Early stage gastric MALT lymphoma with high-grade component cured by Helicobacter pylori eradication

A 68-year-old woman was diagnosed with gastric lymphoma of the mucosa-associated lymphoid tissue (MALT) type with a high-grade component. Surgical treatment was recommended because of the presence of the high-grade component, but she refused surgery. As an alternative, she received Helicobacter pylori eradication treatment, which successfully induced regression of the lymphoma. She shows no sign of recurrence endoscopically and histologically, as of 29 months after the eradication treatment. Moreover, the B-cell monoclonality and Helicobacter pylori infection demonstrated at diagnosis has disappeared. This is one of the rare cases of gastric lymphoma of the MALT type with a high-grade component cured by Helicobacter pylori eradication alone.

Different expression of Tn and sialyl-Tn antigens between normal and diseased human gastric epithelial cells

Thomsen-Friedenreich antigen (T antigen) has been supposed to be a cancer-specific carbohydrate antigen. We have previously shown that one third of the Japanese population normally expressed T antigen in gastric surface epithelia and the other two thirds expressed fucosyl-T antigen. Their sialylation and blocked-synthesis were associated with diseased conditions. In the present study, we studied gastric surface epithelial expression of monosaccharide antigen Tn, i.e., a precursor of T antigen, and sialyl-Tn. Normal fundic and pyloric epithelia, respectively, expressed Tn supranucleally and cytoplasmically, but did not express sialyl-Tn. In the intestinal metaplasias and intestinal-type adenomas, goblet cells expressed sialyl-Tn in their vacuoles, and absorptive cells expressed Tn apically. In gastric-type adenomas, Tn, but not sialyl-Tn, was detected. Intestinal-type cancers expressed Tn and sialyl-Tn more often than the diffuse-type cancers. Five cancers did not express Tn, sialyl-Tn, or the T-related antigens. In these, four were diffuse-type cancers. We concluded that: a) normal gastric epithelial cells express Tn; b) metaplastic differentiation is associated with sialylation of Tn and c) expression of Tn and sialyl-Tn is depressed in the gastric cancers.

Novel monoclonal antibody, SO-MU1, against human gastric MUC5AC apomucin

Human gastric mucins were chemically deglycosylated with trifluoromethanesulfonic acid. A mouse monoclonal antibody (MoAb), SO-MU1, was established against the deglycosylated mucins. SO-MU1 recognized not only the deglycosylated mucins but also the native gastric mucins. Periodate treatment of the native mucins increased the SO-MU1 reactivity. Trypsin digestion abolished the antigenicity. Human gastric cDNA expression library was screened with SO-MU1 and a mucin cDNA clone was obtained. Its sequence contained the MUC5AC tandem repeat domain. We studied gastrointestinal distribution of the SO-MU1-reactive antigen immunohistochemically. Gastric surface epithelial cells and parietal cells expressed the antigen, but the glandular cells did not. The antigen was also detected in the small intestine and biliary tract but not in the colon and pancreas. In summary, (1) MoAb SO-MU1 was raised against human gastric mucins, (2) it recognized human gastric MUC5AC apomucin, and (3) the SO-MU1-reactive antigen showed characteristic distribution in the organs of endodermal origin. MoAb SO-MU1 is the first MoAb against MUC5AC.

Changes in the expression of sialyl-Lewisx, a hepatic necroinflammation-associated carbohydrate neoantigen, in human hepatocellular carcinomas

BACKGROUND

Malignant transformation of cells is associated with the change in their carbohydrate antigens. Sialyl-Lewisx (SLEX) is a necroinflammation-associated carbohydrate antigen (NICA) of liver cells, because it is newly expressed in chronic inflammatory liver diseases. The authors addressed whether this type of carbohydrate antigen shows cancer-associated changes.

METHODS

Expression of SLEX and its related structures was studied immunohistochemically using the well characterized monoclonal antibodies in 13 small and 6 advanced hepatocellular carcinomas (HCC).

RESULTS

SLEX was negative in 7 small HCC, which were well differentiated histologically. Both negative and positive cells were observed in 6 other small HCC. When positive, SLEX was expressed membranously or cytoplasmically. The membrane positive HCC cells were well differentiated. Cytoplasmic expression was observed in the less differentiated cells. The SLEX-negative cells were associated with any degree of differentiation. In six advanced HCC, the expression of SLEX could also be correlated with their histologic differentiation. HCC expressed sialyl-type 2 chain N-acetyllactosamine (2-NAcLc), but not 2-NAcLc, Lewisx, and Lewisy.

CONCLUSIONS

SLEX, a NICA, showed HCC-associated changes that were dependent on the levels of HCC cell differentiation. Suppression and reactivation of alpha 1-3fucosyl-transferase was a possible enzymatic basis for the observed changes.

Fucosylated Thomsen-Friedenreich antigen in alpha-anomeric configuration in human gastric surface epithelia: an allogeneic carbohydrate antigen possibly controlled by the Se gene

Human gastric surface epithelial cells display the ABH blood group antigens with the core structure of N-acetyllactosamine (NAcLc). Their expression is under the control of the secretor gene Se. The Thomsen-Friedenreich (T)-antigen (Gal beta 1-3GalNAc) is another core structure of the ABH antigens. We examined the gastric surface epithelial expression of T- and alpha 1-2 fucosylated T (FucT) histochemically with peanut agglutinin (PNA) and monoclonal antibody (MAb) MBr1, respectively. Eight of 24 individuals exhibited the PNA-reactive antigen (i.e., T-expressers) and others the MBr1-reactive antigen (i.e., FucT-expressers). alpha-L-fucosidase digestion of the FucT-positive tissues and beta-galactosidase digestion of the T-positive tissues, respectively, made them reactive with PNA and the antibody specific for GalNAc alpha-O-Ser/Thr. There was a remarkable correlation among reactivities with MBr1, Ulex europaeus lectin 1 (UEA1), and anti-Leb MAb CO-431. ABH blood group status had no correlation with this expression. We conclude that human gastric surface epithelial cells constitutionally synthesize T in alpha configuration (i.e., Gal beta 1-3GalNAc alpha-O-Ser/Thr) and that it was alpha 1-2 fucosylated only in the FucT-expressers. alpha 1-2 fucosylation of T is suggested to be regulated by the Se gene.