Mechanism of follicular antigen trapping. Evidence for a two cell mechanism using double isotope autoradiography.

Normal mice were intravenously injected with I-labelled HGG—anti-HGG complexes and 2 weeks later with I-labelled HGG—anti-HGG complexes. One week after the last injection the mice were killed and the localization of I and I in the spleen was studied using a double isotope autoradiographic stripping technique. It appeared that I-labelled HGG—anti-HGG and I-labelled HGG—anti-HGG complexes were both localized in exactly the same sites of the splenic follicle centres. It was concluded that both immune complexes were retained by the same dendritic cells. I-labelled HGG—anti-HGG complexes however were still localized in the periphery of the follicles shortly after injection at a time when I-labelled HGG—anti-HGG complexes were already present in the follicle centres. If indeed cells carry immune complexes from the periphery of the follicles towards the follicle centres as suggested by previous studies, the present findings confirm that immune complexes are transferred from these cells to other cells (dendritic cells) in the follicle centres.