Cellular events in tolerance. IV. The effect of a graft‐versus‐host reaction and endotoxin on hapten‐ and carrier‐specific tolerance

The induction of hapten‐specific and carrier‐specific unresponsiveness has been used as a model of B and T cell unresponsiveness, respectively. Endotoxin (lipopolysaccharide (LPS)) and a graft‐versus‐host (GVH) reaction were then evaluated for their ability to interfere with the induction of B and T cell tolerance in vivo. It was found that LPS, but not a GVH reaction had adjuvant activity in that LPS could convert a B cell tolerogenic signal into an immunogenic one. However, both treatments could partially prevent B cell tolerance induction with trinitrophenyl‐isologous IgG. Under conditions in which the GVH‐induced immunosuppression was minimal, carrier (T cell) tolerance was also reduced by the GVH reaction. LPS did not directly interfere with carrier unresponsiveness. We conclude that LPS can block the induction of unresponsiveness in B cells, whereas a GVH reaction can partially affect both T and B cell tolerance induction.