Factors affecting surface expression of glycolipids: influence of lipid environment and ceramide composition on antibody recognition of cerebroside sulfate in liposomes

Abstract

The reactivity of the acidic glycolipid cerebroside sulfate (CBS) with antibody was studied as a function of its lipid environment in vesicles and of its ceramide composition. The lipid environment was varied by using phosphatidylcholine of varying chain length with cholesterol in a phosphatidylcholine:cholesterol:cerebroside sulfate molar ratio to glycolipid of 1:0.75:0.1. The ceramide structure of CBS was varied by using synthetic forms containing palmitic acid, lignoceric acid, or the corresponding alpha-hydroxy fatty acids. Reactivity with antibody was determined by measuring complement-mediated lysis of the vesicles containing a spin-label marker, tempocholine chloride. The data were analyzed by a theoretical model which gives relative values for the dissociation constant and concentration of antibodies within the antiserum which are able to bind to the glycolipid. If the phosphatidylcholine chain length was increased, increasing the bilayer thickness, only a small population of high-affinity antibodies were able to bind to cerebroside sulfate, suggesting decreased surface exposure of the glycosyl head group. A larger population of lower affinity antibodies were able to bind to it in a shorter chain length phosphatidylcholine environment. However, if the chain length of the cerebroside sulfate was increased, it could be recognized by more antibodies of lower affinity than the short chain length form, suggesting that an increase in chain length of the glycolipid increased surface exposure. Hydroxylation of the fatty acid inhibited antibody binding; only a smaller population of higher affinity antibodies was able to bind to the hydroxy fatty acid forms.(ABSTRACT TRUNCATED AT 250 WORDS)

Mycobacterial Di-O-Acyl-Trehalose Inhibits Mitogen- and Antigen-Induced Proliferation of Murine T Cells In Vitro

“…These authors found that the shorter the fatty acyl chain in these glycosphingolipids, the stronger their immunomodulatory effect. In contrast, lipid structural variations seem not to be involved in antigenic recognition of DAT (44), as is the case for some glycosphingolipids (10,32).…”

Studies on the binding of bacteria to glycolipids Two species of Propionibacterium apparently recognize separate epitopes on lactose of lactosylceramide

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A Major Fraction of Glycosphingolipids in Model and Cellular Cholesterol-containing Membranes Is Undetectable by Their Binding Proteins

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