EXOCYTOSIS AND MACROPHAGE-MEDIATED ANTIBODY-DEPENDENT CELLULAR CYTO-TOXICITY - A CAUTIONARY NOTE

  • 1 January 1984
    • journal article
    • research article
    • Vol. 51  (3) , 535-540
Abstract
The appearance of soluble radioisotope from macrophages (M.vphi.) that previously had ingested 51Cr-labeled antibody-coated sheep erythrocytes (51Cr-EA) was assessed to determine if exocytosis contributed to the pool of radioactivity used to measure antibody-dependent cellular cytotoxicity (ADCC). M.vphi. preloaded for 60 min with 51Cr-EA lost the majority of the ingested 51Cr over a subsequent 3 h incubation period. The exocytotic rate was independent of the number of 51Cr-EA ingested, but was temperature-dependent with no appreciable release of 51Cr observed at 4.degree.. The exocytoxic process was unaffected by sodium azide (10 mM) but was markedly enhanced in the presence of iodoacetate (50 mM), cytochalasin B (20 .mu.g/ml) or lidocaine (0.5 mM). M.vphi. rapidly digest engulfed target cells and exocytosis can contribute sufficient soluble radioactivity to the extracellular pool to lead to misinterpretation of putative ADCC activity.

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