Differential expressions of IL-3 and FcRI in the peripheral blood mononuclear cells and lesional skin of patients with extrinsic atopic dermatitis and intrinsic atopic dermatitis

Background: A small subgroup of atopic dermatitis (AD) patients show low total and allergen-specific immunoglobulin (IgE) levels. This subgroup has been termed 'intrinsic' AD (IAD) as compared to its counterpart 'extrinsic' AD (EAD). However, the difference of cytokine expression between IAD and EAD has not been fully understood. Objective: To compare the expression of various inflammatory cytokines in the peripheral blood mononuclear cells (PBMCs) and lesional skin of patients with IAD and EAD, which are known to be associated with AD pathophysiology. Methods: We assessed the protein levels of cytokines in the PBMCs and lesional skin. We evaluated the levels of IL-3, IL-4, IL-5, IL-6, IL-10, IL-13, FcRI and FcRII from the PBMCs and lesional skin of patients with IAD and EAD. Results: The patients with EAD had elevated levels of the IL-3 expression in their PBMCs and elevated levels of FcRI in their lesional skin compared to that of the patients with IAD. The expression of other cytokines did not differ in the PBMCs and lesional skin from the two subgroups. Conclusion: This study suggests that IL-3 could be associated with the pathophysiology of EAD as compared to that of IAD, along with FcRI which was previously shown to be highly expressed in EAD patients.