Dissociation of allergenic and immunogenic functions in contact sensitivity to para-phenylenediamine.
Contact sensitivity to para-phenylenediamine (PPD) is a frequent delayed-type hypersensitivity resulting in contact dermatitis. The aim of the present study, conducted in 16 patients allergic to PPD (as assessed by a positive patch test), was to get better insight into the mechanism of T-cell activation in PPD contact sensitivity. PPD was unable to induce significant proliferation of T cells from a first set of 9 patients. In 7 further patients, lymphocyte proliferation was assessed using PPD and 2 PPD metabolites, namely Brandrowski's base (BB) and benzoquinone (BQ). BB specifically stimulated T-cell proliferation in a dose-dependent fashion in all 7 patients whereas BQ, like PPD, was ineffective. The peripheral blood mononuclear cells (PBMC) of 8 PPD nonallergic individuals did not respond to either PPD, BB or BQ. We concluded from this study that: (1) the immunogenic hapten in PPD hypersensitivity is not PPD itself, and (2) BB might be the oxidative derivative of PPD endowed with T-cell-activating properties. Further support to this statement was provided by the observation that a T cell line derived from PBMC of a PPD-allergic patient in the presence of PPD responded to BB but not to PPD. Our in vitro results suggest that PPD is a prohapten which when applied on the skin is metabolized and converted into products (such as BB) which are the immunogenic haptens able to activate specific T cells.
Krasteva
M
M
INSERM U346, Université Claude-Bernard Lyon I, Hôpital Edouard-Herriot, France.
Nicolas
J F
JF
Chabeau
G
G
Garrigue
J L
JL
Bour
H
H
Thivolet
J
J
Schmitt
D
D
D016227:Benzoquinones / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D017449:Dermatitis, Allergic Contact / Q000276:immunology*; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D010655:Phenylenediamines / Q000276:immunology*; D012882:Skin Tests; D013601:T-Lymphocytes / Q000276:immunology*
D016227:Benzoquinones; D010655:Phenylenediamines; C051597:Bandrowski's base; C004532:quinone