7-oxodehydroabietic acid, a resin acid found in both aerosol from soldering with rosin flux and in rosin solids. In a murine model, conjugation (haptenation) of resin acids to proteins is required to generate antibodies against rosin. Conjugation of L-lysine to 7-oxodehydroabietic acid was predicted, with a Schiff base (or imine) linkage formed between C-7 of the resin acid and a free amino group of lysine. Resin acids accumulate in the plasma membrane, a non-aqueous environment apparently conducive to conjugation of 7-oxodehydroabietic acid with lysine side chains of membrane proteins. The result would be dehydroabietic acid covalently bound to protein, which could lead to interaction with immune cells having resin acid specificity. The haptenation mechanism presented may be involved in allergic contact dermatitis and occupational asthma observed from exposure to resin acid solids and aerosols.