Follicular trapping of hapten-erythrocyte-antibody complexes in mouse spleen.

In this study we followed the in vivo fate and distribution of hapten-coupled sheep red blood cells (TNP-SRBC) coated with 125I-labelled anti-hapten antibody in mice. The majority of these complexes was rapidly taken up by the liver, and by macrophages in the marginal zone of the spleen. Within a few hours, however, marginal zone labelling diminished and label appeared in the corona of lymphoid follicles. After 1-7 days the only remaining label was associated with areas of follicular dendritic cells. This follicular trapping was abolished by decomplementing mice with cobra venom factor. These results, therefore, demonstrate that immune complexes made with a large, particulate antigen are retained for long periods in lymphoid follicles in an analogous fashion to soluble complexes. We assume (but have not proved) that the complexes retained by dendritic cells contain soluble erythrocyte antigens released from macrophages, rather than intact RBC. This possibility is strengthened by the presence of significant amounts of free, functional antibody in the circulation of mice given TNP-SRBC coated with antibody in vitro. The possible significance of immune complex trapping in antibody-induced suppression of anti-RBC responses is discussed.