Effects of tolerogenic conjugates in a canine model for reaginic hypersensitivity. I. suppression of hapten-specific IgE antibody response

Determinants of ryegrass pollen cytochrome c recognized by human IgE and murine monoclonal antibodies

In attempts to produce fragments of an allergenic molecule which would retain allergenic and/or antigenic determinant(s), the cytochrome c of ryegrass (RG) pollen, which had been shown to be an allergenic constituent of this pollen, was digested with trypsin and chymotrypsin and the resulting fragments were separated by high performance liquid chromatography. Several of these fragments were shown, with the aid of the radioallergosorbent test and solid phase radioimmunoassays, to bind IgE antibodies present in a pool of six sera from grass-sensitive patients and three murine monoclonal antibodies, designated as Mab 41, Mab 42 and Mab 43, which had been originally produced against the crossreacting cytochrome c of Kentucky bluegrass (KBG). In summary, (i) fragments C-67 and C-74 reacted with all antibodies, (ii) fragments T-45, T-46 and C-69 bound to human IgE antibodies as well as to Mab 41 and Mab 42, but not to Mab 43, (iii) fragment T-44 reacted only with Mab 41 and Mab 42, and (iv) fragment C-83 bound only Mab 42 and Mab 43. On the basis of these results, it is concluded that (i) immunochemically active fragments of the RG cytochrome c can be readily produced by enzymatic degradation, (ii) there is significant crossreaction between the antigenic determinants of RG and KBG cytochromes c, (iii) whereas all fragments possessed at least two of the original antigenic determinants, fragments C-83 and T-44 were devoid of allergenic determinants, (iv) the antigenic determinants recognized by Mab 41 and Mab 42 were different from those reacting with human IgE antibodies and Mab 43, (v) each of the three monoclonal antibodies recognized a distinct antigenic determinant, (vi) fragments C-67 and C-74 possessed all determinants recognized by the human IgE and mouse antibodies used.

A method for the preparation of protein-protein conjugates of predetermined composition

A novel procedure for the synthesis of well-defined protein-protein conjugates is described using ovalbumin (OA) and IgG as test proteins. This procedure involves the highly selective and rapid reaction of alkyl halide and sulfhydryl groups, which have been grafted, respectively, onto the proteins to be conjugated. Accordingly, iodoacetylated IgG, (ICH2CO)nIgG, was prepared by the reaction of the epsilon-amino groups of IgG with the N-hydroxysuccinimide ester of iodoacetic acid (NHIA), the degree of iodoacetylation (n) being proportional to the concentration of NHIA. OA was reacted with S-acetylmercaptosuccinic anhydride (SAMSA) under conditions yielding, on the average, a monosubstituted derivative. Following removal of the protective S-acetyl group, the resulting -SH derivative of OA was reacted with (ICH2CO)nIgG. The OAx-IgG conjugates so produced were characterized by gel filtration, specific radioactivity (using tritiated OA) and immunodiffusion. It was found that the average number of OA molecules coupled per IgG molecule could be controlled by varying the degree of iodoacetylation of IgG.