Differential susceptibility between skin and vaginal mucosa in sensitization phase of allergic contact dermatitis in mice

Abstract

Introduction: Mechanisms underlying skin sensitization in allergic contact dermatitis have been actively studied using the murine contact hypersensitivity (CHS) model. However, much less is known about sensitization at the vaginal mucosa (VM).

Methods: We developed a CHS model with VM sensitization and epicutaneous elicitation at the ear. We then examined the proliferation activity of lymphocytes, the frequencies of T cells and the differentiation of hapten-specific T cells in draining lymph nodes (dLNs) after sensitization.

Results: Hapten-specific CHS responses to 2,4-dinitrofluorobenzene (DNFB), 2,4,6-trinitrochrolobenzene, and oxazolone assessed by ear swelling suggested that the VM would be an inductive site of CHS to haptens. In the comparisons of CHS responses to each of the three haptens examined, the lower responses in VM-sensitized mice were observed than skin-sensitized mice (e.g., DNFB-induced responses, -56%; p < .001, at 48 h after challenge). Consistent with the CHS responses, the DNFB-induced proliferation of cells in dLNs examined by 5-bromo-2'-deoxyuridine assay was lower (-62%; p < .001) in VM-sensitized mice than skin-sensitized mice. On the other hand, between skin and VM sensitization, no significant differences were observed in the frequencies of interferon-γ-producing CD4⁺ and CD8⁺ effector, and regulatory T cells in dLNs after sensitization. We also observed no significant differences with respect to differentiation of hapten-specific T cells based on the examination of cytokine production from dLN cells stimulated in vitro with 2,4-dinitrobenzene sulfonate.

Conclusion: These findings suggested that the lower T cell proliferation after VM sensitization is important for the lower CHS responses with VM sensitization than skin sensitization.

Keywords: allergic contact dermatitis; contact hypersensitivity; draining lymph node cell; skin; vaginal mucosa.