UC Irvine

Human lymphoid cells, when stimulated in vitro with Con-A† or PHA-P, release a group of cytolytically active molecules, termed lymphotoxins (LT). These can be physically separated into various classes and sub-classes by means of molecular sieving columns and ion exchange resins. These studies examine whether these molecules contain carbohydrate. The use of lectin-Sepharose affinity chromatography reveals that human LT molecules in the unfractionated supernatant, and in separated classes and sub-classes, contain at least six different heterogeneously distributed saccharide units. We find that some of the charge heterogeneity associated with α2 sub-class of these molecules appears to be due to the presence of sialic acid, since neuraminidase treatment alters the charge on approximately 20% of this material by ion-exchange analysis. However, this enzyme treatment has no effect on the antigenicity of these molecules. In addition, the carbohydrate moieties do not appear to be necessary for the in vitro lytic activity measured on L-929 cells, since removal with neuraminidase or the presence of saccharides in the lytic reaction has no effect. These studies indicate that LT molecules are glycoproteins. © 1979.