A NOVEL METHODOLOGY FOR QUANTITATING THE ENHANCEMENT OF CUTANEOUS DELAYED-TYPE HYPERSENSITIVITY BY IMREG-1 - A MEASURE OF THE IMMUNOPOTENTIATION OF CELL-MEDIATED-IMMUNITY

IMREG-1, a low-molecular-weight immunomodulator derived from normal hu man leukocyte dialysates, has been shown to enhance cutaneous delayed- type hypersensitivity (DTH) responses to recall antigens. Both IMREG-1 and the biologically active peptides (Tyr-Gly[YG] and Tyr-Gly-Gly[YGG ]) identified therein are able to accelerate and enhance DTH in a conc entration-dependent manner. In this study, we describe a novel methodo logy for analyzing and quantitating this response and demonstrate its use with data comparing drug to placebo. Subjects demonstrating prior sensitivity to a recall antigen (tetanus toroid) received intradermal injections of tetanus toroid alone (control) and either dilutions of L MREG-1 plus antigen, or placebo plus antigen, on the volar surface of the forearm. The response, as measured by area of erythema, was calcul ated and plotted as a function of time. The area under the resulting c urve (AUG) was then determined by use of the trapezoidal rule, whereby the area of a trapezoid formed between each sequential pair of time p oints was calculated. The AUC computed for each site receiving a dilut ion of IMREG-1 or placebo (test) was compared with the AUC computed at the site that received antigen alone (control) by means of a test to control (T/C) ratio. The respective T/C ratios for designated dilution s of IMREG-1 or placebo provided a basis of comparison between respons es to IMREG-1 and to placebo, while also controlling for individual se nsitivity in response to antigen. We demonstrate in this study that th e enhanced response to IMREG-1 plus antigen is statistically different from that seen with placebo plus antigen. This response, as a functio n to time, predominantly appears in the 12- to 24-hr period after inje ction, illustrating the ability of the immunomodulator to accelerate, enhance, and sustain a DTH response. We further conclude that the effe ct of LMREG-1 in this context is one of immunopotentiation of cell-med iated immunity. (C) 1995 Academic Press, Inc.