Tuftsin (an Ig-associated tetrapeptide) triggers the immunogenic function of macrophages: implications for activation of programmed cells.

Abstract

The immunoglobulin H-chain associated tetrapeptide tuftsin (Thr-Lys-Pro-Arg), known for its phagocytosis-stimulating activity, augmented the antigen-specific, macrophage-dependent education of mouse T [thymus-derived] lymphocytes. The investigation of stereospecific characteristics of the tetrapeptide, by use of structural analogs with different modifications, revealed strict structural requirements for eliciting the immunogenic activity of macrophages. The most important moiety for its activity was the dipeptide Pro-Arg. This finding is of interest in view of the appearance of this particular dipeptide in other bioregulatory peptides, including many of the peptide hormones. The significance of the appearance of a common structure in such molecules, which may act through specific receptors on different target cells, was discussed.