Experience has shown some variation in the associations between IgE, atopy, and sensitization to platinum salts. Clarification of these associations, and the value of the parameters in predicting and diagnosing sensitization of workers at risk, required prospective investigation.Objectives
Evaluation of total IgE and Phadiatop® status to establish baseline values, and changes during employment, predictive or associated with subsequent platinum salt sensitization.Methods
A 24-month prospective study, in a South African primary platinum refinery, of a cohort of 78 healthy recruits without evidence of atopy (tested negative to skin prick test with common allergens). Subsequently they were categorized as 22 sensitized (positive skin prick test to platinum salts), 46 not sensitized (negative skin prick test and symptom free), and 10 symptomatic subjects not included in either category.Results
(1) Pre-employment: four (18%) of the subsequently sensitized subjects and eight (17%) not sensitized were Phadiatop® positive. Levels of total IgE > 100 kU/L, present in 16 subjects were associated with positive Phadiatop® status and race. (2) During employment: Phadiatop® status converted from negative to positive in more sensitized (12/18) than unsensitized (6/38) subjects (P ≤ 0.0001). Total IgE levels at outcome had increased in more sensitized subjects, and median levels were higher than in unsensitized subjects (17 (77%) vs six (13%), and 92 vs 26 kU/L, P = 0.0015). Multivariate analysis showed the likelihood of an increase in total IgE was nine times greater in subjects sensitized to platinum salts, and five times greater with higher platinum salt exposure. Specific IgE was demonstrated, generally in only one sample of the series, in two sensitized and three unsensitized subjects. Positive responses to skin prick tests with common allergens occurred in five (23%) sensitized and 11 (24%) unsensitized subjects.Conclusion
Platinum salt sensitivity was not predicted by pre-employment Phadiatop® or IgE status, but was subsequently associated with conversion to positive Phadiatop® status, and an increase in total IgE (independent of Phadiatop® status).