Incidence of Henoch-Schönlein purpura, Kawasaki disease, and rare vasculitides in children of different ethnic origins.

BACKGROUND: The frequency and ethnic variation of Henoch-Schönlein purpura, Kawasaki disease, and rarer vasculitides during childhood are not well characterised. Our aim was to ascertain the incidence and ethnic distribution of these conditions in children resident in a region of the UK with a diverse ethnic mix. METHODS: 1.1 million children younger than age 17 years live in the West Midlands. Between Sept 1, 1996, and Aug 31, 1999, we surveyed this population with monthly questionnaires sent to 321 consultants, a single questionnaire sent to 2860 family doctors, and review of 406 case notes with diagnostic codes for vasculitis. We included in the analyses children who fulfilled established criteria for vasculitis with disease onset during the study, and calculated incidence rates from population rates derived from the census of 1991. FINDINGS: We identified 586 new instances of vasculitis and connective tissue disease. The estimated annual incidence of Henoch-Schönlein purpura was 20.4 per 100000, and was highest between the ages of 4 years and 6 years (70.3 per 100000). The estimated annual incidence of Kawasaki disease was 5.5 per 100000 in children younger than 5 years, and was highest in Indian subcontinent Asian children (14.6 per 100000). Indian subcontinent Asian and black children had the highest incidence of systemic lupus erythematosus, juvenile dermatomyositis, and other primary systemic vasculitides. INTERPRETATION: Childhood Henoch-Schönlein purpura is more frequent in the West Midlands than previously reported, and Kawasaki disease has a higher incidence than previously indicated in the UK, with the highest incidence in Indian subcontinental Asian children. Other vasculitis is rare in childhood.

T-cell activation without proliferation in juvenile idiopathic arthritis.

A study was done to determine if the differentiation and activation phenotype of T cells in synovial fluid (SF) from patients with juvenile idiopathic arthritis (JIA) is associated with T-cell proliferation in situ. Mononuclear cells were isolated from 44 paired samples of peripheral blood and SF. Differentiation and activation markers were determined on CD4 and CD8 T cells by flow cytometry. Cell-cycle analysis was performed by propidium iodide staining, and surface-marker expression was also assessed after culture of the T cells under conditions similar to those found in the synovial compartment. The majority of the T cells in the SF were CD45RO+CD45RBdull. There was greater expression of the activation markers CD69, HLA-DR, CD25 and CD71 on T cells from SF than on those from peripheral blood. Actively dividing cells accounted for less than 1% of the total T-cell population in SF. The presence or absence of IL-16 in T-cell cultures with SF or in a hypoxic environment did not affect the expression of markers of T-cell activation. T cells from the SF of patients with JIA were highly differentiated and expressed early and late markers of activation with little evidence of in situ proliferation. This observation refines and extends previous reports of the SF T-cell phenotype in JIA and may have important implications for our understanding of chronic inflammation.

An association between the acute phase response and patterns of antigen induced T cell proliferation in juvenile idiopathic arthritis.

The aim of this research was to determine whether all memory T cells have the same propensity to migrate to the joint in patients with juvenile idiopathic arthritis. Paired synovial fluid and peripheral blood mononuclear cell proliferative responses to a panel of antigens were measured and the results correlated with a detailed set of laboratory and clinical data from 39 patients with juvenile idiopathic arthritis. Two distinct patterns of proliferative response were found in the majority of patients: a diverse pattern, in which synovial fluid responses were greater than peripheral blood responses for all antigens tested; and a restricted pattern, in which peripheral blood responses to some antigens were more vigorous than those in the synovial fluid compartment. The diverse pattern was generally found in patients with a high acute phase response, whereas patients without elevated acute phase proteins were more likely to demonstrate a restricted pattern. We propose that an association between the synovial fluid T cell repertoire and the acute phase response suggests that proinflammatory cytokines may influence recruitment of memory T cells to an inflammatory site, independent of their antigen specificity. Additionally, increased responses to enteric bacteria and the presence of alphaEbeta7 T cells in synovial fluid may reflect accumulation of gut associated T cells in the synovial compartment, even in the absence of an elevated acute phase response. This is the first report of an association between the acute phase response and the T cell population recruited to an inflammatory site.