The data from in vitro and animal experiment study has showed that costimulaory molecule B7 1 plays an important role in antitumor immunity In the present study

B7 1 expression was observed in 130 samples from a veriety of human malignancies by using immunocytochemistry

in situ hybridization and RT PCR combined with dot hybridization and B7 1 specific Mab and probe The results demonstrated B7 1 expression on tumor cells in 76 cases at both protein and mRNA level Forty two specimens were stained with B7 1 HLA ABC and HLA DR Mab and 26 showed that the three antibodies used all were positive Together with the achievement in tumor antigen study

the present findings imply that in most tumors （if not all） the tumor cells have all the requisite element to elicit anti tumor rejection response

the heterogeneous mechanism for tumor escape from immunosurvillance should be emphasized