Binding of labelled antigens and immune complexes to macrophages and dendritic cells in cryostat sections of normal mouse spleen.

It has been shown that, when cryostat sections of normal mouse spleens were incubated with labelled immune complexes, label accumulated in the dendritic cell areas of some follicle centres. No label, more than background, was found in the periphery of the follicles. This localization pattern is different from that obtained when labelled immune complexes had been injected intravenously in mice. Apart from the cells involved in follicular trapping of immune complexes, labelled cells were also found in the white pulp, especially in the periarteriolar lymphocyte sheaths and in the red pulp. These cells could be identified as macrophages. When incubation of the cryostat sections took place with labelled antigen, in the absence of the complexing specific antibody, only the macrophages were labelled but not the cells in the follicle centres. These results are discussed in relation to the binding mechanisms of antigens and immune complexes to macrophages and dendritic cells.