ILC homeostasis phenotyping in various tissues, aging, and sex differences

Innate lymphoid cells are the innate counterpart to CD4+ T cells that are mediated by the same transcription factors and produce similar cytokines. ILCs are being investigated in many different disease states, but the field current lacks foundational information on ILC representation whether it be in tissues, between males and females, or in aging as these are all vital components in disease etiology and severity. Our descriptive study used flow cytometry to characterize ILCs compared to the entire CD45+ (e.g., lymphocyte) and lineage negative (e.g., ILC) compartments to understand their homeostatic balance and plasticity. Moreover, we defined ILC2 expression and subsets based on their cytokine production and created several mathematical models to elucidate the correlation of extra- and intra-cellular ILC2 markers from least to most complex. ILC studies would benefit from more unbiased, holistic experiments including RNA-seq and mass spectroscopy to further define ILCs in steady state before adding more complex pathways like different disease states to enhance translational value and therapeutic targeting of these cells.