Murine autoantibodies to a cryptic membrane antigen: possible explanation for neuraminidase induced increase in cell immunogenicity

The normal sera of several mouse strains contained cytotoxic activity toward lymphocytes treated with neuraminidase (Nase) but not to untreated cells. The greatest cytotoxic activity was in C3H/HeJ mice. CBA/J and AKR/J mice also had high levels. In C57BL/6J mice, there was no cytotoxic activity toward Nase treated lymphocytes. This cytotoxic activity (probably antibody) was complement dependent and stable at 56°C for 30 min, but was inactivated by heating to 80°C for 30 min. Nase treated C3H/HeJ and C57BL/6J cells contained equal amounts of this 'hidden' antigen, as determined by absorption studies. Untreated cells contained no detectable antigen. These natural antibodies to a 'cryptic' antigen exposed by Nase treatment were the basis of a theory to explain the increased immunogenicity of Nase treated cells.