Natural and synthetic peptides (other than neuropeptides) endowed with immunomodulating activities

A large number of peptides, in most cases of low or relatively low molecular weight, exert immunomodulating activities, i.e., they interact in vitro with various cell populations of the immune system and, in vivo, enhance or depress, according to the case, cell-mediated and humoral immune functions. Immunomodulating peptides include glycopeptides from the bacterial cell wall, natural acyloligopeptide ciclosporin, peptidic hormones from the thytide cyclosporine, peptidic hormones from the thymus, peptidic fragments of immunoglobulins and other plasma proteins, as well as peptides isolated from food proteins. An amazing diversity of structure exists among the various immunomodulating peptides. The molecular mechanisms of interaction between these peptides and the cells of the immune system remain, in most cases, to be elucidated. Possibilities of therapeutic applications exist for many of these immunomodulating peptides: one of them (ciclosporin) is widely used as an immunosuppressive drug, several others (glycopeptides, lipopeptides, tuftsin, thymic peptides) are under clinical investigation as immunostimulating and/or immunorestoring agents.