Nuclear localization of anti-Hu antibody is not associated with in vitro cytotoxicity

IgG fractions of sera containing anti-Hu antibodies or control sera were incubated with Hu-positive and Hu-negative cell lines. Anti-Hu IgG specifically localized in the nucleus of Hu-positive cells. Anti-Hu-positive and control sera were incubated with Hu-positive cells and human complement or peripheral blood mononuclear cells. Hu antibody caused neither complement-mediated lysis nor augmented antibody-dependent cell-mediated cytotoxicity. Anti-Hu IgG did not affect proliferation of Hu-positive cells. Anti-Hu antibodies may not play a direct role in tissue injury in patients with paraneoplastic encephalomyeloneuropathy and anti-Hu antibodies.