A tingible body macrophage (TBM) is a type of macrophage predominantly found in germinal centers of lymph nodes. They contain many phagocytized, apoptotic cells in various states of degradation, referred to as tingible bodies (tingible meaning stainable).[1] Tingible body macrophages contain condensed chromatin fragments.[2]
TBMs are licensed (empowered) for phagocytosis by follicular dendritic cells (FDCs).[3] FDCs provide TBMs with MFGE8 protein, which is a phosphatidylserine-binding "eat me" signal for removal of apoptotic germinal center B cells.
It is thought that they may play a role in downregulating the germinal center reaction by the release of prostaglandins and hence a reduced B-cell induction of IL-2.[4]
Macrophages that contain debris from ingested lymphocytes are characteristic of a reactive follicular center in benign reactive lymphadenitis. Other accompanying signs of a benign follicular hyperplasia are well developed germinal centers with dark and light zones, in addition to numerous mitotic figures.