A growing body of evidence suggests that adipocytes, and the triacylglycerol fatty acids within them, play an important role in supporting the inflammatory immune response. Inflammatory cytokines produced by an activated lymph node cause the release of fatty acids from neighbouring adipocytes, and the fatty acids are taken up into lymph node lymphoid cells, where they can be used as precursors for eicosanoid and plasma membrane synthesis, or as a fuel source. The mechanism of transport of fatty acids from adipocytes across the lymph node capsule and into lymphoid cells remains to be elucidated. Here we present evidence from light and electron microscopy that small fat-filled cells are found within the lymph node, and that 24 hours after an immune challenge they are associated with dendritic cells. The small adipocytes express S100 protein and insulin receptor, characteristics of mature adipocytes. Our observations suggest a mechanism for delivering triacylglycerol fatty acids directly to their site of use in supplying components for an immune response
