INTERLEUKIN-4 AND THE INTERLEUKIN-4 RECEPTOR IN ALLERGIC CONTACT-DERMATITIS

Cutaneous immune responses involving T helper (TH) type 1 (TH1) and ty pe 2 (TH2) T cells, characterised by secretion of interferon-gamma (If n-gamma) and interleukin-4 (IL-4), respectively, have both been report ed in allergic contact dermatitis (ACD). We used immunohistochemistry to localize expression of IL-4 in ACD lesions and unaffected skin. Ato pic dermatitis (AD) and psoriasis biopsies provided positive and negat ive IL-4 immunoreactivity controls. To investigate the role of IL-4 in ACD, we investigated expression of IL-4 receptors in ACD AD and psori atic skin. IL-4 immunoreactivity was found in cells in the dermal infi ltrate in 3 out of 7 ACD lesions, but not in unaffected skin from thes e patients. IL-4 immunoreactivity was found in the dermal infiltrate o f all lesional and unaffected AD biopsies, but in none of the psoriati c biopsies. IL-4 receptor alpha chain immunoreactivity, associated wit h dermal mast cells, was found in all patients. Local expression of IL -4 in ACD indicates either TH2 or TH0 immunoregulation in some allergi c contact dermatitis lesions. Our findings do not support exclusive TH 1 or TH2 cutaneous immune responses in ACD. Expression of IL-4 recepto rs by cutaneous mast cells provides a route through which local effect s of IL-4 might be mediated. (C) Munksgaard, 1998.