Production of B cell differentiation factors by mouse parenchymal liver cells

Previously we reported that most antibody secreting cells secreted IgA in the liver. Here we assessed the possibility that parenchymal liver cells (PLC) produced factors, transforming growth factor (TGF)-beta and IL-5, which participate in the differentiation of B cells to IgA-secreting cells. We showed that TGF-beta activity was present in the culture supernatant of PLC, and IL-5 activity was in the lysate of PLC. Moreover, it was confirmed that IL-5 protein produced by PLC was mainly localized in the cell membrane by histochemical staining. The findings that both TGF-beta and IL-5 were produced by PLC should provide useful information concerning the fact that IgA-secreting cells were dominant in the liver.