In vitro studies in nickel allergy: diagnostic value of a dual parameter analysis.

A comparison was made between the diagnostic value of assaying nickel-induced lymphocyte proliferation (lymphocyte transformation test, LTT) and migration inhibition factor (MIF) production in nickel contact sensitivity. Although lymphocyte proliferation was significantly increased in the group of patients with skin test reactivity to nickel, positive LTT were also frequently found in skin test-negative subjects: in 63% of subjects with and in 30% of subjects without a history of metal allergy. This would limit the value of the LTT as an in vitro correlate of skin test reactivity. However, in certain patients positive lymphocyte transformation may reveal nickel sensitization at a time of undetectable skin reactivity. Data obtained with the macrophage migration inhibition test (MMIT) showed a good correlation with nickel patch test reactions. Accurate determination of MIF became feasible by using cells from the human monocytoid cell line U937 as target cells in a microdroplet agarose assay. Using this MMIT, positive reactions occurred in 13% of the healthy controls and false-negative reactions were found in 26% of patients with positive skin test reactivity to nickel. As LTT and MMIT data appeared to be only weakly correlated in the individuals tested, a dual parameter analysis was performed. An excellent correlation [p = 1.8 (10(-8]] was found between skin test and in vitro reactivity for individuals with matching in vitro results (60% of all individuals tested). In those individuals with discordant in vitro data, skin testing will remain indispensable for diagnosing nickel allergy.

Hand eczema in hairdressers and nurses: a prospective study. I. Evaluation of atopy and nickel hypersensitivity at the start of apprenticeship.

A prospective study of the development of hand eczema was initiated in 86 junior hairdressers and 217 junior nurses. Data obtained at the start of their apprenticeships are presented. None of the junior apprentices presented with hand eczema, but a history of hand eczema was reported by 22/303 (7%) of the students. Almost half of this group (10/22, 45%) could be classified as atopics. Students without a history of hand eczema showed a similar frequency of atopy (17%) as observed in the general population. History of hand eczema was not related to nickel hypersensitivity, as assessed by patch testing. The incidence of nickel hypersensitivity was high in junior hairdressers (26%), compared to junior nurses (12%). Information as to previous contacts with nickel suggested that development of nickel allergy had been promoted by ear-piercing. A lower incidence of nickel hypersensitivity was observed if this potentially sensitizing event had been proceeded by orthodontic treatment with nickel-containing materials. This phenomenon is discussed in terms of orally-induced tolerance.