Presence of aluminium in central nervous system of sheep repetitively inoculated with aluminium-adjuvants

Abstract

Aluminium (Al)-containing adjuvants promote an effective immune response but in sheep, they also induce local granulomatous reactions and accumulate in regional lymph nodes1. 21 lambs, divided into 3 groups (n=7 each) were inoculated during 15 months with 19 doses of different substances: A) Vaccines containing Al hydroxide; B) Al hydroxide only; C) PBS. Lumbar spinal cord and frontal lobe of the brain were studied by fluorescence microscopy with lumogallion, Graphite Furnace Atomic Absorption Spectroscopy and immunohistochemistry against glial fibrillary acidic protein (GFAP). Groups A and B showed higher Al concentration in spinal cord than group C (p=0.001). Yellowish fluorescence emission (590 nm), typical of Al, was detected as small aggregates associated to myelin sheets. The highest individual measurements were obtained in group B. GFAP was overexpressed in group B compared to group C (p=0.047). In sheep, Al from adjuvants may translocate from subcutaneous tissue to the CNS, inducing astrocyte activation.