LEWIS-Y ANTIGEN EXPRESSION IN HEPATOCELLULAR-CARCINOMA - AN IMMUNOHISTOCHEMICAL STUDY

Background. The altered expression of the Lewis blood group-related an tigens during malignant transformation can be used clinically as a tum or marker or as a prognostic indicator. The Lewis Y (Le(Y)) antigen, w hich is one of the Type 2 human blood group-related antigens, also is thought to behave as an oncodevelopmental cancer-associated antigen. I n this study, the authors examined the association between human Le(Y) antigen expression and the clinicopathologic features of HCC, includi ng its proliferative activity. Methods. Forty-six histologically confi rmed cases of HCC were studied retrospectively. Liver biopsy specimens from the main tumor of each case were obtained under ultrasonic guida nce before treatment was initiated. The formalin fixed, paraffin embed ded serial sections were immunostained using a modification of the avi din-biotin-peroxidase complex method, with a primary monoclonal antibo dy (MoAb) directed against the Le(Y) antigen (BM-1/JIMRO). The relatio nship between Le(Y) antigen expression and the HCC's proliferative act ivity was analyzed similarly by immunohistochemical methods using a pr imary MoAb directed against the Ki-67 antigen (MIB 1). In addition, to clarify the relationship between Le(Y) antigen expression and the his tologic heterogeneity within HCC, seven cases of surgically resected H CC also were immunostained. Results. The Le(Y) antigen was detected on the membrane and in the cytoplasm of the cancer cells. Of the 46 HCC cases, 20 (43.5%) expressed the Le(Y) antigen in the tumor cells. Ther e was no correlation between Le(Y) antigen expression and the maximum tumor dimension or the Stage. However, the incidence of Le(Y) antigen- positive cases in poorly differentiated HCCs was found to be significa ntly higher than that in well or moderately differentiated HCCs (P < 0 .01). In resected HCC cases, Le(Y) antigen expression within HCC nodul es was frequently greater in the less differentiated tumor than in adj acent differentiated tumor. Moreover, the incidence of Le(Y) antigen e xpression in alpha-fetoprotein (AFP)-positive (AFP greater than or equ al to 200 ng/ml) HCC cases was significantly higher than that in AFP-n egative (AFP < 200 ng/ml) HCC cases (P < 0.05). Furthermore, the mean value of the Ki-67 labeling index in Le(Y) antigen-positive HCC cases (25.2 +/- 11.3%) was significantly higher than that in Le(Y) antigen-n egative HCC cases (9.4 +/- 4.1%) (P < 0.001). Conclusions. These resul ts suggest that Le(Y) antigen expression correlated closely to the ded ifferentiation and proliferative activity of HCC.