A prospective study of macrophage migration inhibitory factor as a marker of inflammatory detection

This study was to evaluate whether macrophage migration inhibitory factor (MIF) can be used as a better marker of inflammatory detection through the biodistribution and inflammatory imaging study with (131)I-labelled anti-MIF McAb and control antibody in inflammatory model mice. The mRNA and protein expression of MIF in inflammatory lesions were proved by RT-PCR and immunohistochemistry. The model mice were injected with 3.7 MBq of each agent and killed at 24, 48 and 72 hrs after injection. Whole-body images were obtained with storage phosphor screen. The organs, blood, abscesses muscles were removed, weighed and counted with a gamma counter. The percentage of uptake by organs and per gram tissues and abscess/normal tissue (%ID/g) concentration ratios were calculated. The abscesses in mice were well visualized from 24 hrs. The target-to-non-target (T/NT) ratios were 6.71 +/- 1.09 (24 hrs), 8.57 +/- 0.81 (48 hrs) and 11.41 +/- 0.37 (72 hrs) for (131)I-labelled anti-MIF McAb group; while in control group of (131)I-IgG, T/NT ratios were 4.65 +/- 0.63 (24 hrs), 6.44 +/- 0.60 (48 hrs) and 8.23 +/- 0.35 (72 hrs) (P < 0.05). MIF mRNA expression was threefold increased in inflammatory tissues at 24 hrs compared with normal tissues, and twofold increased at 48 hrs. MIF protein expression was stronger in the inflammatory tissues at 48 hrs after focal inflammation occurred. Our findings suggest that the (131)I-labelled anti-MIF McAb appears to be more specific and suitable than (131)I-labelled IgG for targeting focal inflammation, which means MIF can be used as a better marker of inflammatory detection.