MANNAN-BINDING PROTEIN IN SERA POSITIVE FOR RHEUMATOID-FACTOR

Low levels of mannan binding protein (MBP) may protect against rheumat oid arthritis and other inflammatory conditions associated with agalac tosyl IgG. MBP concentrations were measured in 99 sera found to be pos itive for rheumatoid factor, at least 41 of which were from patients w ith rheumatoid arthritis, and the values compared to the data from 352 controls. MBP was undetectable in similar proportions of patients' an d control sera (4.0 and 4.3%, respectively), and low values generally were similarly distributed in the two groups. Overall, however, the pa tient values were distorted upwards relative to controls, consistent w ith an acute-phase response. These findings do not refute the proposed role for MBP-agalactosyl IgG-mediated complement activation in the pa thogenesis of rheumatoid arthritis, but certainly provide no support f or that hypothesis.