Low molecular weight IgM in primary Sjogren's syndrome

C. Salvarani, B. Casali, L. Boiardi, P. L. Macchioni, P. Rivasi, I. Portioli

Research output: Contribution to journalArticlepeer-review


Low molecular weight IgM (LMW IgM), the monomeric subunit of pentameric IgM, was measured in the serum of 27 patients with primary Sjogren's syndrome. LMW IgM was also measured in a control group consisting of 24 patients with psoriatic arthritis (PA) and 8 patients with active rheumatoid arthritis (RA). LMW IgM was found in the majority of patients with primary SS (63%) and those patients had a longer disease duration than those without SS (80.7±43.9 months vs 37±18.3, p = 001). Although the differences were not significant, SS patients with LMW IgM showed higher rates of: seropositive disease (71% vs 50%), anti-Ro (59% vs 30%) and anti-La antibodies (12% vs 0%), extraglandular involvement (76% vs 60%) and raised gammaglobulins levels (47% vs 30%) compared to those without LMW IgM. Our only two patients with active RA and vasculitis had LMW IgM. None of the patients with PA showed LMW IgM, regardless of their Kammer subgroup classification, disease activity or radiological evidence of erosions. The presence of LMW IgM in a high percentage of patients with primary SS appears to be the expression of a dysregulation of B cell state that may predispose these patients to developing malignant lympoproliferation.

Original languageEnglish
Pages (from-to)639-642
Number of pages4
JournalClinical and Experimental Rheumatology
Issue number6
Publication statusPublished - 1993

ASJC Scopus subject areas

  • Immunology
  • Rheumatology


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