Allergic inflammation in the skin may set the stage for life-threatening reactions elsewhere in the body through a previously unrecognized immune pathway, according to a study by researchers at Tokyo University of Science and Kyoto University in Japan. The work identifies a specialized population of dendritic cells as the crucial link between atopic dermatitis and systemic allergic responses, offering a molecular explanation for the progression known as the “atopic march.”
The atopic march describes the tendency for allergic diseases to develop sequentially, often beginning with atopic dermatitis in infancy and later expanding to food allergies, asthma, or other immune-mediated conditions. In affected individuals, a weakened skin barrier allows environmental or food allergens to penetrate the tissue. The immune system can then become sensitized, producing antibodies that cause exaggerated reactions when the allergen is encountered again. In severe cases, this sensitization can culminate in anaphylaxis, a rapid and potentially fatal systemic response.
Although scientists have long known that type 2 immune signals contribute to allergic disease, the precise mechanism connecting inflammation in the skin with antibody production in distant organs has remained unclear. The new study, published in the Proceedings of the National Academy of Sciences, points to interleukin-13, or IL-13, as a central coordinator. Rather than acting directly on antibody-producing B cells, IL-13 appears to “license” a subset of dendritic cells, enabling them to initiate the immune reactions required for the formation of particularly potent IgE antibodies.
Dendritic cells are immune sentinels that capture foreign material and present fragments of it to T cells, thereby directing the development of adaptive immune responses. The researchers focused on type 2 conventional dendritic cells, known as cDC2. In a mouse model designed to mimic cutaneous allergen sensitization, repeated exposure of the skin to an allergen caused cDC2 cells to acquire enhanced antigen-presenting capabilities under the influence of IL-13. This conditioning allowed the cells to promote a strong antibody response when the animals later encountered an allergen.
The investigators found that the relevant cDC2 population carried several distinguishing surface proteins, including IL13RA1, CX3CR1, and CD301b. IL13RA1 enables cells to respond to IL-13, while CX3CR1 functions as a receptor for fractalkine, a signaling molecule involved in cell migration. The combination of these markers identified cDC2 cells that could not only process and present allergen-derived material but also move beyond the skin and circulate through the bloodstream.
According to the study, CX3CR1-positive cDC2 cells transport allergen information to secondary lymphoid organs, including the spleen. These organs are major sites of immune-cell interaction and antibody production. Once there, the licensed dendritic cells help coordinate T-cell and B-cell responses that generate high-affinity IgE antibodies. IgE binds to receptors on mast cells and basophils, preparing them to release histamine and other inflammatory mediators when the allergen is encountered again. A widespread release of these mediators can produce the drop in blood pressure, airway narrowing, swelling, and other symptoms associated with anaphylaxis.
The importance of cDC2 migration became clear when the researchers used a drug to block CX3CR1. Preventing signaling through this receptor substantially impaired the movement of the dendritic cells and sharply reduced the production of high-affinity IgE in the mice. The result suggests that the journey of allergen-bearing cDC2 cells from inflamed skin to immune organs is not incidental but an essential step in the transition from localized dermatitis to systemic allergic sensitization.
The team also examined human samples to determine whether the pathway observed in mice might be relevant to patients. Skin samples from individuals with atopic dermatitis contained increased numbers of cDC2 cells expressing IL13RA1 and CX3CR1. Similar cells were also more abundant in blood samples from people with allergic diseases. Their numbers correlated with IgE concentrations, providing evidence that the IL-13–cDC2–CX3CR1 circuit may operate in human allergic conditions as well as in the experimental model.
The findings refine the current understanding of how type 2 cytokines regulate allergy. IL-4 is already known to act directly on B cells and promote class switching toward IgE production. IL-13, by contrast, appears to influence the same outcome indirectly by changing the behavior of cDC2 cells and strengthening their ability to organize antigen-specific immunity. This distinction may help explain why medicines that block IL-13, including tralokinumab and lebrikizumab, can reduce inflammation in atopic dermatitis and may interrupt signals that connect skin disease with broader allergic sensitization.
The researchers say that targeting CX3CR1 or preventing IL-13-dependent licensing of cDC2 cells could provide additional strategies for disrupting the atopic march. However, the findings remain primarily mechanistic and experimental, and further research will be needed to determine whether blocking this pathway can safely prevent food allergy, asthma, or anaphylaxis in patients. As allergic diseases continue to rise worldwide, the discovery offers a new framework for understanding how a damaged skin barrier can influence immune responses throughout the body and identifies a cellular route that future therapies may be able to interrupt.
Subject of Research: Animals
Article Title: IL-13 signaling in cDC2 is required for systemic anaphylactic responses
News Publication Date: 9-Jul-2026
Web References: https://doi.org/10.1073/pnas.2608478123; https://doi.org/10.1002/dni2.70014
References: Proceedings of the National Academy of Sciences, “IL-13 signaling in cDC2 is required for systemic anaphylactic responses,” DOI: 10.1073/pnas.2608478123. Barrier Immunity, “A Role of the IL-13 Signal and Type 2 Conventional Dendritic Cell in the Atopic March,” DOI: 10.1002/dni2.70014
Image Credits: Professor Emeritus Masato Kubo, Tokyo University of Science
Keywords: atopic march, atopic dermatitis, allergy, anaphylaxis, IL-13, cDC2, dendritic cells, CX3CR1, IgE, immune response, skin inflammation, asthma, food allergy
