Imaging the immune system redux.

Many of the reviews include discussion of diffusible molecules involved in cell-cell communication during the evolution of innate and adaptive responses (eg, interferons) and how these mediators influence the outcome of the dynamic processes visualized by optical methods. New data on tissue-resident T cells also fall in this category, as do recent observations of perivascular co-localization of effector lymphocytes and presenting cells at sites of effector function within tissues. Technologies are now emerging that will permit combining the protein and cell-based optical imaging methods used to date with recent advances in nucleic acid/genomic methods, especially single-cell sequencing. [Extracted from the article]