Black henna, Henne, Persulphates, Red henne, Senne, Sericin
Incidence: strongly associated with atopic subjects. In the case of allergy to henna and sercine, an IgE-dependent mechanism has been identified. However, for ammonium thioglycolate (setting agent) the mechanism remains to be determined. An hypersensitive pulmonary disorder may arise in some subjects using synthetic hair lacquer resins. Persulphates constitute a major irritant. Skin tests with persulphates have been inconclusive and a specific form of IgE has never been demonstrated. They act as direct histamine liberators in vitro.
The combination of exposure to irritants and allergens in a work place which is typically poorly ventilated, without extractor fan, is the main source of the problem. The persulfates which are used in bleaching have been proved statistically to be the major cause. In factories producing persulfates, it has been shown that ambient levels below 1 mg per m2 of air protects against sensitization.
The first symptom is rhinitis which occurs within minutes of contact.
Classic asthma linked to work is often also present. Urticaria and facial oedema are common symptoms and eczema has also been reported.
Eczema on the hands is also very common.
Skin tests: henna and sericin.
Immunological assay: RAST sericin. Tests must be conducted in hospital (powders may be dangerous when mixed). Delayed reactions are possible with bronchial provocation test.
Skin tests are positive in 24% of cases. Bronchial hyperreactivity exists in 58% of cases and BPT is only present in 22%. (Schwaiblmair et al).
Comparison of tryptase and ECP levels before and after bronchial provocation tests is an additional possibility in aetiological diagnosis.