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G Panayi

Publications and source records attributed to G Panayi.

34 records · Page 2Linked to original sources
PubMed1988

The preferential accumulation of helper-inducer T lymphocytes in inflammatory lesions: evidence for regulation by selective endothelial and homotypic adhesion.

The mechanisms which lead to the accumulation of T lymphocytes into inflammatory lesions are not clearly understood. We have previously shown that synovial CD4 T lymphocytes are mostly CDw29+UCHL1+ (helper-inducer cells) and very few carry the CD45R antigen which identifies the suppressor-inducer subset. Synovial CD8+ cells are also CDw29+UCHL1+CD45R-. In the present study, lymphocytes from pleural and peritoneal inflammatory infiltrates were shown to have a similar phenotypic pattern. Furthermore, it was demonstrated that the CDw29+UCHL1+ subset had a greater ability than CD45R+ cells to adhere to endothelial cells and to form homotypic clusters. Differential surface expression of LFA-1 on the two subsets was also shown, but this could not account for the demonstrated adhesion differences. Differences in adhesion between CDw29+/UCHL1+ and CD45R+ cells may explain the preferential accumulation of CDw29+/UCHL1+ cells in inflammatory infiltrates and underlie some of the functional differences between cells taken from sites of chronic inflammation and those from peripheral blood.

Antigens, Differentiation↗
PubMed1987

Abnormal distribution of the helper-inducer and suppressor-inducer T-lymphocyte subsets in the rheumatoid joint.

T lymphocytes can be divided into two main phenotypic populations, CD4 and CD8. These can be further subdivided into 2H4, 4B4, or UCHL1 subsets by appropriate monoclonal antibodies. We have investigated these subsets in the synovial fluid of patients with rheumatoid arthritis and have found (i) a virtual absence of CD4+ 2H4+ and the marked reduction of CD8+ 2H4+ T cells; (ii) a marked increase of CD4+ 4B4+ and CD8+ 4B4+ T cells; and (iii) a marked increase of CD4+ UCHL1+ and CD8+ UCHL1+ T cells compared with peripheral blood. Although the functions of the CD8 subsets are not known, the virtual absence of CD4+ 2H4+ suppressor-inducer T cells and the marked increase of CD4+ 4B4+ helper-inducer T cells and of CD4+ UCHL1+ memory T cells may help to explain the many known functional immunological properties of synovial T cells.

Antibodies, Monoclonal↗
PubMed1985

Differential dosing study of pirazolac, a new non-steroidal anti-inflammatory agent, in patients with rheumatoid arthritis.

Twenty-four patients with classical or definite rheumatoid arthritis participated in a 4-week double-blind crossover study to compare the effectiveness of two different dosage regimens of pirazolac. Patients were allocated at random to receive 2-weeks' treatment with either 300 mg pirazolac in the morning and 600 mg at night or 450 mg pirazolac given morning and evening, and were then crossed over to the alternative regimen for a further 2 weeks. Physician assessments of disease activity were carried out on entry and at the end of each treatment period, and patients kept a daily record of visual analogue scale scores for pain and stiffness. The results showed that both dosage regimens of pirazolac produced a significant improvement in the parameters assessed, but the difference between the two regimens was not significant. However, overall assessment at the end of the trial by the 23 patients who completed the study showed that 14 preferred the 300/600 mg regimen compared with 7 who preferred the 450/450 mg regimen: 2 patients considered both regimens equally effective. Pirazolac was relatively well tolerated, only a few patients reporting gastro-intestinal (2) and skin (3) side-effects during the trial period.

Adult↗
PubMed1984

Mechanisms of depressed delayed-type hypersensitivity in rheumatoid arthritis: the role of protein energy malnutrition.

The presence of anergy and its relationship to malnutrition was investigated in patients with rheumatoid arthritis (RA) and in controls. A generalised reduction in delayed cutaneous hypersensitivity to 7 recall antigens were found in 104 RA patients compared with 67 controls. No measured of the disease was capable of predicting cutaneous anergy, which was present in 36% of patients but none of the controls. A detailed dietary assessment in 30 RA patients and 30 controls revealed little evidence of clinically important malnutrition. It is therefore concluded that the cutaneous anergy of rheumatoid arthritis is not a consequence of nutritional factors.

Adult↗
PubMed1984

HLA-B27 and the immune response to enterobacterial antigens in ankylosing spondylitis.

Total serum immunoglobulins and class specific serum antibodies to Klebsiella pneumoniae, Salmonella typhimurium, Yersinia enterocolitica and Pseudomonas aeruginosa were measured in 107 patients with ankylosing spondylitis (AS) and 110 healthy tissue typed controls by enzyme linked immunosorbent assay (ELISA). The specificity of this technique was confirmed by the use of specific bacterial murine antisera and by cross-absorption of human sera by specific bacteria. Total serum IgA in AS patients correlated with both erythrocyte sedimentation rate (ESR) (P less than 0.001) and C-reactive protein (P less than 0.05) and was significantly elevated compared to healthy individuals (P less than 0.001). A significant elevation of IgA antibodies to K. pneumoniae was detected in the serum of AS patients with active disease when compared to healthy controls (P less than 0.01). These studies support the involvement of an enterobacterial micro-organism in the pathogenesis of AS and further relate to the role of HLA-B27 in this disease.

Antibodies, Bacterial↗
PubMed1983

The involvement of interdigitating (antigen-presenting) cells in the pathogenesis of rheumatoid arthritis.

Macrophage like cells expressing high concentrations of HLA-DR antigen have been identified in situ within the synovium of patients with rheumatoid arthritis. The characteristics of these cells have been determined using immunohistological analysis and combined cytochemical techniques. It was found that the majority (greater than 80%) of these cells were interspersed within the perivascular lymphocytic infiltrates occurring in the synovium. These cells did not stain with antisera against surface immunoglobulin or any Mc Abs to T lymphocyte markers. Further combined staining demonstrated that the HLA-DR + ve cells did stain with an anti-monocyte monoclonal (FMC-17), but could not be stained with a Mc Ab against C3b receptors. The interfacing of cytochemical reactions for acid phosphatase (ACP) and adenosine triphosphatase (ATPase) with immunofluorescence staining for HLA-DR demonstrated that these cells were ACP - ve ATPase + ve. This analysis led to the conclusion that the HLA-DR + ve cells found in abundance in the rheumatoid synovium expressed identical characteristics to the interdigitating cells of the normal lymph node paracortex. The possible significance of the presence of large numbers of such antigen presenting cells in the rheumatoid synovium is discussed.

Acid Phosphatase↗
PubMed1982

Histochemical discrimination of HLA-DR positive cell populations in the normal and arthritic synovial lining.

A combination of immunochemical staining for HLA-DR antigens and the histochemical demonstration of enzyme activity has been used to identify specific cell populations in the normal and arthritic synovial lining layers. Such combined staining has revealed that the normal synovial lining contains a proportion of HLA-DR + ve cells, all of which show strong lysosomal enzyme activity. This population is greatly expanded in biopsies from patients with osteoarthritis and these positive cells also express strong ATPase activity. In the rheumatoid synovium five distinct cell types can be identified; all of which are HLA-DR + ve but differ in their morphology and pattern of enzyme activity. Of special interest was the discovery that a small but significant proportion of these cells have the characteristics of the interdigitating cells of the lymph node paracortex. The relationship between the emergence of these heterogeneous populations and the immunological basis of this inflammatory response is discussed.

Acid Phosphatase↗
PubMed1982

T cell subset abnormalities in tissue lesions developing during autoimmune disorders, viral infection, and graft-vs.-host disease.

The authors review a large body of contemporary immunohistologic findings on the tissue distribution of T lymphocytes in normal and pathological conditions. The suggestions for technological advances in this field are: signal amplification using mixtures of monoclonal antibodies directed against different epitopes on the same antigen (e.g. OKT4A+B+D), triple layer amplification systems using hapten-labelled antibodies, and informative double staining methods with combinations of antibodies labelled with different fluorochromes or enzymes. Review of histological observations in a series of human diseases suggests that imbalances of OKT4+ and OKT8+ subsets of T lymphocytes may represent different types of immunoregulatory disorders. Rheumatoid arthritis and sarcoidosis appear to involve a high level of OKT4+ subpopulation response coupled with an associated appearance of a special type of HLA-DR+ macrophages. It remains to be seen whether normal or self-limited immunological responses (early stages of bacterial infection or delayed-type hypersensitivity reactions) produce OKT4+ and macrophage responses that are characteristically different. Meanwhile, excessive levels of OKT8+ cells have been found in a wide range of recognized or presumed immunoregulatory disorders including: graft-vs.-host reaction and viral infections. These disorders, as well as primary biliary cirrhosis and lichen planus, appear to possess both overlapping and disparate clinical characteristics, and the immunohistological observations may reflect the functional heterogeneity of OKT8+ populations in these diseases. These studies show that histologically meaningful heterogeneity can already be demonstrated for the OKT8+ lymphocyte group.

Animals↗
PubMed1981

Rheumatoid arthritis: a disease of T-lymphocyte/macrophage immunoregulation.

In rheumatoid arthritis the synovial membrane has many of the characteristics of a hyperactive, immunologically-stimulated lymphoid organ. The basis of this hyperactivity is poorly understood. Highly specific antisera to human Ia-like (HLA-DR) antigens and monoclonal antibodies (OKT series) to various T-lymphocyte subsets were used to analyse both the normal and the rheumatoid synovium and to compare it with normal lymph nodes. In rheumatoid arthritis the synovium acquires an infiltrate with microanatomical similarities to the paracortical area of the lymph node. Large, very strongly HLA-DR-positive macrophage-like interdigitating cells form close contacts with the OKT4+ (inducer-type) T-cells, while the OKT8+ population (T-cells of suppressor-cytotoxic type) between the macrophage-OKT4+ cell clusters is scanty (T4/T8 ratio = 9:1). By contrast, in the lymph node there are more OKT8 T-cells interspersed between the HLA-DR+ interdigitating cells and OKT4+ cells (T4/T8 ratio = 2:1). The large interdigitating cells and the OKT4+ T-cell population may be mutually stimulatory. In the absence of efficient suppression this stimulation may lead to activation of B-lymphocytes and oligoclonal or polyclonal immunoglobulin synthesis, as is found in the synovial membrane in rheumatoid arthritis.

Antibodies, Monoclonal↗
PubMed1980

Ankylosing spondylitis, HLA-B27 and Klebsiella. I. Cross-reactivity studies with rabbit antisera.

Sera from rabbits immunized with HLA-B27 lymphocytes showed increased activity against klebsiellal enterobacter antigens using immunodiffusion, bacterial agglutination (P less than 0.025), haemagglutination (P less than 0.001) and radiobinding assays (P less than 0.001). Immunoprecipitin lines were also produced by these antilymphocyte sera against extracts from Yersinia enterocolitica and Shigella sonnci microorganisms. Rabbit anti-klebsiella sera had lymphocytotoxic activity against HLA-B27 lymphocytes obtained from patients with ankylosing spondylitis (P less than 0.001). These results suggest partial cross-reactivity between some antigens found in several Gram-negative microorganisms and HLA-B27 lymphocytes.

Agglutination Tests↗
PubMedDate not supplied

[Role of cell migration in the pathogenesis of rheumatoid arthritis: in vivo studies in SCID mice transplanted with human synovial membrane].

OBJECTIVE: Adhesion mechanisms play a central role in the recruitment of leukocytes which characteristically infiltrate rheumatoid synovium. Therefore, we adapted an animal model, in which human rheumatoid synovium was transplanted into severe combined immunodeficient (SCID) mice, to study the effects of Tumor Necrosis Factor-alpha (TNF-alpha) in modulatine leukocyte migration and to investigate the chemotactic potential of Stromal Derived Factor-1 alpha (SDF-1 alpha). MATERIALS AND METHODS: Human synovium samples, obtained from patients undergoing joint replacement, were divided into two parts. One was analysed by immunohistology and the other was implanted subcutaneously into SCID mice under general anaesthesia. Four weeks post-transplantation, grafts were injected with optimal dose of SDF-1, TNF-alpha or saline (negative control). At the same time, animals were injected iv with fluorescently labelled cells. 48 hours later mice were sacrificed and grafts removed for cryo-hystology. The number of cells migrating to the grafts was determined by UV-microscopy and the results expressed as cells per high power field. RESULTS AND CONCLUSIONS: In these studies we provide the evidence that: 1) the animal model, in which human tissues are grafted into SCID mice, can be used to study cell migration under controlled experimental conditions; 2) direct intragraft injection of TNF-alpha increases lymphocytes migration and up-regulates the expression of human adhesion molecules (CAMs) and 3) SDF-1 alphainjected intragraft increases the migration of the pro-myelo-monocytic U937 cells to synovial transplants, even more efficiently than TNF-alpha, but without modifications of CAMs' expression.

Animals↗
PubMedDate not supplied

Mechanisms of action of second-line agents and choice of drugs in combination therapy.

Second-line agents are used commonly for the treatment of rheumatoid arthritis (RA). They suppress inflammation and ameliorate symptoms but often fail to substantially improve long-term disease outcome. Their use in RA was discovered serendipitously and their modes of action were largely unknown. Recent researches have identified some of their mechanisms of action. Most of them have antiinflammatory properties and some are immunomodulators. Traditionally, second-line agents are used as monotherapy, but recent evidence suggests that combination treatment with two or more drugs may be more efficacious. However, the choice of agents in combination therapy is not based on their mechanisms of action. We review current knowledge on the modes of action of second-line agents and assess whether such understanding may offer a rational basis for combination therapy.

Antirheumatic Agents↗