A. Whelan

Synovial tissue macrophages and joint erosion in rheumatoid arthritis.

OBJECTIVES--To analyse the mononuclear cell populations in synovial membrane biopsies obtained before treatment from patients with rheumatoid arthritis (RA) and to correlate the findings with the degree of joint damage occurring over one year. METHODS--Multiple needle biopsy specimens were obtained from inflamed knee joints on entry to the study. The tissue samples were examined using immunohistochemical techniques. The degree of joint damage was estimated using the Larsen radiological index. RESULTS--Twelve patients were studied. It was observed that there was a significant correlation between the number of synovial tissue macrophages and the degree of joint erosion over one year (r = 0.66; p = 0.04). The synovial lining layer contained large numbers of macrophages and the cellularity of the lining layer correlated significantly with the number of macrophages infiltrating the sublining areas (r = 0.65; p = 0.01). Finally, the cellularity of the lining layer correlated with the synovial fluid levels of interleukin-6 (r = 0.66; p = 0.04). The radiological course did not correlate with infiltrating T or B lymphocyte populations, but did correlate with other previously identified indicators of the clinical course, including a high index of disease activity and IgA rheumatoid factors levels. CONCLUSION--This study suggests that synovial tissue macrophages play a critical role in the pathogenesis of joint erosion in RA.

Correlation of platelet FcγRIIA polymorphism in refractory idiopathic (immune) thrombocytopenic purpura

FcγRIIA, a low affinity receptor for IgG, is a polymorphic molecule: FcγRIIA‐HH131, FcγRIIA‐HR131 and FcγRIIA‐RR131. This polymorphism influences the efficiency of the receptor to bind with IgG2. Recent reports on altered distribution amongst individuals with heparin‐induced thrombocytopenia (HIT) prompted us to examine the FcγRIIA polymorphism in a cohort of patients with refractory idiopathic (immune) thrombocytopenic purpura (ITP), in whom severe disease had required them to undergo splenectomy. 29 post splenectomy ITP individuals and 61 normal controls were investigated. Polymerase chain reaction (PCR) and a Southern blotting technique were used to determine the FcγRII polymorphism. Although the distribution of the allotypes of FcγRIIA in the control population was similar to that found in other European studies of Caucasian populations (15 (25%) HH131; 35 (57%) HR131; 11(18%) RR131), the patient group was skewed towards the RR131 allotype which has least efficiency for IgG2 binding (3 (10%) HH131; 12 (42%) HR131; 14 (48%) RR131; P < 0.005). These findings suggest that FcγRIIA polymorphisms may be implicated in the pathophysiology of ITP or may be responsible for modulating the immune response in this heterogenous autoimmune disease.

Analysis of cell populations in rheumatoid arthritis synovial tissues

Knee synovium, taken from patients with rheumatoid arthritis at the time of arthroplasty, was studied immunohistologically. Focal perivascular lymphoid infiltrates of different sizes were examined in detail to evaluate changes in cell populations as the infiltrate size increased. T cells formed the largest component of mononuclear cells of all aggregates. The large grade 3 aggregates contained substantial numbers of B cells arranged around a central venule and cells bearing the CD45RA+ phenotype. In contrast, the small grade 1 aggregates contained few B cells and the T-cell population contained relatively greater numbers of CD8+ cells. Cells bearing the CD45RO+ phenotype exceeded CD45RA+ cells in grade 1 aggregates. Detailed analysis of mononuclear cell aggregates of different sizes in the rheumatoid synovium suggests that the composition of each aggregate depends on the total number of mononuclear cells it contains.

Immunohistological analysis of the synovial membrane: search for predictors of the clinical course in rheumatoid arthritis.

Immunohistological features which might predict the clinical course and outcome of rheumatoid arthritis were sought by examining multiple synovial membrane samples obtained by needle biopsy from the knee joints of 57 patients who had not received disease modifying antirheumatic drugs. Clinical measurements, but not biopsies, were repeated one year and three years after starting treatment. A correlation between both the intensity of synovial lining layer thickening and mononuclear cell infiltration and the clinical status at the time of biopsy was seen. After three years of treatment the correlations were maintained in patients who had presented and persisted with milder disease but not in patients who had presented with more active disease.

Contrasting levels of in vitro cytokine production by rheumatoid synovial tissues demonstrating different patterns of mononuclear cell infiltration.

Synovial membrane samples obtained at knee arthroplasty from 22 patients with rheumatoid arthritis (RA) were characterized histologically. Two groups were identified. Tissue samples from 15 patients demonstrated multiple focal lymphoid aggregates of mononuclear cells (group A). Samples from the remaining seven patients demonstrated diffuse mononuclear cell infiltration (group B). Samples of each synovial membrane (0.25 g) were cultured for cytokine production. The highest levels of IL‐1β and IL‐6 were produced by group A tissues: 19.1 ± 19.6 ng/ml IL‐1β (mean ± s.d.) and 264.4 ± 301.9 ng/ml IL‐6, versus 3.8±6.6 ng/ml and 54.7±42.6 ng/ml respectively. Small quantities of IL‐2 and IL‐4 were measured in both groups: the levels of IL‐2 in group A cultures were highest (P=0.04). Moreover, using MoAbs, the most intense cytokine staining in the tissues was detected in group A. Similar total numbers of each cell subpopulation and similar quantities of immunoglobulin and rheumatoid factor synthesis were measured in both groups. It is suggested that the presence of multiple focal lymphoid aggregates associated with higher levels of cytokine production observed in group A represent a greater degree of immunological activation, and may represent a subgroup of patients with a greater potential for articular destruction.

Acute Myeloid Leukaemia Occurring in Untreated Chronic Lymphatic Leukaemia

Summary. A case of acute myeloid leukaemia (AML) occurring in a patient with untreated chronic lymphatic leukaemia (CLL) is presented. The diagnosis of two simultaneous leukaemic processes is based on morphological, cytochemical and immunological findings. The significance of the development of AML in patients with CLL is discussed.

Flow cytometric measurement of intracellular migration inhibition factor and tumour necrosis factor alpha in the mucosa of patients with coeliac disease

There is increasing evidence that proinflammatory cytokines contribute to many of the small intestinal features in coeliac disease. The aim of the study was to investigate the expression of two proinflammatory cytokines, migration inhibition factor (MIF) and tumour necrosis factor alpha (TNF‐α) in duodenal biopsy specimens from patients with coeliac disease on a gluten‐free diet and normal control subjects. A flow cytometric system was used to analyse intracellular protein levels of MIF and TNF‐α in freshly isolated cells from duodenal biopsies taken from 12 patients with treated coeliac disease and 10 healthy control subjects. From the biopsy specimens, single cell suspensions of the epithelium and lamina propria were prepared using EDTA/DTT and enzymes. Intracellular cytokine expression was studied in intraepithelial lymphocytes (IELs), lamina propria T cells (LP T) and intestinal epithelial cells using different surface labelling antibodies. MIF protein was constitutively expressed in IELs, LP T cells and epithelial cells from normal intestinal mucosa. In contrast, although TNF‐α was found in LP T cells, this cytokine was virtually undetectable in either IELs or epithelial cells. In coeliac disease, intracellular levels of MIF were significantly higher in epithelial cells compared with control subjects (P = 0·005). Raised levels of TNF‐α were found in epithelial cells (P = 0·03) as well as IELs (P = 0·045) from coeliac patients compared with controls. The findings from this study show up‐regulated expression of MIF and TNF‐α in IELs and epithelial cells of histologically normal mucosa in patients with coeliac disease. Increased expression of proinflammatory cytokines in cells occupying the epithelial layer could help explain the rapidity with which the coeliac mucosa may respond to gluten challenge.

Intracellular λ Light Chain Inclusions in Chronic Lymphocytic Leukaemia

A case of chronic lymphocytic leukaemia (CLL) with intracytoplasmic crystalline inclusions in peripheral blood lymphocytes is presented. The inclusions were identified as crystals of lambda (Δ) light chain and were present in bone marrow derived (B‐cells) lymphocytes. The occurrence of light chain crystals in CLL may reflect a more primitive defect in immunoglobulin (Ig) synthesis, intracellular transport or secretion than has previously been reported.

Prevalence of anti-Fab antibodies in patients with autoimmune and infectious diseases.

Sensitive ELISA were devised to examine the specificity of circulating IgM and IgA autoantibodies for whole human IgG, Fe and Fab fragments of human IgG. Sera from patients with autoimmune and infectious conditions such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), tuberculosis (TB), infectious mononucleosis (IM) and cystic fibrosis (CF) were studied. Results of the ELISA assays using whole human IgG as antigen revealed that a proportion of patients in each of the groups studied had circulating IgM and IgA rheumatoid factors (RF). Fifteen normal individuals studied were negative. In the latex positive RA group, IgM RF and IgA RF had primarily anti‐Fc reactivity (100% and 93% respectively), although 3/15 patients also showed IgM anti‐Fab reactivity and one patient had high IgA anti‐Fab activity. Patients with SLE and TB who had detectable RF levels also revealed predominantly anti‐Fc specificity. In contrast, examination of 25 patients with IM showed positivity for IgM RF activity in 8% of patients using whole IgG as antigen, 24% positivity using purified Fc fragments as antigen and 45% positivity when plates were coated with Fab fragments. Similarly, a large number of CF patients (54%) also showed predominantly IgM anti‐Fab activity. Of interest, 69% of the CF patients who were all studied at the time of bacterial infection had detectable IgA RF levels, with 46% of these patients showing both IgA anti‐Fc and anti‐Fab activity. These findings suggest that autoantibody specificities in autoimmune and infectious diseases are different.

Human duodenal epithelial cells constitutively express molecular components of antigen presentation but not costimulatory molecules.

Constitutive expression of major histocompatibility complex (MHC) class II molecules by duodenal epithelial cells (EC) suggests that they can present antigen to CD4(+) T cells. However, other molecular components including invariant chain (Ii), HLA-DM, and costimulatory molecules CD80, CD86 and CD40, are required for efficient T-cell activation. We have investigated whether normal human duodenal EC possess these molecules and whether they can mediate MHC class II antigen presentation. EC were isolated from duodenal biopsies from patients in whom pathology was excluded. Freshly-isolated duodenal EC did not stimulate autologous T-cell proliferation against purified protein derivative of tuberculin. Flow cytometry and immunoblot analysis revealed that duodenal EC constitutively express HLA-DR, Ii, and HLA-DM. Surface MHC class II associated invariant chain peptide (CLIP) was not detectable, suggesting that HLA-DM functions normally in CLIP removal. Duodenal EC expressed SDS-stable HLA-DR alphabeta heterodimers, indicating that peptide binding had occurred. Surface expression of CD80, CD86 or CD40 was not detected although mRNA for these costimulatory molecules was present in all samples. These results suggest that nondiseased human duodenal EC can process and present antigen by the MHC class II pathway, but that they may induce anergy, rather than activation, of local T cells.