Influence of soluble proteins from the salivary glands of ixodid ticks on the in-vitro proliferative responses of lymphocytes from BALB/c and C3H/HeNmice

In the U.S.A., Borrelia burgdorferi, the causative agent of Lyme borreliosi s, is transmitted to humans by the ticks Ixodes scapularis and I. pacificus . Tick modulation of host immunity is an important factor in tick transmiss ion of such pathogens. The proliferative responses of lymphocytes from BALB /c and C3H/HeN mice exposed to the salivary-gland soluble proteins (SGSP) o f I. scapularis, I. pacificus or Dermacentor andersoni were therefore compa red in vitro. This produced the present report, the first to describe the e ffects of I. pacificus SGSP on the proliferative responses of a host's lymp hocytes in vitro. The effects of four concentrations of SGSP from each tick species were evaluated with unstimulated, and concanavalin-A-stimulated ly mphocytes of each mouse strain. The responses of lymphocytes from both mous e strains were significantly effected when exposed to SGSP derived from eac h tick species. Responses of the unstimulated lymphocytes to SGSP indicated that the proteins from I. pacificus suppressed in-vitro lymphocyte prolife ration to a greater degree than those from the other species investigated. For the concanavalin-A stimulated cells, however, suppression of the prolif erative responses was greatest for cells exposed to I. scapularis SGSP.