Preferential induction of cell-mediated immunity by chemically modified carcinoembryonic antigen

Modification of carcinoembryonic antigen (CEA) with various chemicals was investigated. Modification of CEA with dimethylsulfate or acetic anhydride resulted in derivatives which preferentially induced delayed-type hypersensitivity (DTH) against native CEA in mice. The strength of the DTH reaction was dependent on the number and chemical nature of modifying groups as well as on the immunizing dose. The strongest DTH reaction without detectable formation of antibodies was achieved by low dose immunization using heavily methylated CEA.