Detection of chromium allergy by cellular in vitro methods

Abstract

Background: The standard assay for the detection of chromium sensitization, the patch test, does not allow discrimination between patients with and without clinical symptoms of allergy.

Objective: The aim of this study was to prove whether cellular in vitro tests are predictive of chromium allergy.

Methods: Chromium-sensitized volunteers with and without clinically manifest allergy and non-sensitized healthy controls (n=37, 19, and 26, respectively) were analysed by cellular in vitro methods using tri- and hexavalent chromium (chromium chloride and potassium dichromate) as stimuli. The results were correlated with clinical and anamnestic data.

Results: Sensitized individuals with an allergy displayed significantly higher lymphocyte transformation test (LTT) responses than sensitized volunteers without allergy and controls (P<0.05 and P<0.01, respectively). 12.5 microg/mL of chromium chloride and 50 ng/mL of potassium dichromate were found to be optimal to discriminate between sensitized individuals with and without allergy. Combining the results of chromium chloride and potassium dichromate LTT, a positive reaction to at least one of the stimuli was highly predictive of allergy [sensitization with vs. without allergy: Odds ratio (OR)=6.4, P=0.004; sensitization with allergy vs. controls: OR=11.5, P<0.0001]. On the contrary, IFN-gamma, IL-2, IL-4, IL-10, and IL-12 production to the ELISpot, patch test results, sensitization against other metals, and atopy score did not significantly discriminate between sensitization with and without allergy. However, IFN-gamma responses towards chromium chloride were significantly correlated with the strength of patch test reactivity (r=0.49, P=0.002). By IFN-gamma ELISpot, the average precursor cell frequency reactive to trivalent chromium could be defined as 26, 15, and 11 : 10(6) in volunteers with sensitization and allergy, with sensitization without allergy, and controls, respectively.

Conclusions: In contrast to the patch test, the LTT appears to be a method that is predictive of chromium allergy.