Basophils in skin reactions of mast cell-deficient mice infested with Dermacentor variabilis

Acquired resistance to ticks in guinea pigs has been found to be associated with basophil-rich skin reactions. Mice, which are generally believed to possess few, if any basophils, also acquire resistance following repeated tick infestations and this has been found to be associated with increased numbers of dermal mast cells. Mast cell-deficient W/Wv mice have, however, also been shown capable of acquiring resistance after two infestations with Dermacentor variabilis larvae. In the studies described here, we have examined, with the electron microscope, skin reactions in W/Wv and +/+ mice undergoing their third infestation with Dermacentor variabilis. Basophils, along with neutrophils and eosinophils, were identified using established criteria. The possibility that basophils contribute to various pathogenetic mechanisms in these and other strains of mice is discussed.