Differences in antigen expression between neoplastic and nonneoplastic gallbladder epithelium - An immunohistochemical study

Immunoreactivity for a panel of 15 monoclonal antibodies (MAbs), which are known to react with different gastrointestinal tumor antigens, was assessed in formalin-fixed paraffinembedded sections that were prepared from cholecystectomy specimens obtained from Mexican patients. Each case was classified histologically into one of the following groups: (1) invasive adenocarcinoma (N=21), (2) high-grade dysplasia (carcinoma in situ) (N=2), (3) low-grade dysplasia (N=4), hyperplasia (4) (N=15), and (5) chronic cholecystitis (N=10). Significant differences (P<0.05) were identified among the five histopathologic groups in the proportion of epithelial cells demonstrating immunoreactivity with MAbs to Lewis^b; Lewis^a; sialylated Lewis^a; sialylated Lewis^a and Lewis^a; Y antigen; H antigen; X antigen; X-like antigen; 200-kDa protein of CEA; 180-, 160-, 50-, 40-kDa proteins of CEA; 30- to 37-kDa protein; and an undefined antigen identified by MAb 99-57, with invasive carcinoma more frequently being positive as compared to nonneoplastic (hyperplasia, chronic cholecystitis) epithelium. Significant differences were also observed among the five histopathologic groups (P<-0.0005) in the proportion of epithelial cells demonstrating immunoreactivity with MAbs to Y antigen and the 20- to 50-kDa glycoprotein. However, with these two antibodies immunoreactivity was more frequently found in nonneoplastic epithelium rather than in invasive carcinomas. No significant differences in immunoreactivity were detected among the different histologic groups with MAb to blood group B antigen, types 1 and 2. This study demonstrates that cellular antigens are both developed and lost during the process of neoplastic transformation in the gallbladder. Future studies including a greater number of cases with varying degrees of gallbladder intraepithelial neoplasia are necessary in order to be able to draw meaningful conclusions regarding the antigenic expression of epithelium at different stages of tumorigenesis.