Inhalation challenge and pharmacologic studies of toluene diisocyanate (TDI)-sensitive workers.

Workers with "sensitivity" to toluene diisocyanate (TDI) studied in depth in an attempt to determine mechanisms of bronchial hyperreactivity. Tests included provocative inhalation challenge (PIC) with TDI and methacholine challenge. Blood samples obtained prior to and at various times after PIC were used to measure complement and split products of complement and plasma histamine levels and to determine dose-response slopes of lymphocyte cyclic adenosine monophosphate (cAMP) following stimulation with agonists. TDI-reactive individuals were all reactive to methacholine and responded to PIC with TDI by immediate, delayed, or dual bronchospastic reactions. No change in plasma histamine, total complement levels, or split products of complement were measurable. TDI reactors gave decreased lymphocyte cAMP dose response slopes to stimulation with isoproterenol, prostaglandin E1, and TDI, which suggests that impairment of adrenergic receptors may play an important role in TDI reactivity.