Hydrolysis of the tumor-associated antigen epitope gp100(280-288) by membrane-associated and soluble enzymes expressed by immature and mature dendritic cells

Abstract

The hydrolysis of the tumor-associated HLA-A2.1-restricted gp100(280-288) epitope by in vitro generated immature and mature dendritic cells (iDCs and mDCs) and by soluble supernatants prepared from these same cells, as well as the effect of the hydrolysis on in vitro immunorecognition, was studied by chromatographic and functional analyses. The results obtained indicate that exposure to iDCs induced a very rapid hydrolysis of the model peptide (half life, 62 s), resulting in complete loss of immunorecognition within 60 min. In the presence of mDCs, the hydrolysis kinetics were even faster (half life, 54 s), and the pattern of hydrolysis by-products was different from that observed for iDCs. Gp100(280-288) was also degraded in the presence of cell-free supernatants prepared both from iDCs and mDCS; in this case, degradation kinetics were slower, and the pattern of hydrolysis by-products was different from that observed in the presence of intact cells. The model epitope was degraded to non-immunogenic products by membrane and soluble enzymes expressed both by iDCs and by mDCs within periods of time that appear to be physiologically relevant. Development of antigenic formulations capable of protecting synthetic epitopes from these effects appears to represent a prerequisite for effective immunization procedures.