Different effects of bacterial lipopolysaccharide on neonatal immunological tolerance to HSA in rabbits and chickens.

Addition of bacterial lipopolysaccharide to HSA during repeated immunization of rabbits neonatally rendered tolerant to HSA led to anti-HSA antibody formation in 4 out of 5 animals. In all 6 tolerant animals immunized with HSA alone tolerance persisted after cessation of the immunization series, as shown by non-immune elimination of 125I-HSA. On the other hand, immunization with HSA together with different doses of LPS did not increase anti-HSA antibody levels in tolerant and control chickens.