B cell tolerance induced by polymeric antigens. I. Comparison of the dose and epitope density requirements for inactivation of primed and unprimed B cells in vivo.

Hapten [2,4-dinitrophenyl (DNP)]-specific tolerance was induced in nonimmune or DNP-hemocyanin (DNP-KLH) primed mice by administering hapten-conjugated type 3 pneumococcal polysaccharide (DNP-lys-S3). The dose of DNP-lys2.5-S3 required to suppress the primary anti-DNP antibody responses was approximately ten times higher than that required to suppress the secondary response. Large doses of lightly substituted antigen (DNP-lys0.6-S3) had no effect on primary antibody responses, while small doses of this conjugate suppressed 90-95% of the secondary response. The conclusion from this (presumably B cell) tolerance model is that B lymphocytes "mature" in their susceptibility to tolerization following primary contact with immunogen, since primed cells are inactivated by lower doses of tolerogen, and by tolerogen with lower epitope density, than nonimmune B cells. These and other data suggest that the tolerance threshold of B lymphocytes is related to their state of differentiation, and especially to their antigen-binding characteristics.