Influence of oral prednisone on patch-test reactions to Rhus antigen

Cost‐effective post‐exposure prevention of poison ivy dermatitis

“…Other studies have shown that subjects experience a reaction to rhus purified antigen at a 1/4000 dilution. 7–10 Such reports have an advantage in the exact quantification of the dose administered; however, extracts have altered potency and can induce dermatitis when contact with poison ivy leaves may not 2,7 . These forms of bioengineering techniques require a constant environment for maximum efficacy, and various factors may modify the results.…”

“…Using a template, four 2.5‐cm squares spaced linearly 2.5 cm apart were marked on each volunteer’s midline supine forearm (a common testing location in studies). 7–10 For all subjects, one bottle of precrushed poison ivy leaves was used that was stored appropriately 7,8 . The minutest traces of sap will cause dermatitis.…”

Is the variability of nickel patch test reactivity over time associated with fluctuations in the systemic T-cell reactivity to nickel?

“…Considering that T‐cell reactivity to Ni is a prerequisite for Ni allergy and patch test reactivity, it is thus possible that fluctuations in the systemic reactivity are of vital importance for the variation in the patch test but that other factors override that effect in certain individuals. Such factors could be differences in the ovulatory phase of the menstrual cycle, 13,21 medication, 22 enhancement of Ni penetration due to impairment of the skin barrier 23 and ultraviolet radiation exposure 24…”

Guidelines for care of contact dermatitis

“…However, if a patient applies potent topical steroids to the back up to 2 days prior to the test being applied 32–34 ( Quality of evidence I ) or is taking oral corticosteroids or immunosuppressant drugs, then there is a significant risk of false negative results. It has been claimed that patch testing is reliable with doses of prednisolone up to 20 mg per day but that figure is based on poison ivy allergy, which causes strongly positive patch tests 35 ( Quality of evidence II.iii ). The effect of systemic steroids on weaker reactions has not been assessed but clinical experience would suggest that if the daily dose is no higher than 10 mg prednisolone, suppression of positive patch tests is unlikely.…”