Skin irritancy and sensitivity to laundry detergents containing proteolytic enzymes. Part II.

The late type contact sensitizing effect of alkaline protease enzymes (PE) on the intact human skin has been investigated in the present study. The immune process of sensitisation was induced with "Tenzym prilled" (TP, Grindstedvoerket) and with "Maxatase" (M, Gist-Brocades) protease enzymes in the epicutaneous test (ET), using concentration series and various durations of application. The ETs were made on the intact (symptom-free) skin, as well as under conditions promoting the subcorneal penetration of PE. Challenge was carried out at 21 to 30 days following induction of 2092 subjects, and at 2 to 5 months on 1624 subjects. Despite the large number of subjects tested, contact sensitisation developed in none of the cases, although the inducing exposure took place under conditions promoting the immune process of sensitisation. In 60 individuals suffereing from occupational dermatitis on regular contact with PE and having no symptoms of early type inhalative allergy (mucous membrane changes, bronchial asthma-like symptoms) were challenged also by the intradermal test. No reaction was noted in any of them at 10 and 30 minutes, as well as at 24 and 48 hours following the test. Next the influence of PE is analysed in the induction or increased severity of the irritation caused by bioactive laundry detergents. The studies involved the use of serial dilutions of "Biopon" (Bn) laundry detergent containing TP or M, or not containing PE, respectively, by means of the ET. A total of 740 series (5220 tests) of the three variants were applied in dilution series to intact skin surface, as well as to pathologically and arteficially lsioned skin areas. The Bn variants containing and not containing PE increased the number of irratative reactions in essentially the same degree. This suggests that the irritative effect is not due to the presence of PE, but to the laundry-active detergents (WAS) of Bn in the first place, and to a lesser extent to its other ingredients.