Antigenicity study of muroctasin.

Antigenicity study of N2-[(N-acetylmuramoyl)-L-alanyl-D-isoglutaminyl]-N6-stearoyl-L-lysi++ + ne (MDP-Lys(L18), muroctasin) was carried out in mice, guinea pigs and rabbits with passive cutaneous anaphylaxis (PCA), systemic anaphylaxis (SA), Arthus and delayed skin reaction and enzyme-linked immunosorbent assay (ELISA). Mice were sensitized intraperitoneally, twice at 3-week intervals, with MDP-Lys(L18) (40, 400 or 4000 micrograms/kg) or MDP-Lys(L18)-ovalbumin (OA) conjugate (500 micrograms/kg) in alumina gel. No IgE antibodies to MDP-Lys(L18) were detected in the sera obtained from the sensitized mice by 24-h PCA in rat. Guinea pigs were sensitized subcutaneously with MDP-Lys(L18) (4, 40 or 400 micrograms/kg) or MDP-Lys(L18)-OA (2 mg/kg) emulsified in Freund's complete and incomplete adjuvant, 3 times at 2-week intervals. No SA was observed in the sensitized animals after the intravenous injection of MDP-Lys(L18) (1 mg/kg). Rabbits were sensitized subcutaneously with MDP-Lys(L18) (2 or 20 micrograms/kg) or MDP-Lys(L18)-OA (2 mg/kg) emulsified in Freund's incomplete adjuvant, 3 times at 2-week intervals. Neither Arthus nor delayed skin reaction was observed in the sensitized animals after the intradermal injection of MDP-Lys(L18) (2 micrograms/site). Although antibodies to MDP-Lys(L18) were not detected in MDP-Lys(L18) sensitized animals, the antibodies were detected in two out of 9 guinea pigs and all of the rabbits in the MDP-Lys(L18)-OA sensitized groups by 4-h PCA after the intravenous injection of MDP-Lys(L18) (1 mg/kg). These results suggest that MDP-Lys(L18) may possess antigenic potential by PCA reaction in guinea pigs.