Antigen-presenting function of rat hepatic stellate cells

Introduction: Human and mice hepatic stellate cells (HSCs) are professional antigen-presenting cells (APCs) because they express factors such as MHC-II and co-stimulatory molecules on their surface. They can enhance homeostatic proliferation of natural killer-T cells localized in the liver through the expression of Interleukin–15 (IL–15). Recently, it was demonstrated that HSCs present peptides to CD8+ and CD4+ T cells and mediate cross-priming of CD8+ T cells [Winau et al., submitted]. Aim: The present study aims to analyse the regulation and expression pattern of the surface molecules MHC-I, MHC-II, and CD1d during the transdifferation in rat HSCs. In addition, we analysed the expression of IL–15, a critical stimulator of cellular proliferation, in this hepatic cell type. Methods: Characterization of the gene expression profile and quantification of MHC-I, MHC-II, CD1d and IL–15 by RT-PCR, PCR and DNA-sequencing in rat HSCs. Immunofluorescence via FITC-labelled antibody for detection of mentioned proteins. Results: Immunofluorescence via FITC-labelled antibody revealed that MHC-I, MHC-II, CD1d and IL–15 are expressed in rat HSCs. The corresponding mRNAs were detected by RT-PCR, quatitative PCR and verified by DNA-sequencing. Conclusion/Further studies: We here present data demonstrating that HSC from rat have APC functionality. Necessary components (MHC-I, MHC-II, CD1d, IL–15) involved in this immunological reaction are expressed at mRNA and protein level. Further studies are aimed at the detailed cellular properties (e. g. phagocytotic processes, antigen processing, and presentation) that are involved in the presenting of antigenic peptides and the measurement of the T-cell proliferation induced.