The effect of menadione epoxide on the experimental immune arthritis in the rabbit.

It was shown previously that the experimentally induced arthritis in the rabbit can be largely nullified by subsequent treatment with menadione (by gavage). It is now shown that menadione epoxide, as is produced in the vitamin K cycle, also exerts a beneficial effect histologically and biochemically. Such treatment decreased both the glucose 6-phosphate dehydrogenase and the 6-phosphogluconolactonase activities in the synovial lining cells of the challenged joints towards values found in the unchallenged joints; it had only equivocal effects on the 6-phosphogluconate dehydrogenase activity. The results indicated that the epoxide might be interfering primarily with the lactonase activity.

Amelioration by menadione of the experimental chronic immune arthritis in the rabbit.

The immunological induction of arthritis in the knee of the rabbit is well established as a model for human rheumatoid arthritis. It has the special advantage of allowing the development of the condition, and the effect of disease-modifying agents, to be followed. Attention has been focussed on the activity of glucose 6-phosphate dehydrogenase in the synovial lining cells since the fourfold elevation of this activity was shown to be fundamental in the human condition. An equal elevation of this activity has now been demonstrated in the rabbit model. Furthermore, it has been shown that the oral administration of menadione decreases this activity towards normality with a concomitant decrease in the degree of inflammation.

The origin of the apparent synovial lining cell hyperplasia in rheumatoid arthritis: evidence for a deep stem cell.

The experimental model of inflammatory arthritis in the rabbit has been used to study the possible origin of the apparent synovial lining cell hyperplasia. A small amount of 3H-thymidine was injected into the joints and the fate of the labelled cells investigated by autoradiography. At times up to 24 h after the injection, most of the labelled cells occurred in the sub-lining region; this proportionality was reversed when the joints were sampled at later times. These results indicate that at least much of the increase of synovial lining cells may be derived from cells from deeper in the synovial tissue which move to the synovial surface.

Decreased inhibition of proteolysis by osteoarthritic synovial fluids.

The hypothesis, that part of the pathogenesis of osteoarthritis may be due to the diminished ability of the osteoarthritic synovial fluid to restrict proteolysis, has been tested by a functional biochemical assay for such inhibitory activity. The results from six synovial fluids from normal or mildly osteoarthritic knees were compared with those from seven from joints showing moderately severe or severe osteoarthritis. Whether on the basis of 'per mg protein' or 'per millilitre' of the fluids, the latter showed a clearly diminished capacity for inhibiting proteolysis under the conditions of this assay.

Cell division in the synovial lining in experimental allergic arthritis: proliferation of cells during the development of chronic arthritis.

The synovial tissue in experimentally induced immune arthritis induced in the rabbit has been used as a model of rheumatoid arthritis to determine which cells may contribute to the growth of this tissue. Tissue from the challenged and from the unchallenged knee joints was taken, after the intra-articular injection of a small amount of tritiated thymidine, from rabbits up to 3 months after the arthritis was induced. DNA synthesis, as a measure of cell proliferative activity, was assessed firstly by measuring the labelling index in autoradiographs of sections of such tissue, and secondly by the DNA synthetic index obtained by Feulgen cytophotometry. These measurements were made separately on synoviocytes, on the structural cells of the stroma, on the cells lining the small blood vessels, and on the infiltrating inflammatory cells. The DNA synthetic activity of the synoviocytes, and of the stromal noninflammatory cells, was maximal between 3 and 7 days after challenge. The activity in the synoviocytes, in particular, remained raised for up to 84 days after the challenge. Thus these cells appear to be capable of contributing to the hyperplasia, but the contribution of other cells, deeper in the stroma, cannot be excluded.

Experimental allergic arthritis in the rabbit: alterations in the cellularity and the rate of cellular proliferation in the synovial linings of the challenged joints of rabbits immunized with antigen in Freund's incomplete adjuvant.

Rabbits have been immunized with ovalbumin in Freund's incomplete adjuvant (FIA) followed by the intra-articular injection of ovalbumin, in order to follow the development of inflammation in the synovial lining. The kinetics of cell proliferation have been investigated using tritiated thymidine (3HTdR) autoradiography and Feulgen cytophotometry. Unexpectedly, marked histological changes were found in the synovium, with hyperplasia of synoviocytes, and of the connective-tissue cells of the subintima, being seen as early as 3 days after challenge. Large numbers of inflammatory cells, including many plasma cells, were found in the synovium at between 5 and 11 days. Labelling of synoviocytes and connective-tissue cells reached a maximum at 3 days and declined thereafter, reaching normal levels at 14 days. Three weeks after challenge the synovium was normal in appearance.

Evidence for cell division in synoviocytes in acutely inflamed rabbit joints.

DNA synthesis has been measured both by Feulgen cytophotometry, quantified by the DNA synthesis index, and by tritiated thymidine autoradiography, quantified by the labelling index. In the early acute inflammation resulting from the intra-articular challenge of ovalbumin in sensitised rabbits both indices rose considerably, so that at least 1 in 10 synoviocytes was heavily labelled 3 days after challenge. The results are compatible with the concept that even such apparently differentiated synoviocytes are capable of cell division.

Metabolic alterations in the synoviocytes in chronically inflamed knee joints in immune arthritis in the rabbit: comparison with rheumatoid arthritis.

The metabolism of the synovial lining cells of the normal and chronically inflamed joints of rabbits, in the Dumonde and Glynn model of rheumatoid arthritis, has been examined by quantitative cytochemistry. Significant alterations in metabolic activity were found in the synovial lining cells of the chronically inflamed joints. These alterations in metabolic activity closely resemble the pattern of metabolic changes found in human synovial lining cells in rheumatoid arthritis.

Cell-mediated and humoral immunity to chick type II collagen and its cyanogen bromide peptides in guinea-pigs.

Cell-mediated immunity (CMI) to chick type II collagen and its cyanogen bromide (CB) peptides was studied in guinea-pigs using cutaneous delayed hypersensitivity reactions. Responses were largely independent of molecular conformation in animals immunized with either native or denatured collagen, and reactions obtained with CB peptides 8, 9, 10 and 12 suggested that sites in the central regions of collagen chains were recognized in CMI. Antibodies to collagen were detected by haemagglutination and immunofluorescence only in animals immunized with native molecule and not in animals immunized with denatured or CB-digested material. Humoral and CMI responses were similar in that neither recognized the pepsin-labile non-helical regions of the molecule. The responses differed in that humoral reactions were conformation-dependent and type-specific and CMI reactions were not.

Effect of excising Freund's adjuvant granuloma on subsequent development of experimental allergic arthritis.

Rabbits were immunized with antigen in Freund's complete adjuvant. Several weeks later the granuloma which developed was excised one day before joint challenge with antigen. The subsequent development of experimental allergic arthritis (EAA) was not affected, which argues against the chronicity of the disease being maintained by continuous recruitment of mycobacterial debris to EAA joints.

The role of the plasmalogen in the cross-reaction between group A streptococcus and human myocardium.

Ethanol-soluble mycardial material which reacts with anti-streptococcal sera in a number of immunological tests has been isolated and identified as ethanolamine plasmalogen. The reactions of cardiac plasmalogen with antistreptococcal sera was specific and could be inhibited by streptococcus-derived materials. Guinea-pigs sensitized to streptococci gave positive skin reactions when challenged with myocardial plasmalogen. The pattern of the immunofluorescent staining given by antiplasmalogen sera was very much like that given by antistreptococcal sera. Nevertheless, the plasmalogen failed to compete for tissue-bound myocardial antigens when tried as an inhibitor of the immunofluorescent staining of myocardium either by antistreptococcal sera or by antiplasmalogen sera. A hypothesis of the role of the plasmalogen in the formation of complexes between streptococci and myocardium-derived material in the initiation of autoimmune processes is presented.

Primary lesion in osteoarthrosis.

The primary disturbance in osteoarthrosis is generally regarded as occurring in the articular cartilage and as resulting from a combination of ageing and mechanical factors. An alternative hypothesis is that the primary disturbance is located in the synovial lining cells. It is suggested that proteolytic enzymes which normally leak from the phagocytic (A type) lining cells are in the healthy joint neutralised by inhibitors synthesised by the B-type lining cells. Osteoarthrosis is the result of an imbalance between leakage of enzymes and provision of inhibitors.

Is persisting antigen responsible for the chronicity of experimental allergic arthritis?

Animals were injected intra-articularly with antigen after prior immunization with that antigen in Freund's incomplete adjuvant in order to precipitate immune complexes in the surfaces of menisci, ligaments, and cartilage. On reimmunization with antigen in Freund's complete adjuvant 10 weeks later, generally an arthritis limited to the intercondylar fossa developed; but on intra-articular injection of antigen a second time a widespread arthritis developed in that joint. Thus immune deviation had not occurred and animals were in an immunological condition such as to be capable of developing widespread arthritis given the correct intra-articular stimulus. It is concluded that antigen, persisting as immune complexes, plays no part in maintaining widespread monarthritis, presumably owing to its inability to participate in a delayed hypersensitivity reaction as a result of sequestration.

Anti-streptococcal antibodies reacting with brain tissue. I. Immunofluourescent studies.

Serum JD from a 14-year old girl with Sydenhams chorea contained antibodies which gave immunofluorescent staining of the limiting membrane of the brain, ependymal tissue and fibrous astrocytes. These antibodies could be completely absorbed by Str. pyogenes type 24 (NCTC 8305) but only partially if at all by type 6 matt (NCTC 8302) or type 6 glossy (NCTC 8709). In contrast, staining by the same serum of the choroid plexus, the periphery of hepatocytes, the periphery of the cells of the gastric mucosa, and tubules in the kidney could be absorbed out by the type 6 matt and type 24 strains (but not by the type 6 glossy or Staph. aureus NCTC 6571). A rabbit anti-streptococcal serum (3/74) raised against disintegrated washed cells of Str. pyogenes type 24 stained and the same structures in the brain to high titre, but not the choroid plexus and not the other structures stained by serum JD. These staining reactions of 3/74 could be absorbed out by Str. pyogenes type 24 but not by Str. pyogenes type 6 matt or type 6 glossy. None of these staining patterns given by serum JD or by 3/74 could be absorbed by human uterine smooth muscle. Serum 3/74 stained heart muscle but this reaction could be absorbed without affecting the brain staining reactions. Sera from 4 other patients with Sydenham's chorea were found to give staining of the ependyma and the limiting membrane, 2 only very weakly.