Immune mechanisms of the occupational sensitization with methylen-dyphenyl diisocyanate (MDI)

The aim of this study was to objectify and to clarity some mechanisms of the immune response of the professional sensitization with MDI. 26 workers were tested for sensitization of immediate type (ST with a broad set of indoor allergens and serum MDI-IgE) and of delayed type (ST with a standard battery of antigens for cellular immunity and with MDI), also the lymphocyte sub-populations and their functional state by flow cytometric analysis. The most frequent allergic complaints were: rhinits (70%), skin manifestations (53%), conjunctivitis (35%) and initial bronchial asthma in two cases (12%). We found indoor sensitization in 41% and normal cellular immune reactivity in all the workers tested. Specific MDI sensitization of immediate type was found in 28.5% of the workers and of delayed type--in 70% of the workers with allergic complaints. The laboratory immune indices suggest prevalence of cell--mediated mechanisms for the workers with allergic symptoms--production of INF gamma, responding to stimulation and deficient or insignificant production of IL-4, as well as linear correlation between the data for CMI, INF gamma, and IL-4. Our results suggest the participation of more than one mechanism of immune injury in the clinically manifested allergic reactions.