The present invention relates to a method of specifically suppressing an undesired immune response in a mammal suffering from such a response. The method comprises: i) preparing a construct comprising at least one discrete antigenically recognizable moiety corresponding to an antigenic determinant of an antigen causing the undesired immune response bound to a pharmacologically acceptable carrier wherein the number of the moieties bound to the carrier and the spacing of the moieties on the carrier are such that the construct does not elicit an immune response to the moieties but does directly compete with the antigen for receptors on an immunocompetent cell that recognizes the determinant, and thereby the construct specifically suppresses the undesired immune response; and ii) administering the construct to the mammal in an amount such that suppression of the undesired immune response is effected. The invention further relates to constructs suitable for use in the above method and to methods of making same.