@entity379 inhibits the growth and differentiation of highly purified @entity1 erythroid colony-forming cells (ECFCs) and induces erythroblast apoptosis. These effects are dose- and time-dependent. Because the @entity15392 known as Fas ( @entity1197 ; @entity1197 ) triggers programmed cell death after activation by its ligand and because incubation of @entity1 ECFCs with @entity379 produces apoptosis, we have investigated the expression and function of Fas and @entity12 ( @entity12 ) in highly purified @entity1 ECFCs before and after incubation with @entity379 in vitro. Only a small percentage of normal @entity1 ECFCs express Fas and this is present at a low level as detected by Northern blotting for the Fas mRNA and flow cytometric analysis of Fas protein using a specific mouse monoclonal antibody. The addition of @entity379 markedly increased the percentage of cells expressing Fas on the surface of the ECFCs as well as the intensity of Fas expression. Fas mRNA was increased by 6 hours, whereas @entity1197 on the cell surface increased by 24 hours, with a plateau at 72 hours. This increase correlated with the inhibitory effect of @entity379 on ECFC proliferation. @entity10762 anti-Fas antibody, which mimics the action of the natural @entity12 , greatly enhanced @entity379 -mediated suppression of cell growth and production of apoptosis, indicating that Fas is functional. Expression of @entity12 was also demonstrated in normal ECFCs by reverse transcriptase-polymerase chain reaction and flow cytometric analysis with specific monoclonal antibody. @entity12 was constitutively expressed among erythroid progenitors as they matured from day 5 to day 8 and @entity379 treatment did not change this expression. Apoptosis induced by @entity379 was greatly reduced by the NOK-2 antihuman @entity12 antibody and an engineered soluble @entity12 receptor, Fas-Fc, suggesting that Fas- @entity12 interactions among the ECFCs produce the erythroid inhibitory effects and apoptosis initiated by @entity379 .

XXXX is present in @entity1 erythroid colony-forming cells and interacts with Fas induced by interferon gamma to produce erythroid cell apoptosis.

@entity1 :: ('9606', 'Species') :: ['human'] @entity1197 :: ('355', 'Gene') :: ['Fas antigen', 'APO-1', 'CD95'] @entity12 :: ('356', 'Gene') :: ['FasL', 'Fas ligand'] @entity379 :: ('3458', 'Gene') :: ['Interferon gamma (IFNgamma)', 'IFNgamma'] @entity15392 :: ('57126', 'Gene') :: ['cell surface receptor'] @entity10762 :: ('MESH:C418965', 'Chemical') :: ['CH-11']
@entity12 :: (356,Gene) :: ['Fas ligand']
