FAS LIGAND (FASL, CD95L, APO-1L) EXPRESSION IN MURINE MAST-CELLS

Fas ligand (FasL, CD95L, Apo-1L), a type II membrane protein belonging to the tumour necrosis factor family, induces apoptosis in Fas-bearin g cells. As murine mast cells have been shown to express Fas antigen, we hypothesized that mast cells might also express Fast. To explore th is possibility, we first demonstrated Fast mRNA in mast cells by rever se transcription-polymerase chain reaction and Fast protein by immunob lot analysis. Fast protein was shown to be exclusively located within the cell by flow cytometry. Ln agreement with this observation, bone m arrow cultured mast cells were unable to kill Jurkat T cells. Our resu lts demonstrate that Fast is expressed in murine mast cells and sugges t that this murine mast cell Fast is not lytic, owing to the intracell ular localization.