The
carbohydrate antigen termed Lex (Gal beta 1----4[Fuc alpha 1----3]GlcNAc beta 1----R), its di- or trimeric form, and their sialylated
antigens have been characterized as developmentally regulated,
tumor-associated
antigens in human gastrointestinal epithelia. In this paper, remarkable changes of these
antigens, defined by respective
monoclonal antibodies FH3, FH4, and FH6, in fetal kidney (mesonephros and metanephros) and other urogenital organs, as well as in various types of kidney
tumors, have been investigated. During the development of each organ and tissue, the
antigens were found to be maximally expressed at a defined period of organogenesis, and a shifting of expression from one locus to another was observed. Each
antigen showed a slightly but clearly different stage of maximum expression. The following changes in metanephros development are of particular interest. Expression of the
antigen defined by
FH3 followed by the
antigen defined by FH4 appeared only after six weeks of gestation in the convoluted tubuli at the central region of metanephros, and propagated rapidly into those at the peripheral cortex region with a simultaneous regression at the central region. The regression of FH4
antigen was more rapid than that of
FH3. All three
antigens were expressed in the medullar thin tubuli, which develop into the thin-limb of Henle's loop, in which only the
antigens defined by
FH3 and FH4 persisted and FH6
antigen disappeared. Well-differentiated, but not undifferentiated,
renal adenocarcinomas strongly expressed the
antigens defined by FH4 and FH6, although the
antigen defined by FH6 was expressed in more differentiated
tumor cells than the
antigen defined by FH4. Well-differentiated cells organized into tubular structures showed a strong expression of these
differentiation antigens. However, some
tumor cells that were organized into tubular structures, but were characterized by undifferentiated cytomorphology (larger nucleus and smaller volume of cytoplasm), did not express FH4 and FH6
antigens. Thus, cytodifferentiation and histotypic differentiation proceed independently within kidney
tumors. The fucosylated type 2 chain structures defined by these three
monoclonal antibodies are useful markers that indicate the degree of
tumor differentiation.