Inhibition of delayed-type hypersensitivity by heparin depleted of anticoagulant activity

The intravenous or intraperitoneal injection of heparin fractions depleted of anticoagulant activity (HFDA) into mice, either at the time of immunization or challenge, inhibited hapten-specific delayed-type hypersensitivity (DTH) reactions. The loss was not due to functional elimination of sensitized lymphocytes, since mice sensitized with the contactant and then treated with HFDA retained their ability to transfer reactivity into normal syngeneic recipients. In contrast, lymphocytes from sensitized mice were unable to produce DTH reactivity in recipient mice pretreated with HFDA. The intravenous injection of HFDA resulted in a rapid, but transient increase in the number of circulating leukocytes. The intravenous injection of HFDA also reduced the footpad swelling that resulted from a local injection of concanavalin A. It is postulated that HFDA exercise their inhibitory effects on the DTH response by interfering with the migration of cells into the challenge site.