Isotypes of rheumatoid factors in rheumatoid arthritis and chronic liver diseases |
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Authors: | M Kaneko S Nishinarita N Kitamura Y Tomita Y Matsukawa S Sawada T Horie N Tanaka Y Arakawa |
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Institution: | (1) First Department of Internal Medicine, Nihon University School of Medicine, 30-1 Oyaguchi Kamimachi, Itabashi-ku, Tokyo 173-8610, Japan Tel. +81-3-3972-8111 (ext. 2402); Fax +81-3-3972-2893 e-mail: fwhs4775@mb.infoweb.ne.jp, JP;(2) Third Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan, JP |
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Abstract: | We studied isotype-specific rheumatoid factors (RFs) to clarify their significance in rheumatoid arthritis (RA) and to verify
the difference in RF isotypes between RA and chronic liver diseases (CLD). Isotype-specific RFs in RA and in CLD were measured
by enzyme-linked immunosorbent assay (ELISA). Most sera (n = 51, 94.1%) from RA patients contained some kind of RF isotypes (92.1% for IgM RF, 76.4% for IgG RF, and 43.1% for IgA RF),
and seronegative RA by ELISA was seen in only 11.8% (n = 6). The most characteristic combination of RF isotypes in active RA was IgG, IgA, and IgM. This combination of RF isotypes
changed to IgG plus IgM, according to the diminution of RA activity; then, we found only IgM RF in inactive RA. The titers
of each RF isotype also decreased in parallel with the activity of RA. IgA RF seemed to be the most sensitive factor for evaluating
the activity of RA. In CLD, almost the same high frequency (n = 49, 89.8% for IgM RF, 59.2% for IgG RF), with the same titer levels seen in RA, was observed. On the other hand, IgA RF
was significantly lower in frequency (n = 9, 18.4%) and in titer, compared with the finding in RA. Surprisingly, even in CLD, true seronegativity by ELISA was also
found in very few patients (n = 4, 8.1%). In CLD, positive RFs detected by agglutination assay were seen more often in chronic hepatitis than in liver
cirrhosis. In RA patients, significant associations of IgA RF and the serum concentration of IgA, and IgG RF and the serum
concentration of IgG, were observed. On the other hand, in CLD patients, significant associations of IgG RF and the serum
IgG concentration, and of IgM RF and the serum IgM concentration, were observed. These results indicated that IgA RF in active
RA is the most characteristic RF isotype distinguishing it from other nonrheumatic diseases, as well as from inactive RA.
RF isotypes reflected the background polyclonal B-cell activation in different manners in both diseases. In CLD, RF isotypes
seemed to be disease-related immunological disorders reflecting disease progression.
Received: February 17, 2000 / Accepted: July 5, 2001 |
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Keywords: | Chronic liver diseases (CLD) Isotypes Rheumatoid arthritis (RA) Rheumatoid factors (RFs) |
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