Immune complexes in the spleen. The difference between competitive inhibition of immune complex trapping in spleen follicles and inhibition by paratyphoid vaccine.

Paratyphoid vaccine injected between 4 days and 3 hours before injection of labelled immune complexes (125-I-labelled BGG-anti-BGG), inhibits follicular trapping of these complexes in the mouse spleen. Inhibition is maximal when paratyphoid vaccine is given 1 day before, almost no label being found in the spleen follicles. No inhibition of follicular trapping of the complexes occurred when paratyphoid vaccine was injected simultaneously with the labelled immune complexes. Competitive inhibition was found when unlabelled immune complexes were given together with labelled immune complexes. Simultaneous injection of mice with paratyphoid vaccine and labelled immune complexes resulted in an additonal form of localization of the labelled immune complexes in the white pulp, heavily labelled clumps also appearing in the periarteriolar lymphocyte sheaths and follicles. The results are discussed in relation to the mechanism of immune complex trapping in spleen follicles.