B-cell activating properties of polymyxin B.

Polymyxins are known to be inhibitors of certain polyclonal B cell activators such as lipopolysaccharide and dextransulphate. However, increased specific responses to hapten-coupled mitogens have been reported after the addition of polymyxins to superoptimal conjugate doses. In this paper we have studied the effect of polymyxin B on superoptimal polyclonal doses of lipopolysaccharide. Results similar to those reported for hapten-lipopolysaccharide conjugates were obtained. Polymyxin B was also found to exert adjuvant properties for a primary immune response to sheep erythrocytes and to be a thymus-independent antigen.