Lymphocyte transformation and thiuram sensitization

The use of a lymphocyte transformation test (LTT) to confirm allergic contact dermatitis from thiurams has been investigated. The responses of peripheral blood mononuclear cells (PBMC) from thiuram-sensitive and non-sensitive individuals following culture with dimethylcarbamoyl-protein (human serum albumin; HSA) and dimethylthiocarbamoyl-HSA conjugates has been compared. Only PBMC from those patients who were patch-test-positive with thiuram-mix and sensitized to tetramethylthiuram monosulphide (TMTM) or TMTM and tetramethylthiuram disulphide (TMTD) exhibited significant proliferative responses to these conjugates. Thiuram-patch-test-negative patients and control donors with no history of allergic contact dermatitis failed to mount a significant response to any concentration of either conjugate. Two of the thiuram-sensitive patients were also nickel-patch-test-positive, and PBMC isolated from these donors, but not from nickel-patch-test-negative patients, proved positive in a nickel LTT. The data reveal that relevant hapten-protein conjugates are capable of provoking specific human lymphocyte proliferative responses in vitro, and that, using this technique, the LTT can, in principle, be used for the investigation and/or diagnosis of skin sensitization to lipophilic contact allergens.