The invention relates to compounds exhibiting immuno-regulatory activity as determined by measuring the compounds ability to modulate production of NO by a cell. Preferred compounds include or consist of a sequenceAAL AAQ AAG AAVwherein AAL is a substituted or unsubstituted non-polar amino acid selected from the group consisting of Ala and Leu wherein AAQ is a substituted or unsubstituted amino acid selected from the group consisting of Gln, Pro, and Ala wherein AAG is a substituted or unsubstituted amino acid Gly, and wherein AAV is a substituted or unsubstituted non-polar amino acid selected from the group consisting of Val and Ala. In one embodiment, the compound consists of a tripeptide selected from the group AQG, MTR, VVC, and mixtures thereof.
