Tingible body macrophage

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).^[2] Tingible body macrophages contain condensed chromatin fragments.^[3]

A tingible body macrophage.

Follicular cervicitis, H&E stain, with typical features, including tingible-body macrophages.^[1]

TBMs are licensed (empowered) for phagocytosis by follicular dendritic cells (FDCs).^[4] FDCs provide TBMs with MFGE8 protein, which is a phosphatidylserine-binding "eat me" signal for removal of apoptotic germinal center B cells.^[4]

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.^[5]

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.