Dendritic cell recognition by group 3 innate lymphoid cells through DNAX accessory molecule 1 triggers proinflammatory reciprocal cell activation

• Published in: Journal of allergy and clinical immunology 2019-10, Vol.144 (4), p.1118-1122.e6
• Main Authors: Campana, Stefania, Di Carlo, Emma, De Pasquale, Claudia, Barberi, Chiara, Oliveri, Daniela, Migliore, Giacomo Sidoti, Cannavò, Serafinella Patrizia, Galletti, Bruno, Pende, Daniela, Carrega, Paolo, Ferlazzo, Guido
• Format: Article
• Language: English
• Subjects: Antigen-presenting cells; Cell activation; Cell culture; Cell proliferation; Cell recognition; Cytokines; Dendritic cells; Dermis; IL-1β; Immune response; Inflammation; Interleukin 22; Lymphocytes B; Lymphoid cells; Neutrophilia; Peripheral blood; Skin; Statistical analysis; Tonsil
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2019.06.008

[...]the frequency of NKp44+ ILC3s in human inflamed tonsils apparently correlated with the degree of inflammation and in vitro appeared to be the prominent ILC subset activated by DCs (see Fig E1, B-E). [...]in the context of the early phase of the immune response, the role played by ILC3s in activating the subsequent adaptive response might be more relevant than previously appreciated, particularly in settings in which activation of DCs by pathogen/danger signals might be inefficient, including cancer. In this context, it is worth mentioning that IL-22 production is mainly restricted to ILC3s expressing NKp44, a subset not detectable in the peripheral blood of healthy subjects8 but considerably accumulated and activated following interaction with DCs. [...]in support of the model proposed here, the inflamed papillary dermis of psoriatic skin reveals a massive presence of both IL-1β–producing DCs and ILC3s (Fig 2, F). P values of less than .05 were considered statistically significant.Results Frequency of ILC3s increases upon culture with DCs and is associated with tonsillar inflammation In human tonsils ILC3s represent the most prominent subset among CD127hi ILCs, accounting for about 6 × 105 ± 5 × 104 cells per tonsil, whereas ILC2s are barely detectable (Fig E1, A).E2 Within the ILC3 population, ILC3s that express NKp44 represent the most abundant subset (Fig E1, A), and interestingly, we observed that their amount correlated with total peripheral blood leukocyte counts, with neutrophilia, as well as in the tonsils, with both the frequency of B cells and the percentage of proliferating B cells within the tonsils (Fig E1, B). Because of this apparent association between inflamed tonsillar reactivity and the frequency of NKp44+ ILC3s, we hypothesized that accessory cells, such as DCs, might play a role in ILC3 activation, proliferation, or both.