The use of new recombinant antigens may increase the sensitivity and specificity of the detection of anti Ro and anti La antibodies in Sjögren's syndrome.
To determine the immune reactivity of sera from patients with Sjögren's syndrome, against fusion recombinant proteins (prf) Ro60 Kd, Ro52 Kd and La48 Kd expressed in E coli and recombinant protein Ro52 Kd, expressed in baculovirus (prb).
Serum samples from 46 patients with a diagnosis of Sjögren's syndrome, according to the European criteria of 1997, were studied. Using conventional ELISA assays, 32 patients had positive anti Ro antibodies (group A) and 16 patients had negative anti Ro and anti La antibodies, but had positive antinuclear antibodies or rheumatoid factors (group B). Antibodies against recombinant proteins were measured by ELISA or Western Blot.
Reactivity against prf Ro60 was present in 69% of samples from group A patients and in 36% of samples from group B. Reactivity against prf Ro52 was present in 94% of samples from group A and 50% of samples from group B. Reactivity against prb Ro52 was present in 75% of samples from group A and 40% of samples from group B. Reactivity against prf La was present in 78% of samples by ELISA and 97% of samples by Western Blot. In 10 of 14 serum samples from group B patients, there was reactivity against at least one recombinant protein.
A high prevalence of reactivity against recombinant Ro and La proteins was detected in serum samples from patients with Sjögren syndrome.