Qualitative difference of subcellular localization of tumor-associated carbohydrate (Le(x)) antigens in renal cell carcinoma and normal kidney

Glycan gimmickry by parasitic helminths: a strategy for modulating the host immune response?

Parasitic helminths (worms) co-evolved with vertebrate immune systems to enable long-term survival of worms in infected hosts. Among their survival strategies, worms use their glycans within glycoproteins and glycolipids, which are abundant on helminth surfaces and in their excretory/ secretory products, to regulate and suppress host immune responses. Many helminths express unusual and antigenic (nonhost-like) glycans, including those containing polyfucose, tyvelose, terminal GalNAc, phosphorylcholine, methyl groups, and sugars in unusual linkages. In addition, some glycan antigens are expressed that share structural features with those in their intermediate and vertebrate hosts (host-like glycans), including Le(X) (Galbeta1-4[Fucalpha1-3]GlcNAc-), LDNF (GalNAcbeta1-4[Fucalpha1-3]GlcNAc-), LDN (GalNAcbeta1-4GlcNAc-), and Tn (GalNAcalpha1-O-Thr/Ser) antigens. The expression of host-like glycan determinants is remarkable and suggests that helminths may gain advantages by synthesizing such glycans. The expression of host-like glycans by parasites previously led to the concept of "molecular mimicry," in which molecules are either derived from the pathogen or acquired from the host to evade recognition by the host immune system. However, recent discoveries into the potential of host glycan-binding proteins (GBPs), such as C-type lectin receptors and galectins, to functionally interact with various host-like helminth glycans provide new insights. Host GBPs through their interactions with worm-derived glycans participate in shaping innate and adaptive immune responses upon infection. We thus propose an alternative concept termed "glycan gimmickry," which is defined as an active strategy of parasites to use their glycans to target GBPs within the host to promote their survival.

Monoclonal antibodies against renal tumors: the potential application in discrimination of ambiguous adenocarcinoma or transitional cell carcinoma of kidney

PURPOSE

We tested the discrimination ability of 2 monoclonal antibodies, mAB 90 and 2-2, in renal carcinomas, including renal cell carcinoma and transitional cell carcinoma of the kidney.

MATERIALS AND METHODS

Two monoclonal antibodies raised in renal adenocarcinoma (mAB 90, IgG3 subclass and mAB 2-2, IgG1 subclass), have been generated in our laboratory by hybridoma technique. The tumor associated antigens recognized by these IgG subclass monoclonal antibodies are located in the cell membrane of tumor cells. Antibodies were purified from mice ascites through protein A-Sepharose 4B affinity column and then conjugated with fluorescein isothiocyanate fluorescence by dimethyl sulfoxide method. The binding activity of these antibodies was measured by direct immunofluorescence method and analyzed in a flow cytometer. Forty-five cases of renal cell carcinoma and 16 cases of transitional cell carcinoma of the renal pelvis were collected, and the recognition power of these 2 antibodies was tested. Frozen tumor tissues were prepared and allocated into single cell suspensions in phosphate buffered saline before adding diluted (1:10) conjugated antibodies. Irrelevant antibody and negative tumor cell lines without any reaction with these antibodies were used as background fluorescence control.

RESULTS

Reactivities of mAB 90 and mAB 2-2 for renal cell carcinoma tissues were 80 and 91%, respectively. On the contrary the reactivities of mAB 90 and mAB 2-2 for transitional cell carcinoma of renal pelvis tissues were 0 and 69%, respectively. mAB 90 (+)/mAB 2-2 (-) expression pattern had 76% accurate diagnostic rate for renal cell carcinoma and mAB 90 (+)/mAB 2-2 (+) pattern had 69% accurate diagnostic rate for transitional cell carcinoma of the kidney.

CONCLUSIONS

When facing pathologically ambiguous kidney tumors, the binding specificity of mAB 90 and mAB 2-2 may be useful for discrimination between renal cell carcinoma tumors and transitional cell carcinoma of the renal pelvis.

Cell adhesion molecule expression by vascular endothelial cells as an immune/inflammatory reaction in human colon carcinoma

The cell adhesion of inflammatory cells to vascular endothelial cells is an important process in the recruitment of inflammatory cells to the site. In cancer tissue, infiltration of inflammatory cells has been suggested to be a mechanism of host resistance. To clarify this infiltration mechanism, we investigated cell adhesion molecule expression (E-selectin, P-selectin, and ICAM-1) in vascular endothelial cells by immunohistochemistry in colon carcinoma. Venules distributed along the invasive margin expressed E- and P-selectins and ICAM-1. These phenotypical features are identical to those of endothelial cells observed in active inflammatory lesions, and the vessels can, therefore, be designated as immunologically activated vessels. Nevertheless, the majority of blood vessels within the tumor lacked immunoreactivity for all these adhesion molecules and, therefore, could be designated as immunologically inactive vessels. Granulocytes, lymphocytes and macrophages, bearing the counter-receptors of these adhesion molecules, were more densely distributed along the invasive margin. In contrast, few inflammatory cells were present within the tumor. In conclusion, the present study has demonstrated the phenotypical heterogeneity of tumor vessels; those for inflammatory cell infiltration to the tumor and those for the nutrient supply to the tumor.

Histochemical and cytochemical localization of blood group antigens

The oligosaccharide structures of blood group antigens are not the primary gene products; they are constructed in a stepwise manner by adding particular sugar to precursor oligosaccharides via several glycosyltransferases coded for by different blood group genes (Watkins 1966, 1978, 1980). Consequently, final profiles of antigens expressed in each cell type are influenced by many different factors such as the intrinsic composition of glycosyltransferase species which are defined by the genotype of the individuals, relative activity or amount of these enzymes (repression, derepression or induction of the enzymes), competition between enzymes with overlapping substrate specificity, the organization of the enzymes in membranes, utilizability of precursors and specific substrate sugars, and the activity level of degradating enzymes. Changes in the antigen profiles during maturation, differentiation and malignant transformation are thought to be intimately related to the variability of these factors. Although great importance attaches to histo- and cytochemical information on the distribution and levels of glycosyltransferases and messenger RNA corresponding to the relevant enzyme, detailed and precise localization of the blood group antigens and their variants is the base line for analyzing these complex factors. On the basis of individual genotype and histochemical findings about the antigen distribution and the interrelationship between cells and cellular components producing different antigenic structures (cellular and subcellular mosaicism), we can deduce precursor oligosaccharide levels as well as the status of gene activation and its primary product, glycosyltransferases. Thus, these findings are a prerequisite for further analysis at the molecular genetic level. As emphasized in this article, lectin staining or immunostaining methods with MAbs combined with glycosidase digestion procedures are powerful tools for in situ analysis of carbohydrate structures in histochemical systems. Although in some cases valuable results have been obtained by applying the technique, our knowledge concerning the distribution of complex carbohydrate structures is still far from satisfactory. Along with well defined MAbs and lectins, the key to developing our methods further is successful introduction of glycosidases, in particular, endoglycosidases since these reagents are indispensable for analyzing the inner core structures and glycoconjugate species of the blood group antigens. Application of these techniques at the ultrastructural level is an alluring possibility, even though many difficulties must be overcome. Although their functional roles have not yet been determined, a diverse array of macromolecules is known to be decorated with blood group-related antigens.(ABSTRACT TRUNCATED AT 400 WORDS)