Does tocilizumab contribute to elevation of rheumatoid factor and induction of paradoxical syaloadenitis in rheumatoid arthritis patients?

A 56-year-old woman, treated with tocilizumab (TCZ) for 8 months for severe rheumatoid arthritis (RA), was admitted to the hospital due to the swelling and tenderness of parotid glands. The patient was diagnosed with seropositive erosive RA in 1988, and treated with different disease modifying antirheumatic drugs (DMARDs) that were used together with a low dosage of glucocorticoides, followed by biologic therapy with infliximab and adalimumab which also proved to be inefficient. The patient had an excellent initial response on TCZ therapy. After 8 months, she was presented with an extreme enlargement of parotid glands. Bacterial, viral, and granulomatous diseases were excluded. A spectrum of autoantibodies including anti-Ro and anti-La showed normal values, expect for slightly elevated anti-cyclic citrullinated peptide (anti-CCP) and extreme elevation of the rheumatoid factor (RF) to 10,100 IU/ml. The biopsy of salivary glands was done and histological specimen showed limphoplasmocytic syaloadenitis. Tocilizumab therapy was stopped and the dosage of glucocorticoids and methotrexate (MTX) was raised. After 6 weeks, the patient was in better condition with slightly lower levels of RF (9,010 IU/ml). We hypothesise that in this patient, TCZ stimulated RF hyper production which can induce a paradoxical secondary syaloadenitis in RA.