The role of lymph node sinus macrophages in host defense

Strategically positioned along lymphatic vessels, lymph nodes act as filter stations preventing systemic pathogen dissemination; they are primary sites of innate immune responses and provide the staging grounds for the generation of adaptive immunity. Critical mediators of these lymph node functions are two phenotypically and functionally distinct subsets of macrophages: the subcapsular sinus macrophages and the medullary macrophages. This review focuses on the phenotype and function of these lymph node sinus-resident macrophages and summarizes methods for their proper identification and experimental manipulation.