Abstract

Paragloboside (lacto-N-neotetraosyl ceramide) is a biosynthetic precursor of the ABH and P1 blood group glycosphingolipids and of one class of gangliosides. This study concerns the specificity of rabbit anti-paragloboside antibodies, andtheir reactions with human erythrocytes and lymphocytes. Lacto-N-neotetraose was approximately 10 times as effective as lacto-N-tetraose in inhibiting complement fixation by purified IgG antibodies to paragloboside. The purified antibodies cross-reacted weakly with lactosyl ceramide, asialo GM1, and lacto-N-neotetraosyl polylysine. The purified IgG and IgM antibodies exhibited weak hemagglutinating activity which was enhanced by treatment of erythrocytes with papain or neuraminidase. In contrast to a macroglobulin described by Tsai et al. (J. Immunol. 117:717, 1976), which also binds paragloboside and lacto-N-neotetraose, anti-paragloboside antibodies reacted equally well with normal adult, O1, and umbilical cord erythrocytes. The IgG antibodies to paragloboside reacted with about 60% of B lymphocytes of peripheral blood and 5 to 10% of T cells. The relationship between antibodies to paragloboside and other lectins and antibodies directed against beta-galactosyl groups, including anti-T (Thomsen-Friedenreich) antibodies, is discussed.