In a process for treating eucaryotic cells, in applications in which the toxicity of lipopolysaccharides has an adverse effect, substances are used during transfection or to clean the foreign material which bond lipopolysaccharides and neutralise their toxicity. The process is of particular advantage when foreign material is to be inserted in the cells, especially in gene transfer methods. Compositions containing a lipopolysaccharide-bonding substance are used in cell culture applications as a medium and in therapeutic applications as medicaments.