Identification of rat mast cell--derived chemoattractant factors for lymphocytes

Rat peritoneal and pleural mast cells have been demonstrated to release their granule-associated mediators, including chemotactic factors for eosinophilic polymorphonuclear leukocytes, after challenge with rabbit anti-rat F(ab')2 antisera in vitro. The presence of increased numbers of lymphocytes as well as eosinophils 6 to 24 hr after an initial immediate hypersensitivity reaction in the skin led to the present studies, which demonstrate the immunologic release of three chemoattractant factors for lymphocytes. One factor is chemotactic for nylon wool nonadherent rat splenic lymphocytes, a second factor is chemotactic for adherent rat splenic lymphocytes, and the third factor is chemokinetic for both nonadherent and adherent rat splenic lymphocytes. In addition, a high-molecular-weight inhibitor of lymphocyte migration was identified. Immunologic challenge of rat mast cells in vitro results in the release of lymphotactic activity, suggesting a possible explanation for the appearance of a lymphocytic infiltrate in the late phase of the immediate hypersensitivity reaction.