STUDIES OF QUALITY-CONTROL OF TC-99M-LABELED MACROAGGREGATED ALBUMIN .1. AGGREGATION OF NON-MERCAPTALBUMIN AND ITS CONFORMATION

The aggregative condition of albumin was investigated using bovine serum albumin (BSA) as a model for quality control of Tc-99m-macroaggregated albumin (Tc-99m-MAA). Uniformalized aggregates were obtained from the oxidized non-mercapt-type of BSA by heating. The size of the aggregates was affected by the pH and the types of buffer solutions used as well as the concentrations of albumin and buffers. The beta form structure of the albumin was more stable on heating and this may contribute to its aggregation. Aggregation of oxidized non-mercaptalbumin afforded a portion of smaller sized particles in MAA, this being an inappropriate factor for scintiscanning of lungs. Our results suggest that it is necessary to remove oxidized type albumin from human serum albumin as the starting material, in order to prepare MAA with a uniform and larger particle size.