Guinea pig maximization test, open epicutaneous test and chamber test in induction of delayed contact hypersensitivity.

A comparison was made between the guinea pig maximization test (GPMT), open epicutaneous test (OET) and chamber test (CT), and the allergens were neomycin sulphate and propylene glycol (PG). The sensitization rate for neomycin in petrolatum was 35% in GPMT, 25% in OET and 25% in CT. The corresponding figures for neomycin in PG were 30% in GPMT, 45% in OET and 32% in CT. PG caused no hypersensitivity in 118 guinea pigs. The results suggested that as a hygroscopic, irritant and penetrating vehicle PG facilitates the induction of delayed contact allergy, especially in OET.