About the Cover
The Journal of Experimental Medicine
195
10
The hypothesis that Fas ligand (FasL) expression in tumor cells may impair the in vivo efficacy of antitumor immune responses has been debated. The cover shows the presence of FasL in well-defined vesicles (FasL staining in red) within the cytoplasm of human melanoma cells. FasL colocalizes with both melanosomal and lysosomal antigens. Isolated melanosomes containing FasL exert Fas-mediated apoptosis of Jurkat cells. Melanosome-containing multivesicular bodies degranulate extracellularly and release FasL-bearing microvesicles that are able to trigger Fas-mediated apoptosis in lymphocytes, suggesting a potential mechanism whereby tumor counterattack is mediated through the secretion of subcellular particles expressing functional FasL. See related article by Andreola et al., pp.
1303-1316.
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