Severe asthma is characterized by a sex-specific ILC landscape and aberrant airway profile that is suppressed by anti-IL-5/5Rα biologics.

Innate lymphoid cells (ILCs) fulfill critical roles in maintenance of tissue-specific homeostasis but have also been implicated in disease pathology when dysregulated. Although they are broadly classified into three core subsets, it is increasingly apparent that ILCs exhibit plasticity in response to microenvironmental factors. Accurate and holistic evaluation of the ILC landscape is critical to understanding the contribution of ILCs to disease pathology. Using high-parameter flow cytometry, we comprehensively interrogated the phenotypic and functional diversity of ILCs in healthy volunteers and patients with severe asthma (SA), assessing the reciprocity between peripheral blood and airway compartments and dissecting the impact of anti-IL-5/5Rα biologics on these responses. We identified substantial heterogeneity and putative plasticity in human ILC responses, highlighting inherent limitations of conventional enumeration strategies. Deep phenotypic and functional profiling demonstrated a distinct sexual dimorphism in ILC responses in patients with SA. Females displayed an elevated abundance of circulating ILC progenitors, ILC1s, and ILC3s, whereas males presented with diminished ILC2s compared with respective healthy controls. Circulating ILC progenitors inversely correlated with testosterone concentrations. Moreover, we identified a reciprocal influx of all core ILC subsets into the airways of patients with SA, with unbiased multisource clustering identifying a relationship between elevated airway ILC2s and reduced lung function. Last, we showed that anti-IL-5/5Rα biologics largely ablated airway ILC type 2 cytokine production without affecting core ILC subset abundance in the peripheral blood or airways, identifying a potential mechanism whereby anti-IL-5/5Rα biologics alleviate clinical disease in patients with SA.