Single-cell transcriptomics of granulocytes in asthma and atopic diseases.

Since their early association with atopic disease, granulocytes, particularly eosinophils, have been widely used as biomarkers, yet the mechanisms underlying their role in airway and atopic inflammatory diseases remain incompletely understood. Single-cell transcriptomic approaches have begun to reveal substantial phenotypical and functional heterogeneity among granulocytes such as neutrophils and eosinophils, as well as in mast cells. In contrast, basophils remain sparsely represented in current datasets. As studies of other immune lineages have shown the significance of cellular diversity in atopic disease, extending this resolution to granulocytes marks an important frontier. In this review, we outline the historical and technical challenges that have constrained single-cell studies of human granulocytes and highlight the methodological breakthroughs that are now overcoming these barriers. We systematically reviewed published granulocyte scRNA-seq studies using PubMed and Talk2Data (BioTuring) platform. Our review underscores emerging roles for granulocyte heterogeneity in asthma and atopic disease and identifies remaining knowledge gaps where experimental and computational advances may accelerate understanding of their pathophysiologic functions.