Expression and purification of prostate-specific membrane antigen in the baculovirus expression system and recognition by prostate-specific membrane antigen-specific T cells

Antigen-specific immunotherapy of cancer depends on a consistent source of well-defined protein antigen. Production of recombinant protein offers the obvious solution to this problem but few comparisons of recombinant and nat ive proteins in cellular immune assays have been reported. We report expres sion of a putative immunotherapy antigen, prostate-specific membrane antige n (PSMA), in insect cell!, using a baculovirus vector. T cells stimulated w ith recombinant PSMA or native PSMA derived from the LNCaP cell line recogn ized both native PSMA and recombinant, baculoviral PSMA. These data indicat e that PSMA produced in Sf9 cells is immunologically cross-reactive with na tive PSMA and therefore suitable for immunotherapy as it is recognized by b oth cellular and humoral immune responses.