Human Liver Stem Cells Suppress T-Cell Proliferation, NK Activity, and Dendritic Cell Differentiation

Figure 4

HLA-G expression mediates the HLSC activity on NKs. (a) Representative () cytofluorimetric analysis of HLA-G expression on HLSC membrane and after intracytoplasmic staining, using the specific MEMG/9 antibody (native form for human HLA-G1). (b) Western Blot analyses confirmed the presence of HLA-G in HLSCs at different passages of culture (p4, p6, and p8). (c) Soluble HLA-G is present in HLSC supernatants, as indicated by Western Blot after immune-precipitation with specific antibody. HLA-G protein expression was detected through mAb 4H84, resulting in specific band corresponding to the expected molecular weight of 39 kDa. (d) Representative () cytofluorimetric analysis of CD107a expression on NKs in degranulation assay, after 4 days of incubation with HLSCs in the presence or the absence of specific blocking antibody against HLA-G (87-G). HLSCs, via the secretion of HLA-G reduced NK degranulation, as a specific neutralizing anti-HLA-G antibody restored degranulation activity to levels similar to those following incubation of NKs with K562 cells alone (CD56⁺CD107⁺: 87 ± 5% in NK CTRL, 5.5 ± 4% in NKs cocultured with HLSCs, and 90 ± 5.3% in NKs cocultured with HLSCs in the presence of blocking antibody).

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