Charlotte Devantier Jensen.pmd - Videncenter for Allergi

Fig. 13. Illustration of skin irritation. The top shows subclinical irritation
responses that do not develop into a visible eczema. Below is
illustrated cumulated irritation that results in the development of clinical
eczema.
TRIAL III – INVESTIGATION OF RE-TEST
REACTIVITY BY BOTH PATCH AND USE TEST
WITH MDBGN IN SENSITIZED INDIVIDUALS
Hindsén and co-workers showed in clinical trials that skin with
healed nickel-induced allergic contact dermatitis was re-test
hyperreactive to nickel for several months after the dermatitis
was clinically healed 19,87 . Accordingly, animal studies have
shown increased re-test reactivity to the allergens DNCB and
2-hydroxyethylmethacrylate (HEMA) 88-90 . In this study, we
investigated the re-exposure response of skin with previous
eczema from MDBGN.
17 MDBGN-sensitized subjects participated in this trial. An
area of homogeneous dermatitis was produced on the lower
back of the test patients by exposing a 5×8 cm skin site to
MDBGN (see the Methods section). The dermatitis was at the
least characterized by erythema and infiltration. An example
of experimental eczema on the back of a subject is shown in
Fig 14. As control site, a corresponding area was treated with
vehicle and no skin changes developed from this exposure.
One month later, when the dermatitis had healed, the test
sites were challenged. This was done by patch testing with 6
consecutive dilutions of MDBGN with concentrations within
a range determined according to the sensitivity of the patient
found one month earlier. In Fig. 15 the study design is illustrated.
The scoring system described in Table 7 was used to
get a more detailed patch test reading than with the ICDRG
scoring system 91 . The scores for the 6 patch test reactions were
summed for each test site, resulting in a total score for both
the previously eczematous area and the control area for each
Contact allergy to the preservative methyldibromoglutaronitrile 21
Fig. 14. Example of area of provoked MDBGN-dermatitis on the lower
back of a subject.
patient (Table 8). 11 patients had a higher summed score for
the pre-treated skin site and 4 had the highest summed score
for the normal skin site. Two subjects had equal summed scores
for the two areas. The differences in the summed scores for
the pre-treated area and the area of normal skin are illustrated
for all subjects in Fig. 16, and the highest total score was given
to the formerly eczematous area. A statistically significant dif-
Fig. 15. Diagram of study design.
Forum for Nord Derm Ven Vol. 10, 2005 – Suppl. 8