CD8+ memory T cells present in tissues mobilize neutrophils essential for contact dermatitis flare-ups

First published: June 25, 2021 https://doi.org/10.1111/all.14986

Commentary

Allergic contact dermatitis (ACD) has been described as a delayed-type hypersensitivity reaction, but in fact it has been observed that itchy erythema, edema, occurs within hours of re-exposure to the specific contact allergen to which one was previously sensitized.

Recent studies have shown that memory T (T RM) cells present in the skin play a central role in ACD, but the pathogenic role of T RM cells during allergen-induced flare-ups is not known.

The study investigated the role of epidermal TRM cells in the flare-up response to the experimental contact allergen 1-fluoro-2,4-dinitrobenzene (DNFB) using various mouse models and cell depletion protocols.

Results show that CD8 + T RM cells initiate a massive infiltration of neutrophils into the epidermis within 12 hours after re-exposure to the contact allergen. Depletion of neutrophils prior to re-exposure to the allergen abrogated the flare-up response. Furthermore, we show that CD8 + T RM cells mediate neutrophil mobilization by inducing the production of CXCL1 and CXCL2 in the skin, and that blockade of CXC chemokine receptor types 1 and 2 inhibits the flare-up response and neutrophil infiltration.

From this study, we showed that epidermal CD8 + T RM cells trigger ACD flare-ups by rapid neutrophil mobilization into the epidermis.