Pathogenesis of scleroderma: the interrelationship of the immune and vascular hypotheses

Increase in activated T cells and reduction in suppressor inducer T cells in systemic sclerosis

Blood lymphocytes from 37 patients with systemic sclerosis were characterised using monoclonal antibodies in a two colour flow cytometric (fluorescence activated cell sorter (FACS)) analysis. The ratio of helper CD4+ to suppressor/cytotoxic CD8+ T cells was raised in patients compared with that in 30 healthy controls owing to decreased CD8+ cells. In the patients CD4+ and CD8+ cells displayed an increased expression of the activation marker HLA-DR. The relative number of CD11b+ CD8+ lymphocytes (suppressor T cells) was normal, but the calculated absolute counts of this cell type were slightly reduced. The proportions and absolute numbers of suppressor inducer T cells, defined as CD45R+ CD4+ cells, were on average only half the levels observed in controls. These findings were not related to the inflammatory activity as measured by acute phase plasma proteins or serum immunoglobulins. Activated T cells were seen at all stages of the sclerotic process and especially during the early stages of the disease and in patients who had suffered occupational exposure to silica dust. A high proportion of activated T cells was also linked with impaired small intestine function but not with the degree of skin or lung involvement. A loss of suppressor inducer T cells was more pronounced later in the disease and in patients with the CREST (calcinosis, Raynaud's phenomenon, oesophageal dysmotility, sclerodactyly, telangiectasia) syndrome. These data provide further evidence for an involvement of T cell mediated immunity in the perpetuation of systemic sclerosis.

Polymorphonuclear neutrophil function in systemic sclerosis

In vitro functions of polymorphonuclear (PMN) neutrophils were studied in 20 patients with progressive systemic sclerosis (PSS). An increase in the basal chemiluminescence (CL) activity of peripheral blood PMNs was found, suggesting that these cells had been preactivated in vivo. Patients with more extensive skin disease or signs of disease progression tended to have higher basal CL values. Active oxygen products during the respiratory burst may increase the extent of inflammatory and fibrotic processes and could be involved in the endothelial injury in PSS. The stimulatory capacity of CL response was normal in our study. No alterations were found in the opsonised yeast phagocytic activity of granulocytes when compared with control values. The binding of erythrocyte-antibody particles was found also to be normal. A depressed chemotactic activity of PMN cells against zymosan activated serum was also shown. The cause of the decreased chemotaxis of PMNs remains to be elucidated.