Immunologic properties of conjugates of ragweed antigen E with various alkoxypolyethylene glycols

Antigen E from ragweed pollen has been modified by coupling about 8 of its 18 epsilon-amino groups with various alkoxypolyethylene glycols (ROPEG). These glycols include methoxy-PEGs of 2,000 and 5,000 daltons, n-laruyloxy-PEG of 1,200 daltons (BRIJ-35), and p-isooctylpohenoxy-PEG of 3,300 daltons (Triton X-705). The immunogenic and immunosuppressive activities of these conjugates were tested in mice. They showed reduced immunogenicity for antigen E-specific IgE and IgG antibody responses although the BRIJ-35 conjugate showed only slightly decreased immunogenicity. The protein portion of the conjugate molecules appeared to contain the same antigenic determinants as in native antigen E. The alkoxypolyethyleneglycoxy portion of the conjugate molecules was found to be weakly immunogenic, since mice which had been immunized with such conjugates showed a transient weak IgE antibody response. All conjugates retained the immunosuppressive property of antigen E since the subcutaneous treatment of antigen E-sensitized mice with high doses of antigen E or of conjugate led to suppression of their specific IgE and IgG antibody levels.