Protein synthesis in rheumatoid synovial tissue

Two-dimensional electrophoresis of synovial tissue, synovial fluid and serum in patients with rheumatoid arthritis and related diseases

Using the technique of two-dimensional (2D) electrophoresis with consecutive silver staining, we investigated samples of serum, synovial fluid and synovial tissue obtained from 19 patients suffering from rheumatoid arthritis (RA) or non-RA arthritis. From these experiments we have drawn the following conclusions. 2D electrophoresis of serum, synovial fluid and synovial tissue extracts taken from patients suffering from joint diseases is a reproducible method. Repeated runs of the same sample reveal an essentially constant protein spot pattern. The time period between surgery and tissue preparation did not influence the number of protein spots when less than 15 h was involved. The protein spot number is always lower in synovial fluid than in either synovial tissue or serum in RA and non-RA patients. The mean value for the number of spots is 68 for the inflamed tissue irrespective of the cause of arthritis (RA and non-RA group taken together) and 47 for the control group. This difference is significant. We were able to definitely identify 7 spots in the tissue extract. We did not find RA-specific protein spots in either serum, synovial fluid or tissue extracts from the synovial membrane. The only significant difference between RA patients and either non-RA or control group patients concerning the protein spot pattern is the increased size of the immunoglobulin spot (mainly IgG) in RA. In addition, we discuss possible reasons for failure of the 2D electrophoresis technique to detect disease-specific protein patterns.

In situ evaluation of immunoglobulin synthesis of synovial plasma cells in rheumatoid arthritis and osteoarthritis by plug photometry

Synovial membranes of patients with osteoarthritis--a disease with unaltered immunoregulation--and rheumatoid arthritis were immunostained for the different immunoglobulin isotypes using the PAP-method and a two-layer alkaline phosphatase technique. Randomly selected plasma cells with positive immunostaining were measured by plug photometry. The average extinction of the single plasma cell is considered to be indicative of the immunoglobulin synthesis of the measured plasma cell and the isotype under study. When we compared both disease entities, patients with rheumatoid arthritis were characterized (i) by higher average extinction values for all Ig-isotypes except IgG (ii) by a higher rate of high producer plasma cells. From this data, we conclude that immunophotometry is a new in vivo method for discriminating two types of synovitis (i) one without increased Ig-synthesis at the single cell level and (ii) a second one with increased Ig-synthesis.

Synthesis of antibodies, including antiviral antibodies, in the knee joints of patients with arthritis

Serum and synovial fluids from 16 patients with seronegative arthritis and eight with rheumatoid arthritis were studied for immunoglobulin levels and for antibody levels to five viruses. When allowances were made for the distribution of immunoglobulins between serum and synovial fluid there was evidence that in several patients antibody to one or more viruses was synthesised locally in the joint. IgG and especially IgM were present in greatly increased amounts in arthritic joints compared with normal joints. On the basis of serum/synovial fluid ratios inflammation and local immunoglobulin synthesis are discussed as possible causes. These results are compared with antiviral antibody and immunoglobulin ratios observed in the serum and cerebrospinal fluid of patients with multiple sclerosis.

Mapping of proteins from cultured fibroblasts of synovial and subcutaneous origin by high resolution two-dimensional polyacrylamide gel electrophoresis

Nine different cell lines of human (A) rheumatoid and (B) normal synovial fibroblasts and of (C) normal skin fibroblasts were obtained from tissue explants and grown as monolayers. The cellular protein synthesis was studied by high resolution two-dimensional polyacrylamide gel electrophoresis. Between the fourth and 10th passage of the cells in culture apparently no consistent differences were found which could be ascribed to the origin of the cells, to the rheumatoid state of the synovial tissue, or to the increasing age of the cultured fibroblasts.

Clonally restricted anti-IgG antibodies in rheumatoid arthritis

Clonally restricted anti-IgG antibodies were detected, by isoelectric focusing (IEF) and chromatofocusing techniques, in the sera of patients with rheumatoid arthritis (RA). Anti-Fab antibodies were predominantly acidic proteins with isoelectric points of 4.5-6.5 and displayed restricted spectrotype patterns. Proteins reactive with the Fc portion of IgG showed polyclonal spectrotype patterns with alkaline pI of 7.5-9.0. A limited array of anti-Fab spectrotypes was consistently detected in RA sera when analyzed by IEF on 6M urea gels. Additional anti-Fab antibody bands were detected when the RA sera were dialyzed against 4-6M urea prior to IEF analysis, indicating that some anti-Fab antibodies exist in a complexed form in serum. Under these dissociating conditions, anti-Fab antibodies could also be detected in normal subjects, but the spectrotype patterns were more restricted than those in RA sera. Because anti-Fab antibodies may regulate normal immune responses, the increased quantity of clonally restricted anti-Fab antibodies in RA may indicate an abnormality of this immunoregulation.

Pronounced production of polyclonal immunoglobulin G1 in the synovial fluid of goats with caprine arthritis-encephalitis virus infection

Infection of goats with caprine arthritis-encephalitis virus, a lentivirus, resulted in arthritis characterized by the production of intrasynovial immunoglobulin G1 concentrations that were 2 to 5.3 times the serum concentrations in the inoculated carpi at 6 months postinoculation. The intrasynovial immunoglobulin was polyclonal, and its presence was accompanied by increased albumin leakage into the joints. Synovial fluid immunoglobulin levels fluctuated temporally but remained elevated compared with medium-inoculated controls for 38 months after infection. Elevated immunoglobulin G1 concentrations correlated with focal sublumenal plasmacytic infiltrates in the synovia of inoculated carpi at 5 months postinoculation. Inflammation in the uninoculated joints of infected goats was also accompanied by increased intrasynovial immunoglobulin G1 levels. Antibody to systemically administered antigens was a greater proportion of the immunoglobulin population in sera than in synovial fluids of infected goats, suggesting that antibody production to local antigens was responsible for increased intrasynovial immunoglobulin G1 levels.