“…Bacterial strains of E. coli K12 C600 (PCM 2184), E. coli strain B (PCM 1935) and Vibrio cholerae NAG (clinical isolate) were obtained from the collection of the Institute of Immunology and Experimental Therapy, Wrocyaw, Poland. Lipopolysaccharides were prepared with phenol-water extraction method (Westphal and Jann, 1965) and purified on Sepharose 2B column in 0.01 M NH 4 HCO 3 (Romanowska, 1967) as detailed previously (Rybka et al, 2003). Samples of rat serum from previous investigation (Szponar et al, 2003) were used.…”