In vivo decomplementation of mice with cobra factor completely prevented trapping of aggregated human IgG within splenic germinal centres. Observations of the intrasplenic position of the aggregated material within 8 hr of its injection into normal and decomplemented mice suggest that the early phase of localisation in germinal centres depends on binding to lymphocyte C3 receptors.

No abstract

The effect of nonspecific mitogens on the trapping of 125I-labeled aggregated human IgG (125I-AHGG) in germinal centers (GC) of mouse spleens has been investigated by both radioactivity uptake and immunofluorescence. Phytohemagglutinin and concanavalin A (Con A) significantly decreased trapping. Lipopolysaccharide produced less inhibition, and pokeweed mitogen had no significant effect. The maximum inhibition occurred with 250--500 mug Con A. This had no effect on 125I-AHGG uptake in liver kidney and blood. No differences were found between i.p. and i.v. routes of Con A injection. The effect of mitogens on the 125I-AHGG trapping in GC is due more likely to modification of the migratory properties of lymphocytes brought about by surface binding, than to their mitogenic properties, since Con A decreased 125I-AHGG localization in thymectomized, x-irradiated and bone marrow-reconstituted animals.