Predominance of IgG1 subclass of anti-Ro/SSA, but not anti-La/SSB antibodies in primary Sjögren's syndrome.

We have developed isotype-specific enzyme-linked immunosorbent assays to assess anti-Ro/SSA and anti-La/SSB IgG subclasses in 31 patients with primary Sjögren's syndrome. The anti-Ro/SSA antibody production was largely but not totally restricted to IgG1, whilst the anti-La/SSB subclass distribution varied from one patient to another. IgG2 and IgG3 anti-La/SSB was more frequent in those patients with extraglandular manifestations. In addition, there were more increases in the IgG2 and IgG4 contribution to anti-La/SSB activity in the 16 DR3-positive patients than in the remaining 10.