The influence of specific antibodies and cellular immunity in the induction of tolerance of chemotactic activity caused by Bacteroides fragilis lipopolysaccharide.

Exudate aspirated from wound chambers implanted subcutaneously on rabbits at different time intervals after local lipopolysaccharide (LPS) injection, showed a peak of chemotactic mediator concentration in vitro about two hours before the peak of polymorphonuclear lekocytes accumulated in vivo was demonstrated. Injection of LPS locally into the wound chambers three days after the first injection of LPS showed a reduced number of PMNs accumulated in the exudate. Antibodies to the LPS preparation were demonstrated in the exudate and serum by indirect haemagglutination of sheep erythrocytes before the second LPS injection. This antibody titre increased up to two weeks after the first LPS injection, and was slightly higher in the serum than in the exudate. Also, a migration inhibition factor (MIF) activity was demonstrated in the exudates formed. This MIF activity of the exudates increased after the second LPS injection. The increased titre of specific antibody may indicate an accelerated clearance of LPS, and the MIF activity may indicate a reduced response of PMNs to chemotactic mediators. However, the involvement of other biological mechanisms contributing to the decreased response, cannot be excluded.