Morphology and phenotype of peripheral blood ILCs. (A) May-Grünwald-Giemsa staining (original magnification ×100), after cytospin, of human lineage⁻ CD127⁺ CRTH2⁺ ILC2s that were sort-purified from the peripheral blood. (B) Phenotype and gating strategy for ILC1s, ILC2s, and NCR⁻ and NCR⁺ ILC3s derived from tonsil (upper panels) and peripheral blood (lower panels) of healthy humans. The lineage cocktail contains markers for T cells (TCRαβ and TCRγδ), B cells (CD19), NK cells (CD94), myeloid and plasmacytoid dendritic cells (CD1a, CD11c, CD123, and BDCA2), monocytes and macrophages (CD14), mast cells (FcεR1), and stem cells (CD34). In the peripheral blood, NCR⁺ ILC3s are virtually absent in healthy individuals.