concanavalin-a and Hepatitis-A

Kupffer cells (KCs) are liver resident macrophages which are important for tissue homeostasis and have been implicated in immunogenic, tolerogenic and pathogenic immune reactions depending on the insult. These cells and the biomarkers they express thus represent interesting in vivo sensors for monitoring liver inflammation. In the current study, we explored whether KCs can be monitored non-invasively using single-photon-emission computed tomography (SPECT) with (99m)Tc labeled nanobodies (Nbs) targeting selected biomarkers. Nbs targeting V-set and immunoglobulin domain-containing 4 (Vsig4) or macrophage mannose receptor (MMR) accumulated in the liver of untreated mice. The liver targeting of anti-Vsig4 Nbs, but not anti-MMR Nbs, was blunted upon depletion of macrophages, highlighting specificity of anti-Vsig4 Nbs for liver macrophage imaging. Ex vivo flow cytometry and immunohistochemistry analysis confirmed that anti-Vsig4 Nbs specifically targeted KCs but no other cell types in the liver. Upon induction of acute hepatitis using concanavalin A (ConA), down-regulation of the in vivo imaging signal obtained using anti-Vsig4 Nbs reflected reduction in KC numbers and transient modulation of Vsig4 expression on KCs. Overall, these results indicate that Nbs targeting Vsig4 as molecular imaging biomarker enable non-invasive monitoring of KCs during hepatic inflammation.

Topics: Acute Disease; Animals; Antigens; Antigens, Surface; CD11b Antigen; Cell Count; Concanavalin A; Cytokines; Disease Models, Animal; Gene Expression; Hepatitis A; Immunophenotyping; Kupffer Cells; Male; Mice; Molecular Imaging; Phenotype; Receptors, Complement; Single-Domain Antibodies

The course of viral hepatitis is markedly influenced by the immunologic response to the infective agent. The immune defense of viral diseases is specially connected to an intact function of T lymphocytes. Investigation of T cell function during acute and chronic viral hepatitis showed an altered immune response, recognizable from the relative number of T lymphocytes, the affinity and ability of lymphocytes to be stimulated by phytohemagglutinin and the demonstration of in vivo activated lymphocytes. Although the interpretation of some of these findings is still difficult, the study of the various cellular immune reactions permits a better understanding of the pathogenesis and course of viral hepatitis.

Topics: Acute Disease; Autoantigens; B-Lymphocytes; Chronic Disease; Concanavalin A; Hepatitis A; Hepatitis B Antigens; Humans; Immunity, Cellular; Immunization; Lectins; Liver; Lymphocyte Activation; Macrophage Migration-Inhibitory Factors; T-Lymphocytes

Topics: Carrier State; Chromatography, Gel; Concanavalin A; Epitopes; Hepatitis A; Hepatitis B Antigens; Humans; Isoelectric Focusing; Methods; Microscopy, Electron