1. The present study was carried out to determine the target cells and
tissues for anti-tick immunoglobulins using an indirect immunohistoch
emical technique. 2. Sections in triplicate prepared from unfed ticks
Rhipicephalus appendiculatus, R. evertsi and Amblyomma variegatum were
used to assess the cross-reactivity of serum from guineapigs naturall
y infested with these tick species or immunized against them. 3. The s
ections showed slight (+) to strong (++++) labelling of several struct
ures in the tick body, e.g. salivary gland, gut lumen and malpighian t
ubules, depending on the serum used. 4. The immune serum resulting fro
m the immunization of guinea pigs with an extract of unfed nymphs of R
. appendiculatus ticks showed the most intense cross-reactivity with t
he sections examined.