Liposomes containing 3-n-pentadecylcatechol induce tolerance to toxicodendron.

Pentadecylcatechol (PDC) (1 mg) incorporated into liposomes (PDC-liposomes) and given by intracardiac injection to guinea pigs 1 week prior to attempted topical sensitization to PDC significantly inhibited that sensitization as evidenced by patch tests done 2 weeks after the attempted topical sensitization. PDC (1 mg) dissolved in ethanol did not significantly inhibit sensitization. Sensitization inhibition was specific since dinitrochlorobenzene sensitization was not inhibited by prior intracardiac treatment with PDC-liposomes. In addition, the sensitization to PDC was no longer inhibited if the time between the intracardiac PDC-liposome injection and the topical PDC sensitizing dose was increased from 1 week to 2 or more weeks.