Tumor-associated
glycosphingolipids are a common finding in human
tumors, and
monoclonal antibodies directed to defined
carbohydrate epitopes of these structures have been developed. A majority of the
glycosphingolipid antigens are of the lacto series, types 1 and 2, and these
epitopes are often also found on
glycoproteins. The
tumor-associated
gangliosides of the ganglio series, preferentially found in
tumors of neuroectodermal origin, have binding
epitopes that have not been detected in
glycoproteins. A large number of
monoclonal antibodies, mainly murine but some human, have been produced, and their
epitope specificity defined. These
antibodies have been used for investigation of the role of
tumor-associated
glycosphingolipids in
tumor cells. Some
antibodies have been shown to inhibit the growth of tumor cell lines in vitro and in vivo and to influence the adhesion properties of
tumor cells, and some
antibodies have been shown to give a clinical response. Tumor cell lines are commonly used in
tumor biology studies, but the expression of
tumor-associated
glycosphingolipids in tumor cell lines does not always reflect their expression in the
tumor tissue from which the cell line originates. The expression of
tumor-associated
glycosphingolipids has also been shown to be different in cells grown in vitro or as solid
tumors in nude mice or rats. In conclusion,
monoclonal antibodies specific for
tumor-associated
glycosphingolipids may be valuable tools in diagnosis and, in addition, in
therapy,
glycosphingolipids may also be used in active immunotherapy. The availability of these
antibodies also opens the possibility of studying the
biological function of
glycosphingolipids and may then lead to new approaches for the improved diagnosis and
therapy of human
tumors.