INVOLVEMENT OF INTERLEUKIN-3 IN DELAYED-TYPE HYPERSENSITIVITY

The in vivo functions of interleukin-3 (IL-3) were investigated by gen erating IL-3-deficient mice. Although hematopoiesis was unimpaired in homozygous mutant animals, contact hypersensitivity reactions were com promised. IL-3 was required for efficient priming of hapten-specific c ontact hypersensitivity responses, but was dispensable for T-cell-depe ndent sensitization to tumor cells. These findings reveal a critical r ole for IL-3 in some forms of delayed-type hypersensitivity. (C) 1998 by The American Society of Hematology.