Characterization of contrasensitizing antibodies

Abstract This paper describes experiments on the nature of humoral antibodies which suppress induction of delayed hypersensitivity in mice to purified proteins, i.e., contrasensitizing antibodies. These antibodies may be analogous to those responsible for afferent or early central immunosuppression in immunological enhancement phenomena and for similar forms of immunosuppression sometimes referred to as immune deviation, split tolerance, or preimmunization tolerance. CF-1 mice were sensitized with either human serum albumin or ovalbumin in incomplete Freund adjuvant, were injected with contrasensitizer-rich mouse antisera or fractions thereof, and subsequently were skin-tested to measure the relative capacities of antisera or their components to interfere with sensitization. Agar gel zone electrophoresis located Contrasensitizing activity among the γ 1 globulins, and this identification was confirmed by DEAE cellulose chromatography. Fractionation on Sephadex G-200 dextran columns showed the inhibitory activity to be among molecules of approximately 170,000 molecular weight, and a combination of chromatographic procedures further indicated that this activity is due to specific antibodies closely associated with mouse IgF or 7S γ 1 globulin. Contrasensitizing antibodies also were found to be heat-stable, and although precipitin and passive hemagglutination antiserum titers often correlated well with immunosuppressive activity, neither was equivalent to it.