Histamine releasing and anti-inflammatory activities of MCD-peptide and its modified forms.

MCD-peptide and its modified analogues have been tested for their histamine-releasing activity on mast cells and for the ability to inhibit vascular permeability in rat's skin. Reduction of disulphide bonds, modification of the basic lysine ɛ-NH2 groups and histidines in MCD-peptide suppressed its histamine-releasing action. Modification of the basic arginine guanidino groups did not alter this activity. MCD-peptide inhibited the vascular permeability induced by histamine and serotonin. Modification of MCD-peptide lysines and arginines abolished the inhibiting activity.