Clinical significance of MHC class II-associated invariant chain expression in human gastric carcinoma.

MHC class II antigens serve as restricted elements for cell presenting antigens to CD4+ helper T cells. CD4+ T cells and CD8+ cytotoxic T cells, which are tumor-infiltrating lymphocytes (TILs), and play a major role in the survey and attack against tumor cells in primary lesions. Invariant chain (Ii) has several functions in MHC class II-restricted antigen presentation. In addition, Ii is found to be closely involved in the regulation of anti-tumor immunity in several tumor types. However, the significance of Ii expression in tumor cells is not fully illustrated. Immunohistochemical staining of Ii expression was performed in 58 cases of human gastric carcinoma specimens. The prognostic analysis of patients with gastric carcinoma was also performed. A total of 67.2% (39/58) gastric carcinomas were found to be Ii-positive, whereas only 20.7% (12/58) showed positive immunoreactivity with anti-MHC class II determinants. Furthermore, Ii expression showed significant correlation with the differentiation of gastric carcinoma (p<0.05). Ii expression also showed an inverse correlation with the frequency of TILs around carcinoma tissues, as well as with the prognosis of gastric carcinoma (p<0.01). Ii expression is closely correlated with anti-tumor immunity in human gastric carcinoma. Therefore, Ii may serve as an independent clinical marker for poor biological behavior and prognostic analysis in patients with gastric carcinoma.