ANALYSIS OF THE ANTIGENIC PROFILES OF IMMUNOGENIC MOUSE TUMOR CELLS FOLLOWING DNA-MEDIATED GENE TRANSFER

Abstract

Non-self class I histocompatibility antigens can be recognized as distinct target antigens by cytotoxic T-lymphocytes. This is a strong immune reaction and is called alloreactivity. The possibility of using allograft rejection to generate tumor-specific immunity was studied. An allogeneic class I histocompatibility gene, the H-2Kb gene was introduced into a k haplotype tumor, K36.16 by DNA-mediated gene transfer. Thirty-seven H-2Kb-transformed K36.16 clones were isolated and studied individually. These Kb/K36.16 clones expressed different amounts of the exogenous H-2Kb antigens as well as the endogenous H-2Dk antigens on their cell surface and were found to be immunogenic. The level of H-2Kb expression on the cell-surface could not be correlated with the H-2Dk expression nor the tumorigenicity of the clones. As a further step to characterize the Kb/K36.16 clones, 2D-PAGE analyses of the clones were carried out. It was found that the 2D-PAGE profiles of the H-2Kb antigen in the clones and normal B6 spleen cells were different. The multi-spot H-2Kb antigenic profile of the B6 H-2Kb antigen comprise higher amounts of the acidic species. The Kb/K36.16 clones, however, exhibited a more heterogenous H-2Kb antigenic profile. Studies with glycosylation inhibitor, tunicamycin (Tm), showed that the multi-spot pattern was a result of the presence of different glycosylated forms of the H-2Kb antigen. A basic and lower MW spot could be seen upon inhibition of glycosylation by Tm. The clones exhibited differential sensitivity to Tm and the time required for the spots to disappear ranged from 2-8 hours. Although this differential behaviour could not be correlated with the level of H-2Kb gene expression on the cell-surface, it demonstrates the possibility of carbohydrate groups playing a role in the immunogenic behaviour of the clones. The presence of a tumor-specific transplantation antigen-H-2Kb antigenic complex was also tested by using the cross-linking reagent, dithiobis(sulfosuccinimidyl propionate). However, under the conditions studied, the presence of a tumor-specific transplantation antigen that is in close association with the H-2Kb antigen could not be detected.