Immunological responses of the rabbit host to infestation by the brown ear-tick Rhipicephalus appendiculatus (Acarina:Ixodidae).

Rabbits developed resistance to Rhipicephalus appendiculatus instars following repetitive infestations. Rejection was accompanied by elevated IgM and IgG titres. Extracts of salivary gland, mouth-part cement and whole ticks induced a dose-related lymphocyte transformation. Skin-provocation tests with tick extracts elicited an immediate type-I hypersensitivity reaction with a delayed time-course which was influenced by antihistamines. Passive-transfer studies indicated that resistance was partially transferred with serum. A comparative histological study of the attachment sites of larvae on resistant and naive hosts demonstrated the role of eosinophils and macrophages during the initial phase of infestation. Possible rejection mechanisms are discussed in the light of these and other findings.