OPTIMIZED LOCALIZATION OF BACTERIAL-INFECTIONS WITH TC-99M LABELED HUMAN-IMMUNOGLOBULIN AFTER PROTEIN CHARGE SELECTION

To improve the scintigraphic detection of bacterial infections a prote in charge-purified fraction of polyclonal human immunoglobulin was app lied as a radiopharmaceutical. This purification was achieved by attac hing the immunoglobulin to an anion-exchanger column and by obtaining the column-bound fraction with buffer. The binding to bacteria in vitr o and the target to non-target ratios of an experimental thigh infecti on with Staphylococcus aureus or Klebsiella pneumoniae in mice were ev aluated to compare the purified and the unpurified immunoglobulin. The percentage of binding to all gram-positive and gramnegative bacteria used in this study was significantly (P<0.03) higher for the purified than for the unpurified immunoglobulin. For the in vivo study, mice we re infected in the thigh muscle with Staph. aureus or K. pneumoniae. A fter 18 h 0.1 mg of technetium-99m labelled polyclonal immunoglobulin or Tc-99m-labelled protein charge-purified polyclonal human immunoglob ulin was administered intravenously. At all time intervals the target (infected thighs) to non-target (noninfected thighs) ratios for both i nfections were significantly higher (P<0.03) for protein charge-purifi ed polyclonal immunoglobulin than for unpurified polyclonal human immu noglobulin. Already within 1 h the infected tissues could be detected by the purified immunoglobulin. It is concluded that Tc-99m-labelled p rotein charge-purified immunoglobulin localizes both a gram-positive a nd a gram-negative thigh infection more intensely and faster than Tc-9 9m-labelled unpurified immunoglobulin.