Preferential reactivity of autoantibodies in murine lupus NZB mice to neuraminidase-treated monosialogangliosides on B cells of mouse spleen.

When analyzed by flow cytometry, reactivity of IgM autoantibodies in sera from NZB mice to spleen B cells, but not to T cells, from BALB/c mice was remarkably increased after treatment of the cells with Vibrio cholerae neuraminidase. By TLC immunostaining with the antibodies, neither neutral nor acidic glycosphingolipids from both BALB/c and NZB mouse spleens were found to be reactive, but after neuraminidase treatment of the TLC plate, prior to the immunostaining, three components became reactive. All of the reactive glycosphingolipids were found to carry a single sialic acid residue and were at a concentration less than 1.3% of the total lipid-bound sialic acids. Their mobilities on TLC plate were close to those of IV3 NeuAcnLc4Cer, IV3 NeuAcII3 NeuAcGg4Cer, and IV3 NeuAcII3 NeuAc2Gg4Cer. In addition, the monosialogangliosides, which became reactive with the autoantibodies after neuraminidase treatment, were found to be predominantly distributed on B cells from BALB/c mice spleen, but not on T cells by TLC immunostaining. These studies demonstrate that the majority of IgM autoantibodies to spleen lymphocytes in sera from NZB mice might react preferentially to terminal sugar residues of three new glycosphingolipids masked by a single sialic acid on B cells, but not on T cells.