ULTRASTRUCTURAL, CYTOCHEMICAL, AND IMMUNOCYTOCHEMICAL CHARACTERIZATION OF HEMOCYTES OF THE HARD TICK IXODES-RICINUS (ACARI CHELICERATA)

Haemocytes of the hard tick Ixodes ricinus were characterized on the b asis of their ultrastructure, their ability to ingest foreign material , and to produce or store molecules of the immune defence. Distinction was made between types of haemocytes according to the absence or pres ence of granular inclusions, shape and size of the lysosomal compartme nt or the rough endoplasmic reticulum, and ultrastructural and functio nal similarity to the corresponding haemocytes of insects. Three types of haemocytes were found in adult ticks: plasmatocytes and type-I and type-II granular haemocytes, respectively. The precipitated reaction product of acid phosphatase activity revealed the shape of the lysosom al compartment. The additional injection of particulate materials into the haemocoel further revealed the endocytic activity of the haemocyt es. The lysozyme-like immunoreactivity of the haemocytes suggests bact ericidal potential. Detection of immunoreactivity in haemocytes to a 2 5 kDa antigenic protein involved in cuticle formation further suggests their involvement in wound healing and encapsulation.