triple response


The triphasic response to the firm stroking of the skin characterized by sharply demarcated erythema, a brief blanching of the skin, and release of histamine from the mast cells, followed by arteriolar dilation causing an intense red flare that extends beyond the margins of the line of pressure, and ending with the appearance of a line wheal having the configuration of the original stroking.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.