The kinetics of leucocyte migration into rabbit knee joints elicited by preformed immune complexes with different in vitro characteristics.

Immune complexes were formed in vitro with antibodies obtained from rabbits immunized with bovine serum albumin in Freund's complete (FCA) or incomplete (FIA) adjuvant. The antibodies were mixed with different amounts of antigen. Immune complexes formed at maximum precipitation proportions were efficient in complement activation, whereas immune complexes formed at antigen excess had weak complement-activating properties. When injected into rabbit knee joints, the immune complexes formed at maximum precipitation proportions with FCA or FIA antibodies caused a moderate leucocyte migration into the joints with maximum cell counts 6-8 hr after injection. Injection into the joints of immune complexes formed with FCA antibodies at antigen excess induced a pronounced leucocyte migration with maximum numbers 18 hr after injection. Immunofluorescent studies indicated that these immune complexes became associated with the leucocyte membrane, whereas immune complexes formed at maximum precipitation proportions were found in the leucocyte granulae, indicating that only the complement-activating immune complexes were efficiently eliminated.