Induction of human interleukin-1 production by polymyxin B.

Lipopolysaccharide (LPS) is a well known interleukin-1 inducer. Polymyxin B sulphate (PMB) is a cyclic antibiotic which neutralizes different biological properties of LPS. Under the conditions used in our laboratory, we were able to show that PMB alone could stimulate human monocytes to produce and release interleukin-1 activity, and that PMB was unable to inhibit the production of interleukin-1 by human monocytes stimulated with LPS. On the contrary, a synergistic effect was obtained which was not observed with another stimulant such as muramyl dipeptide.