Nickel contact sensitivity in the guinea pig. An efficient open application test method

Nickel contact sensitivity was successfully induced in guinea pigs using an open epicutaneous application method. Immediately after pretreatment with 1% aqueous sodium lauryl sulfate, upper back skin was treated daily for 4 weeks with 0.3%-3% nickel sulfate in either a 1% lanolin cream (Vaseline, pH 5 SAD crème) or hydroxypropyl cellulose. Weekly intradermal injections with aluminium potassium sulfate were used as adjuvant. The animals were challenged twice with a one week interval, with nickel sulfate 2% in water and 1% in petrolatum, respectively. The response rates in the test groups treated with nickel sulfate 1% or 3% in the lanolin cream or 1% in hydroxypropyl cellulose were significantly different from the response rate in the control group. Considering both readings at both challenges, the frequency of sensitization was 57-93% (8 of 14 to 13 of 14 animals) in the group treated with 1% in the lanolin cream, 60-100% (9/15 to 15/15 animals) in the group treated with 3% in the lanolin cream, and 67-75% (8/12 to 9/12 animals) in the group treated with 1% in hydroxypropyl cellulose. Rechallenge of initially sensitized animals 10 weeks later confirmed that a lasting contact allergy had been obtained.