Competition of Soluble Antigens by Tissue Culture Assay

Abstract

Intravenous injection of 10 mg of hemocyanin (KLH) simultaneously with or 24 hr after intravenous injection of 10 mg of bovine serum albumin labeled with S³⁵ (S³⁵-BSA) into rabbits hyperimmunized to both antigens resulted in antibody formation to both antigens by spleen cells in vitro. However, intravenous injection of 10 mg of KLH 9 to 24 hr prior to S³⁵-BSA into similar rabbits caused inhibition of BSA antibody production in vitro. The inhibitory effect was diminished if KLH was given 48 hr or 72 hr prior to S³⁵-BSA and no inhibition occurred if KLH was given 6 days prior to S³⁵-BSA. The inhibition did not appear to be dependent upon excess concentration of S³⁵-BSA in the inhibited cultures and could not be correlated with circulating serum titers just prior to challenge over the period tested or to depletion of nutrients in the medium. The inhibition was dosage-dependent, 10 µg of KLH being inadequate to cause inhibition. The primary or secondary response to KLH was insufficient to cause inhibition of BSA antibody production in vitro by spleen cells from rabbits hyperimmunized to BSA only.