The study investigates isocyanate antigen-driven T-cell responses in vitro-, following in vivo exposure using patient samples acquired through collaboration with ongoing field epidemiological and clinical studies. The study compares isocyanate antigen-reactive T-cells from primary exposure sites (skin/lung) with those from blood, to evaluate potential routes of sensitization and identify diagnostic indicators of isocyanate sensitivity/susceptibility. Specifically, the study : generates and characterizes hexamethylene diisocyanate (HDI) antigens including isocyanate metabolites, and isocyanate conjugated t normal human and foreign proteins; evaluates the T-cell antigenicity of the HDI antigens, based on blood and lung lymphocyte proliferation, cytokine production, and phenotype in order to identify the molecular form of HDI that initiates airway cytokine production in asthma patients; establishes T-cell lines from the skin, lung and peripheral blood of HDI asthma patients and characterizes the phenotype, antigen specificity, cytokine production and TCR expression of isocyanate responsive T-cells in these different compartments; compares isocyanate responsive of T-cells found in the skin, lung and blood and correlates with clinical sensitivity to determine characteristics associated with exposure and sensitization leading to clinical asthma.