Background. The role of vaccination in the development of autoimmunity has been extensively discussed in the literature; nevertheless, it remains vague. Whether there is a causal relationship between vaccination and the mechanisms leading to the autoimmune phenomena has yet to be discovered. Therefore, characterization of autoimmune disease in Wistar rats immunized with influenza vaccine was the basis of the current report.

Materials and methods. Forty-three Wistar male rats (30 with AA and 13 healthy) were used. Two groups of animals with adjuvant arthritis (AA) and one group of healthy rats were immunized intramuscularly (i.m.) four times with 0.01 ml of influenza vaccine. Prophylactic and therapeutic vaccinations were made. Untreated groups (with AA and healthy) served as controls. Body and organ weight, blood and pro/antioxidant system indices in serum, joint swelling, development of polyarthritis, as well as histological changes in joints, liver and lungs were evaluated.

Results. A more aggressive pathological process with elevated ESR and MDA levels and histological changes in the lungs and liver were observed in vaccinated animals. Despite a significant joint swelling and changes in periarticular soft tissues (increase of inflammatory infiltration, edema and angiomatosis), changes in the synovium and cartilage of vaccinated animals did not differ from those in AA controls, although the therapeutic vaccination induced more pronounced edema and inflammatory infiltration with granulocytes and macrophages in synovium, fissures (in 30% of animals), enhanced the rise of erosium (by 13.9%), usures (by 31.6%) and the thinning of cartilage (by 25%). We failed to detect any evidence of a clinically observed autoimmune process in healthy rats after vaccination, except only minimal histological changes in joints of some animals.

Conclusions. Our preliminary findings are the first to show the presence of a certain relationship between vaccination and the exacerbation of autoimmune disease. The use of commercial influenza vaccine enhances the autoimmune process expressed by increased joint swelling and changes in soft periarticular tissues of experimental animals, and induces changes in the lungs. A greater impairment was observed after therapeutic vaccination.

Keywords: rats, adjuvant arthritis, vaccination