfused without a filter. Baboon buffy coat was stored at 4 degrees C, labeled with 111-In-oxine and autotransfused without a filter. The circulation of the radiolabeled platelets and buffy coat was measured and the distribution of the buffy coat and platelet aggregates was measured by external scanning of the baboon using a gamma camera. The effects of the infusion of aggregated platelets, buffy coat, and gelatin on the plasma fibronectin level also were evaluated. RESULTS: The 111-In-oxine labeled platelet aggregates were initially sequestered in the lungs and released into the peripheral blood during the next 3h, during which time the cell associated radioactivity increased by about 25%. Following the autotransfusion of 111-In-oxine labeled buffy coat, the 111-In-oxine radioactivity over the lungs increased, but decreased during the 60-min post-transfusion period as the radioactivity over the liver increased. Cell-associated radioactivity increased by about 10% over the 3-h post-transfusion period. Fibronectin levels decreased by 3% following the autotransfusion of platelet aggregates, by 10% after the autotransfusion of buffy coat and by 50% after the infusion of gelatin. CONCLUSIONS: 111-In-oxine radioactivity in the platelet aggregates and buffy coat was initially sequestered in the lungs, and 10-25% of the 111-In-oxine cell-associated radioactivity was released into the circulation during the 24-h post-transfusion period.

Comparison of radioisotope methods and a nonradioisotope method to measure the RBC volume and RBC survival in the baboon.

BACKGROUND: RBC volume, 24-hour posttransfusion survival, and life span can be measured with radio-isotopes and nonradioactive procedures. STUDY DESIGN AND METHODS: RBC volume was measured directly with autologous baboon RBCs labeled with biotin-X-N-hydroxysuccinimide (NHS), 51Cr, 99mTc, and 111In-oxine and indirectly from the 125I plasma volume and the total body Hct. Twenty-four-hour posttransfusion survival and life span were measured in autologous fresh baboon RBCs labeled with 51Cr, 111In-oxine, 99mTc, and biotin-X-NHS. RESULTS: Significantly larger RBC volumes were observed when the fresh autologous RBCs were labeled with 51Cr, 111In-oxine, or 99mTc than when they were labeled with the nonradioactive biotin-X-NHS. Twenty-four-hour posttransfusion survival values were significantly lower in the RBCs labeled with 111In-oxine or 99mTc than in the RBCs labeled with 51Cr. CONCLUSIONS: The greater in vivo elution of 51Cr, 111In-oxine, and 99mTc than that of biotin-X-NHS influenced the measurements of RBC volume, 24-hour posttransfusion survival, and life span of the fresh baboon RBCs.

Circulation and hemostatic function of autologous fresh, liquid-preserved, and cryopreserved baboon platelets transfused to correct an aspirin-induced thrombocytopathy.

BACKGROUND: The survival of fresh and preserved platelets has been used primarily to determine their therapeutic effectiveness. The function of the fresh and preserved platelets has been difficult to assess. In stable thrombocytopenic patients, platelet function of fresh and preserved allogeneic platelets is evaluated by the reduction in bleeding time. In this study of healthy male baboons, both the survival and function of autologous fresh, liquid-preserved, and cryopreserved platelets in the correction of an aspirin-induced thrombocytopathy was evaluated. STUDY DESIGN AND METHODS: Five healthy male baboons were studied on eight occasions over a 4-year period. To produce a prolonged bleeding time, the baboon was administered 325 mg of aspirin 18 hours before receiving autologous transfusion. The fresh, liquid-preserved, and previously frozen washed platelets were labeled with (111)In-oxine before autologous transfusion. The autologous, nonaspirinated platelets' ability to reduce the aspirin-induced prolonged bleeding time and increase the shed blood thromboxane B2 level at the template bleeding time site was studied. RESULTS: Platelets stored at 22 degrees C for 48 hours had in vivo recovery values similar to those platelets stored for 18 hours, and they significantly reduced the bleeding time and increased the shed blood thromboxane level after transfusion. Platelets stored at 22 degrees C for 72 hours had in vivo recovery values similar to those platelets stored for 18 hours, but the bleeding time was not corrected after transfusion, although there was a significant increase in the shed blood thromboxane B2 level. The cryopreserved platelets significantly reduced the bleeding time and significantly increased the shed blood thromboxane level after transfusion. Cryopreserved platelets had better in vivo survival and function than the 5-day liquid-stored platelets. CONCLUSIONS: The survival of autologous fresh, liquid-preserved, or cryopreserved platelets did not correlate with their function to reduce an increased bleeding time in baboons treated with aspirin.