Endogenous Expression of CD80 Co-stimulatory Molecule Facilitates In Vivo Tumor Regression of Oral Squamous Carcinoma

Abstract

Background: Most tumor tissues, especially those of non-hematopoietic origin, do not express CD80 co-stimulatory molecules, possibly as a mechanism to evade immune surveillance. The objective of this study was to determine whether abundant endogenous CD80 expression on oral squamous cell carcinoma (SCC) early during tumor progression can facilitate immune elimination and reverse immune tolerance. Materials and Methods: The growth of regressor and progressor oral SCC lines with differing endogenous CD80 expression were examined in immunecompetent and -deficient mice. Immune effectors were determined by T-cell depletion experiments and immunohistochemistry. Results: Our studies show regression of early tumor growth when immunocompetent animals are inoculated with oral SCC progressor cell lines expressing abundant endogenous CD80. The CD80-induced antitumor response was due largely to induced T-cell responses. Conclusion: Our findings suggest that inadequate CD80 expression during early oral SCC formation may contribute to the escape of tumors from immune elimination. This information can be useful in the design of new approaches to generate more effective immunotherapy against this disease.