Contact hypersensitivity machinery (CHS)

The contact hypersensitivity (CHS) machinery represents the integrated cellular and molecular pathway responsible for Type IV delayed-type hypersensitivity reactions, most commonly manifesting as allergic contact dermatitis [1]. This process begins with the sensitization phase, where low-molecular-weight haptens penetrate the stratum corneum and conjugate with skin proteins to form complete antigens [2]. These antigens are captured by professional antigen-presenting cells, such as Langerhans cells and dermal dendritic cells, which then migrate to draining lymph nodes to prime hapten-specific CD4+ and CD8+ T-cells [3]. Upon subsequent challenge with the same hapten, these sensitized T-cells are recruited to the skin, where they release pro-inflammatory cytokines including interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and interleukin-17 (IL-17) [2, 4]. This orchestrated response leads to the recruitment of other inflammatory cells, resulting in the characteristic redness, swelling, and pruritus associated with the condition [1]. Pharmacological management of this machinery typically targets specific components, such as calcineurin inhibitors to block T-cell activation or JAK inhibitors to interrupt cytokine signaling [1, 3].

Other names

Allergic contact dermatitis pathwayType IV hypersensitivityDelayed-type hypersensitivityContact sensitization machinery

Inhibition of T-cell activation, blockade of cytokine signaling (e.g., JAK/STAT pathway), and suppression of inflammatory mediator release.