Quantitative studies of host immunoglobulin G in the hemolymph of ticks (Acari).

A radioimmunoassay was used to measure the concentration of host immunoglobulin G (IgG) in the hemolymph of female hard and soft ticks. Hyalomma excavatum Koch, Rhipicephalus sanguineus Latreille, Ornithodoros tholozani (Laboulbene and Megnin), and O. moubata (Murry) were fed on rabbits immunized with ovalbumin; Argas persicus (Oken) was fed on chickens immunized with cytochrome 'C.' At 24 h after feeding, the concentration of antiovalbumin IgG in the hemolymph was 7 micrograms/ml for H. excavatum, 5 micrograms/ml for R. sanguineus, and 0.15 micrograms/ml for O. moubata; the percentage of intact IgG molecules was 30, 44, and 100%, respectively. Host IgG was not detected in the hemolymph of O. tholozani and A. persicus. There was no increase in the concentrations of host IgG in the hemolymph of the soft ticks during the first week following the blood meal. The potential contribution to the resistance of hosts against ticks by host antibodies that cross into the tick hemocoel is discussed.