Radiolabelled lactoferrin in the detection of occult sepsis

The morbidity and mortality of abdominal abscess is predominantly due to delay in diagnosis. 111Indium labelled leucocytes accurately localise sepsis, but as specialist facilities are required, 111In-lactoferrin which may label leucocytes in vivo and 99Tc-pyrophosphate leucocytes were evaluated as alternatives. Chronic abscesses were produced in 114 Wistar rats by inoculating an intraperitoneal sponge with mixed faecal bacteria. Two weeks later 111In-lactoferrin, 99mTc-pyrophosphate leucocytes or 111In-mixed leucocytes were injected. The mean (± sem) percent injected radioactivity per gram of abscess of 0.36 ± 0.02 with 111In-leucocytes was similar to that of 0.28 ± 0.03 with 111In-lactoferrin (NS) but both were significantly more than 0.18 ± 0.02% achieved by 99Tc-pyrophosphate (p <0.01). The radiation dose to the spleen was reduced with 111In-lactoferrin compared to both 111In-leucocytes and 99mTc-pyrophosphate leucocytes (p <0.01). 111In-lactoferrin may be used to image abscess with the dose of radiation to the critical organ lower than that with 111In-leucocytes.