MC-derived particles contain preformed TNF. (A) Differential interference contrast micrograph of purified MC granule particles. (B) SYPRO Ruby–stained SDS-PAGE gel of MC particle-associated proteins. (C) TNF immunoblot of SDS-PAGE–separated proteins from purified particles showing detection of rat TNF. (D) A still image from Video 2 showing that particles released from RBL-2H3 cells after activation retain overexpressed TNF-GFP fusion protein. Bars, 15 µm. White boxes highlight released particles with retained fluorescence. All panels depict data representative of experiments performed more than three times, with trials using lavage from individual rats or pooled from multiple rats, for a total n > 3.