Adjuvant oils induce arthritis in the DA rat. I. Characterization of the disease and evidence for an immunological involvement

An intradermal injection of Freund's incomplete adjuvant oil (FIA) without further additives was shown to induce erosive polyarthritis in dark Agouti (DA) rats, but not in Lewis rats. Histological examination revealed joint inflammation, first with polymorphonuclear cells and synovial hyperplasia, and subsequently, with multinucleated giant cells. Both constituents of FIA, mineral oil and Arlacel(®) A, as well as Pristane oil were arthritogenic, whereas vegetable oils were not. Re-administration of adjuvant oil after recovery failed to induce arthritis, thus making possible a role of specific immunity in this new form of arthritis in rats.