The use of external monitoring to study splenic trapping of 51Cr-tagged heat-treated erythrocytes

Previous investigators proved that heat-produced spherocytes were rapidly removed from the circulation by the spleen, whereas cell fragments were slowly captured in the rest of the reticuloendothelial system. In vitro experiments demonstrated that the highest yield of heat-produced spherocytes (85%+-5,7) was obtained by heating in a water bath at 500 for 15 minutes, using 1 ml ACD for every 3 ml blood. Using 51Cr-tagged erythrocytes treated under these standardized conditions, radioactivity disappearance from the circulation was studied on 20 normals by external monitoring, using two matched detectors placed over the sternum and spleen. Radioactivity dissappearance curves recorded by the sternal detector simulated a multiexponential function of time. After subtraction of the slow component the disappearance half time was calculated and amounted to 4,8+-1,4 minutes, the range being 2,3 to 9,0 minutes. From the simultaneously recorded splenic radioactivity build-up tracings Tsub(1/2) of thermally damaged erythrocytes averaged 6,1+-2,1 minutes, with a range from 3,5 to 10,3 minutes. Results obtained from splenic build-up curves showed better spread over the full range of obtained values, without being affected by extrasplenic reticulo-endothelial structures