AN IMMUNOTOXICITY ASSESSMENT OF FOOD FLAVORING INGREDIENTS

A rapid screening protocol incorporating key elements of the US Nation al Toxicology Program's immunotoxicity tier testing strategy was used to evaluate the effects of 35 commonly used food flavouring ingredient s on humoral and cell-mediated immune responses. The test compounds we re administered intragastrically on a daily basis for 5 days at three dose levels to female CD-1 or B6C3F(1) mice, 6-8 wk old. A host resist ance assay (Listeria monocytogenes bacterial challenge) was conducted to assess cell-mediated immunity. Humoral immunity was measured by the antibody plaque-forming cell (PFC) response to sheep erythrocytes. Bo dy weights, lymphoid organ weights and spleen cellularity were also me asured. Cyclophosphamide (80 mg/kg) served as an immunosuppressive pos itive control agent. The results indicated that the majority of the fl avouring ingredients tested did not modulate the cell-mediated or humo ral immune response. However, at very high dose levels, two of the mat erials tested, peppermint oil and citral dimethyl acetal, did increase mortality rate and reduce survival time in the host resistance assay. Neither of these materials significantly altered the PFC response. Th is rapid, economical screening battery for potential immunotoxicants p roved to be a useful means of evaluating a large number of structurall y diverse compounds and mixtures to prioritize them for more definitiv e testing.