Characterizing the protective component of the alphabeta T cell response to transplantable squamous cell carcinoma.

There is increasing promise that cellular immune response may be manipulated to combat cancer; however, it is also clear that the immune response to cutaneous malignancy comprises different T cell activities that variably inhibit or promote tumor development. Thus, a better understanding of each of these activities is crucial to more effective clinical manipulation. To better characterize the protective anti-tumor effects of alphabeta T cells, we examined the growth of the transplantable squamous cell carcinoma (SCC) line, PDV, which is markedly inhibited in immunocompetent versusalphabeta T cell-deficient mice. We show that the protective response is composed of CD8(+) and interferon-gamma (IFNgamma)-producing CD4(+) cells, and that the most overt effects of these components on tumor growth in situ are to provoke overt focal necroses and to decrease the stromal bed. Tumors growing in the presence of any of these components also show reduced expression of Rae-1, a ligand for the activating NK receptor, NKG2D. Collectively, these data illustrate which components of the alphabeta T cell response against SCC have protective potential, and indicate which aspects of tumor physiology may be most susceptible to their activities.