War and Peace Inside - imaging Immune Attack in Blood Vessels

During evolution, immunity has been developed to protect against invading organisms and remove unwanted structures, like malignant cells. Yet, in extreme cases the organisms, like bacteria or parasites, find their way through tissues and can survive even in blood, which contains most elements of the immune system. A drastic example is parasitic Schistosoma mansoni worms that can live within blood vessels for years. Imaging studies have helped us to visualize ways how Schistosoma parasites can escape immune attacks inside circulation. Parasites often escape the immune system by hijacking soluble inhibitors of the blood complement inhibitors. By molecular radioimaging it is also possible to trace the accumulation of these inhibitors to their targets. Specifically, our collaborative work has been able to demonstrate the acquisition of immunoglobulins by adult S. mansoni worms and show the distribution of the complement inhibitor factor H in live animals. Radioimaging can thus be applied not only to detection of tumors and their metastases but to analysis of immune reactions against endogenous and exogenous targets in vivo.