A guinea-pig immunoglobulin-G linked agarose column was used to detect the immunoglobulin-G binding proteins (IGBP) in the ixodid ticks, Rhipicephalus appendiculatus, Amblyomma variegatum and Ixodes hexagonus. IGBPs were found in salivary gland extract (SGE) of the unfed ticks of all 3 species. The sizes of the IGBPs, as determined by SDS–polyacrylamide gel electrophoresis, differed between species. In R. appendiculatus 2 IGBP bands were detected in haemolymph collected from unfed females and males, and an additional 78 kDa IGBP was detected in haemolymph samples of male and female ticks that had fed for 6 days. Although there was no difference in the IGBP profile of SGE derived from unfed male and female R. appendiculatus, 2 new IGBPs were detected in the SGE of the male ticks after they had fed for 6 days. The possible function of IGBP in ticks is discussed.
