The synovial membrane in osteoarthritis: a histological study including the characterisation of the cellular infiltrate present in inflammatory osteoarthritis using monoclonal antibodies.

Inflammatory infiltration of the synovial membrane has been described in a proportion of cases of osteoarthritis (OA). Using conventional histology, lymphoid follicles, diffuse fibrosis, and perivascular fibrosis were shown to be present to a significantly greater extent and in more synovial membranes in osteoarthritis than in those cases where there was a mechanical or traumatic background to the joint disease. Calcium pyrophosphate dihydrate crystals (five patients) and detritus fragments of bone and cartilage (seven patients) were present in small numbers of the total cases of OA (38) studied. Neither of these features was related to the presence of an inflammatory infiltrate. Examination of 20 osteoarthritic synovial membranes using monoclonal antibodies showed the presence of lymphoid follicles containing T helper and T suppressor lymphocytes, B lymphocytes, and macrophages expressing HLA-DR in five cases. The T helper:suppressor ratio varied between 1:1 and 2.5:1 in these follicles. In addition, half of the OA samples, including these five cases, showed the presence of a diffuse cellular infiltrate containing T and B lymphocytes and macrophages, which were HLA-DR positive. Granulocytes were present in this diffuse infiltrate in those cases containing lymphoid follicles. The results confirm the presence of an inflammatory form of osteoarthritis but also show that the proportions of lymphoid cells are not the same as those considered to be typical of rheumatoid arthritis.

Demonstration of antiglobulin activity in the synovial membrane of patients with rheumatoid arthritis and ankylosing spondylitis after pepsin treatment: real or artefact?

The results of immunofluorescence studies in nine cases of rheumatoid arthritis and nine cases of ankylosing spondylitis are presented. Antiglobulin activity was sought with fluorescein labelled, heat aggregated human IgG and rabbit immunoglobulin (indirect immunofluorescence). A similar degree of increased staining for rheumatoid factor activity was seen after pepsin digestion in all cases of rheumatoid arthritis and three of the ankylosing spondylitic cases. This staining for rheumatoid factor could also be shown in control tissue after pepsin digestion, suggesting that the enhanced staining was an artefact.

Immunoglobulin classes in plasma cells of the synovial membrane in chronic inflammatory joint disease.

The histological features of the synovial membrane in rheumatoid arthritis (RA) are shared by other chronic inflammatory joint diseases, so that diagnostic differentiation is impossible. Examination of the immunoglobulin class in the plasma cells present in inflamed synovial membranes, however, has shown differences. Synovial membranes from 12 patients were seropositive RA, eight with seronegative RA, eight with ankylosing spondylitis, five with psoriatic arthritis, and three with Reiter's syndrome have been compared by peroxidase-antiperoxidase (PAP) staining for immunoglobulin classes on routinely paraffin wax embedded sections. There were no significant differences in the percentages of plasma cells containing IgG of IgA between the diseases studied. There were, however, significantly more plasma cells containing IgM in patients with seropositive RA (2-34%) compared with those with seronegative RA (0-10%; p less than 0.002) and with other chronic synovitides (0-9%; p less than 0.002). The results show that it is possible to distinguish seropositive RA from other chronic inflammatory joint diseases by PAP staining for immunoglobulin classes in the plasma cells present in the inflamed synovial membrane.

Immunohistochemical analysis of mononuclear cell subsets in inflammatory and non-inflammatory myopathies.

Immunohistochemical procedures were used to analyse the subpopulations of mononuclear cells in muscle biopsies from 24 patients with polymyositis. The character of the cellular infiltrate was similar at the perivascular, perimysial, and endomysial sites, with cytotoxic-suppressor T lymphocytes (T8+) and macrophages being the dominant elements. Helper T lymphocytes (T4+) and B lymphocytes were present in smaller numbers. A control series of 17 muscle biopsies from normal subjects and patients with non-inflammatory myopathies and neurogenic conditions was also studied: the numbers of mononuclear cells present were much smaller than in polymyositis, but the ratio of T4:T8 lymphocytes was similar to that found in biopsies affected by polymyositis. We conclude that both cytotoxic-suppressor T lymphocytes and macrophages are important in the pathogenesis of inflammatory myopathy.

Fibronectin in the synovium of chronic inflammatory joint disease.

The localisation of fibronectin in the synovial membrane of rheumatoid arthritis (RA) and other chronic inflammatory joint diseases has been studied using a peroxidase-antiperoxidase immunohistochemical method. Synovia were studied from seven cases of seropositive RA three cases of seronegative RA, six cases of ankylosing spondylitis, four cases of Reiter's syndrome and five of psoriatic arthritis. Six were small biopsies and the remaining tissues were obtained at open surgery for orthopaedic procedures or biopsies. Fibronectin was demonstrated in all of the synovia examined and was present in intimal cells, synovial giant cells, the walls of small blood vessels, basement membrane of larger vessels and deposits of fibrin. No difference in this distribution of fibronectin was found in seropositive and seronegative RA, ankylosing spondylitis, Reiter's syndrome or psoriatic arthritis, neither was there any difference in the amount of fibronectin at various sites.

Histopathology of the synovial membrane of peripheral joints in ankylosing spondylitis.

The histological features of the synovial membrane of peripheral joints in ankylosing spondylitis are similar to those seen in rheumatoid arthritis. There is intimal cell hyperplasia, a diffuse lymphocyte and plasma cell infiltrate, and formation of lymphoid follicles. Peroxidase-antiperoxidase staining shows the presence of IgG-, IgA-, and IgM-containing plasma cells in ankylosing spondylitis. The percentage of IgM-containing cells is significantly lower in ankylosing spondylitis than in rheumatoid arthritis.