Figure 2 (Key Figure). Examples of current immune cell-specific drivers and reporter options.

(a) Simplified diagram of hematopoiesis and cell lineages of the mouse immune system. In blue are the drivers that have been used to perform fate-mapping on specific cell types with corresponding references: megakaryocytes [125]; macrophages [2,18-37,63,126]; monocytes [96]; dendritic cells [69]; mast cells [39,86]; natural killer (NK) cells [52,53,95]; ILCs [57,58]; B cells [46-51]; CD4⁺T cells [41,43-45,77,127]; CD8⁺ T cells [40,42,99]; γδ T cells [54,55,89,128]; invariant natural killer T (iNKT) cells [59]. (b) Reporter constructs are usually inserted into a permissive locus. Reporters can be classified into three major types: single reporters, such as those that express a single fluorescent protein or an enzyme; multi reporters, such as those that bicistronically express two proteins [12] or are switchable [13]; and stochastic reporters in which recombination leads to random expression of a fluorescent marker (confetti) [14] or a genetic barcode (polylox) [15,16].