The human primary immune response to keyhole limpet haemocyanin: interrelationships of delayed hypersensitivity, antibody response and in vitro blast transformation.

The immune response to a protein antigen, keyhole limpet haemocyanin, was studied in fourteen normal subjects and twenty-one patients with solid tumours. Immunological responsiveness was assessed by intracutaneous skin testing, by haemagglutinin titres and by blast transformation. No significant difference was found in the kinetics or magnitude of the immune response among subjects immunized with 0·01, 0·10, or 5·0 mg. Delayed hypersensitivity to keyhole limpet haemocyanin developed in thirty-two of thirty-four skin tested; a positive antibody titre occurred in all; and thirty-one of thirty-five had positive responses. Patients in good general condition (Group 1) had significantly greater delayed hypersensitivity and antibody responses than the normals but similar responses. All immunological parameters were depressed in the patients with advanced neoplastic disease (Group 2). Although only skin test positive subjects had positive responses, no direct correlation was found between the degree of delayed hypersensitivity and the degree of blast transformation. Excellent correlation was demonstrated, however, between the response and the haemagglutinin titre (correlation coefficient +0·52, standard error ±0·09).