Use of contact hypersensitivity in immunotoxicity testing

Area of Science:

• Immunotoxicology
• Cellular Immunity Assessment

Background:

• Preclinical immunotoxicity assessment relies on lymphoid organ histopathology and T-dependent antibody response assays.
• Cellular immunity evaluation, including lymphocyte proliferation and hypersensitivity models, can supplement standard testing.

Purpose of the Study:

• To describe contact hypersensitivity (CHS) models as methods for assessing cellular immunity in preclinical immunotoxicity testing.
• To highlight the methodology and application of CHS models in mice and guinea pigs.

Main Methods:

• Contact hypersensitivity testing involves topical application of sensitizers in three phases: sensitization, rest, and elicitation.
• In mice, the ear-swelling test measures cell-mediated response via ear thickness changes.
• In guinea pigs, CHS response is assessed by erythema and edema magnitude on challenged skin.

Main Results:

• Immunosuppressive chemical exposure significantly reduces ear swelling or skin reactions in CHS models.
• CHS models reflect cell-mediated immune responses to topical sensitizers.

Conclusions:

• Contact hypersensitivity models offer a means to evaluate cellular immunity in preclinical settings.
• These models are currently underutilized in immunotoxicity testing due to limited standardization, validation, and species restrictions (mice, guinea pigs).